Fixed-rate mortgage: Difference between revisions

From formulasearchengine
Jump to navigation Jump to search
en>Zorrobot
 
en>Patrick
Line 1: Line 1:
Jerrie is what you in many cases can call me but I don't like when visitors use my full identify. The job I've been occupying for years is an actual people manager. Guam is even I've always been residing. What I genuinely like doing is [http://Www.Wired.com/search?query=fish+preventing fish preventing] and I'll be initiating something else along going without running shoes. Go to the group website to find from more: http://[http://www.Squidoo.com/search/results?q=circuspartypanama circuspartypanama].com<br><br>My website ... [http://circuspartypanama.com clash of clans cheat]
A striking feature of [[projective plane]]s is the "[[symmetry]]" of the roles played by points and lines in the definitions and theorems, and (plane) '''duality''' is the formalization of this [[Metamathematics|metamathematical]] concept. There are two approaches to the subject of duality, one through language (the [[#Principle of Duality|Principle of Duality]]) and the other a more functional approach. These are completely equivalent and either treatment has as its starting point the [[axiomatic]] version of the geometries under consideration. In the functional approach there is a map between related geometries which is called a '''''duality'''''. In specific examples, such a map can be constructed in many ways. The concept of plane duality readily extends to space duality and beyond that to duality in any finite dimensional projective geometry.
 
==Principle of Duality==
 
{{details|Incidence structure#Dual structure}}
If one defines a [[projective plane]] axiomatically as an [[incidence structure]], in terms of a set ''P'' of points, a set ''L'' of lines, and an [[incidence relation]] ''I'' that determines which points lie on which lines, then one may define a '''plane dual structure'''.
 
Interchange the role of "points" and "lines" in 
:C=(P,L,I)
to obtain the dual structure
:C* =(L,P,I*),
where ''I*'' is the [[inverse relation]] of ''I''. C* is also a projective plane, called the '''dual plane''' of C.
 
If C and C* are isomorphic, then C is called '''''self-dual'''''. The projective planes PG(2,''K'') for any field (or, more generally, for every division ring isomorphic to its dual) ''K'' are self-dual. In particular, Desargusian planes of finite order are always self-dual. However, there are [[non-Desarguesian plane]]s which are not self-dual, such as the Hall planes and some that are, such as the [[Hughes plane]]s.
 
In a projective plane a statement involving points, lines and incidence between them that is obtained from another such statement by interchanging the words "point" and "line" and making whatever grammatical adjustments that are necessary, is called the '''plane dual statement''' of the first. The plane dual statement of "Two points are on a unique line." is "Two lines meet at a unique point." Forming the plane dual of a statement is known as ''dualizing'' the statement.
 
If a statement is true in a projective plane C, then the plane dual of that statement must be true in the dual plane C*. This follows since dualizing each statement in the proof "in C" gives a statement of the proof "in C*."
 
The '''''Principle of Plane Duality''''' says that dualizing any theorem in a self-dual projective plane C produces another theorem valid in C.
 
The above concepts can be generalized to talk about space duality, where the terms "points" and "planes" are interchanged (and lines remain lines). This leads to the ''Principle of Space Duality''. Further generalization is possible (see below).
 
These principles provide a good reason for preferring to use a "symmetric" term for the incidence relation. Thus instead of saying "a point lies on a line" one should say "a point is incident with a line" since dualizing the latter only involves interchanging point and line ("a line is incident with a point").
 
Traditionally in projective geometry, the set of points on a line are considered to include the relation of [[projective harmonic conjugate]]s. In this tradition the points on a line form a [[projective range]], a concept dual to a [[pencil (mathematics)|pencil of lines]] on a point.
 
===Dual Theorems===
As the real projective plane, PG(2,'''R'''), is self-dual there are a number of pairs of well known results that are duals of each other. Some of these are:
 
*  [[Desargues' theorem]] ⇔ [[Desargues' theorem|Converse of Desargues' theorem]]
*  [[Pascal's theorem]] ⇔ [[Brianchon's theorem]]
*  [[Menelaus' theorem]]  ⇔ [[Ceva's theorem]]
 
==Duality as a mapping==
 
A (plane) '''duality''' is a map from a projective plane C = (P,L,I) to its dual plane C* = (L,P,I*) (see [[#Principle of Duality|above]]) which preserves incidence. That is, a (plane) duality σ will map points to lines and lines to points (P<sup>σ</sup> = L and L<sup>σ</sup> = P) in such a way that if a point Q is on a line m ( denoted by Q I m) then Q<sup>σ</sup> I* m<sup>σ</sup> ⇔ m<sup>σ</sup> I Q<sup>σ</sup>. A (plane) duality which is an isomorphism is called a '''correlation'''.<ref>{{harvnb|Dembowski|1968}}  pg.151.</ref> The existence of a correlation means that the projective plane C is self-dual.
 
In the special case that the projective plane is of the [[Projective space|PG(2,''K'')]] type, with ''K'' a division ring, a duality is called a '''reciprocity'''.<ref>{{harvnb|Casse|2006|loc=p. 94}}</ref>  By the [[Fundamental theorem of projective geometry]] a reciprocity is the composition of an [[automorphic function]] of ''K'' and a [[homography]]. If the automorphism involved is the identity, then the reciprocity is called a '''projective correlation'''.
 
A correlation of order two (an [[Involution (mathematics)|involution]]) is called a '''polarity'''. If a correlation φ is not a polarity then φ<sup>2</sup> is a nontrivial collineation.
 
This duality mapping concept can also be extended to higher dimensional spaces so the modifier "(plane)" can be dropped in those situations.
 
==Higher dimensional duality==
 
Duality in the projective plane is a special case of duality for [[projective space]]s, transformations of PG(n,''K'') (also denoted by ''K'''''P'''<sup>n</sup>) with ''K'' a field,  that interchange objects of dimension ''r'' with objects of dimension ''n - 1 - r'' ( = [[codimension]] r + 1). That is, in a projective space of dimension ''n'', the points (dimension 0) are made to correspond with [[hyperplane]]s (codimension 1), the lines joining two points (dimension 1) are made to correspond with the intersection of two hyperplanes (codimension 2), and so on.
 
The points of PG(n,''K'') can be taken to be the nonzero vectors in the (''n''&nbsp;+&nbsp;1)-dimensional vector space over ''K'', where we identify two vectors which differ by a scalar factor. Another way to put it is that the points of ''n''-dimensional projective space are the lines through the origin in ''K''<sup>''n''&nbsp;+&nbsp;1</sup>, which are 1-dimensional vector [[Linear subspace|subspaces]].<ref>Dimension is being used here in two different senses. When referring to a projective space, the term is used in the common geometric way where lines are 1-dimensional and planes are 2-dimensional objects. However, when applied to a vector space, dimension means the number of vectors in a basis, and a basis for a vector subspace thought of as a line has two vectors in it, while a basis for a vector space thought of as a plane has three vectors in it. If the meaning is not clear from the context, the terms ''projective'' or ''geometric'' are applied to the projective space concept while ''algebraic'' or ''vector'' are applied to the vector space one. The relation between the two is simply: algebraic dimension = geometric dimension + 1.</ref> Also the ''n''- vector dimensional subspaces of ''K''<sup>''n''&nbsp;+&nbsp;1</sup> represent the (''n''&nbsp;&minus;&nbsp;1)- geometric dimensional hyperplanes of projective ''n''-space over ''K''.
 
A nonzero vector '''u''' = (''u<sub>0</sub>,u<sub>1</sub>,...,u<sub>n</sub>'')  in ''K''<sup>''n''&nbsp;+&nbsp;1</sup> also determines an (n - 1) - geometric dimensional subspace (hyperplane) H<sub>'''u'''</sub>, by
:H<sub>'''u'''</sub> = {(''x<sub>0</sub>,x<sub>1</sub>,...,x<sub>n</sub>'') : ''u<sub>0</sub>x<sub>0</sub>'' + … + ''u<sub>n</sub>x<sub>n</sub>'' = 0 }.
When a vector '''u''' is used to define a hyperplane in this way it shall be denoted by '''u'''<sub>H</sub>, while if it is designating a point we will use '''u'''<sub>P</sub>. In terms of the usual [[dot product]], H<sub>'''u'''</sub> = {'''x'''<sub>P</sub> : '''u'''<sub>H</sub> • '''x'''<sub>P</sub> = 0}. Since ''K'' is a field, the dot product is symmetrical, meaning '''u'''<sub>H</sub>•'''x'''<sub>P</sub> = ''u<sub>0</sub>x<sub>0</sub>'' + ''u<sub>1</sub>x<sub>1</sub>'' + ... + ''u<sub>n</sub>x<sub>n</sub>'' = ''x<sub>0</sub>u<sub>0</sub>'' + ''x<sub>1</sub>u<sub>1</sub>'' + ... + ''x<sub>n</sub>u<sub>n</sub>'' = '''x'''<sub>H</sub>•'''u'''<sub>P</sub>. A reciprocity can be given by '''u'''<sub>P</sub> ↔ H<sub>'''u'''</sub> between points and hyperplanes. This extends to a reciprocity between the line generated by two points and the intersection of two such hyperplanes, and so forth.
 
In the projective plane, PG(2,''K''), with ''K'' a field we have the reciprocity given by: points in [[homogeneous coordinates]] (''a,b,c'') ↔ lines with equations ''ax'' + ''by'' + ''cz'' = ''0''. In a corresponding projective space, PG(3,''K''), a reciprocity is given by: points in homogeneous coordinates (''a,b,c,d'') ↔ planes with equations ''ax'' + ''by'' + ''cz'' + ''dw'' = 0. This reciprocity would also map a line determined by two points (''a<sub>1</sub>,b<sub>1</sub>,c<sub>1</sub>,d<sub>1</sub>'') and (''a<sub>2</sub>,b<sub>2</sub>,c<sub>2</sub>,d<sub>2</sub>'') to the line which is the intersection of the two planes with equations ''a<sub>1</sub>x'' + ''b<sub>1</sub>y'' + ''c<sub>1</sub>z'' + ''d<sub>1</sub>w'' = 0 and ''a<sub>2</sub>x'' + ''b<sub>2</sub>y'' + ''c<sub>2</sub>z'' + ''d<sub>2</sub>w'' = 0.
 
==Three dimensions==
 
In a polarity of real projective 3-space, PG(3,'''R'''), points correspond to planes, and lines correspond to lines. By restriction the [[dual polyhedron|duality of polyhedra]] in [[solid geometry]] is obtained, where points are dual to faces, and sides are dual to sides, so that the [[icosahedron]] is dual to the [[dodecahedron]], and the [[cube]] is dual to the [[octahedron]].
 
==Geometric construction of a reciprocity==
 
The reciprocity of PG(2,R),  given by homogeneous coordinates can also be described geometrically. This uses the [[mathematical model|model]] of the [[real projective plane]]  which is a "unit sphere with antipodes<ref>the points of a sphere at opposite ends of a diameter are called ''antipodal points''.</ref> identified", or equivalently, the model of lines and planes through the origin of the vector space R<sup>3</sup>. Associate a line through the origin with the unique plane through the origin which is perpendicular (orthogonal) to the line. When, in the model, these lines are considered to be the points and the planes the lines of the projective plane PG(2,R), this association becomes a reciprocity (actually a polarity) of the projective plane. The sphere model is obtained by intersecting the lines and planes through the origin with a unit sphere centered at the origin. The lines meet the sphere in antipodal points which must then be identified to obtain a point of the projective plane, and the planes meet the sphere in [[great circle]]s which are thus the lines of the projective plane.
 
That this association "preserves" incidence is most easily seen from the lines and planes model. A point incident with a line in the projective plane corresponds to a line lying in a plane in the model. Applying the association, the plane becomes a line through the origin perpendicular to the plane it is associated with. This image line is perpendicular to every line of the plane which passes through the origin, in particular the original line (point of the projective plane). All lines that are perpendicular to the original line at the origin lie in the unique plane which is orthogonal to the original line, that is, the image plane under the association. Thus, the image line lies in the image plane and the association preserves incidence.
 
==Poles and polars==
{{Main|Pole and polar}}
[[File:Pole and polar.svg|thumb|right|Pole and polar with respect to circle ''O''. ''P'' = ''Q''', ''q'' is polar of ''Q'', ''Q'' is pole of ''q''.]]
In the Euclidean plane, fix a circle ''C'' with center ''O'' and radius ''r''. For each point ''P'' other than ''O'' define an image point ''P''' so that ''OP'' • ''OP''' = ''r<sup>2</sup>''. The mapping defined by ''P'' → ''P''' is called '''[[Inversive geometry|inversion]]''' with respect to circle ''C''. The line through ''P''' which is perpendicular to the line ''OP'' is called the '''polar''' of the point ''P'' with respect to circle ''C''. Let ''m'' be a line not passing through ''O''. Drop a perpendicular from ''O'' to ''m'', meeting ''m'' at the point ''Q'' (this is the point of ''m'' that is closest to ''O''). The image of ''Q'' under inversion with respect to ''C'' is called the '''pole''' of ''m''. If a point ''P'' (different from ''O'') is on a line ''m'' (not passing through ''O'') then the pole of ''m'' lies on the polar of ''P'' and viceversa. The incidence preserving process, in which points and lines are transformed into their polars and poles with respect to ''C'' is called '''reciprocation'''.<ref>{{harvnb|Coxeter and Greitzer|1967}} pg.133</ref> In order to turn this process into a reciprocity, the Euclidean plane (which is not a projective plane) needs to be expanded to the [[Projective plane|extended euclidean plane]] by adding a [[line at infinity]] and [[points at infinity]] which lie on this line. In this expanded plane, we define the polar of the point ''O'' to be the line at infinity (and ''O'' is the pole of the line at infinity), and the poles of the lines through ''O'' are the points of infinity where, if a line has [[slope]] ''s'' (≠ 0) its pole is the infinite point associated to the parallel class of lines with slope ''-1/s''. The pole of the x-axis is the point of infinity of the vertical lines and the pole of the y-axis is the point of infinity of the horizontal lines.
 
The construction of a reciprocity based on inversion in a circle given above can be generalized by using inversion in a conic section (in the extended real plane). The reciprocities constructed in this manner are projective correlations of order two, that is, polarities.
 
==Mapping the sphere onto the plane==
The unit sphere modulo &minus;1 model of the projective plane is [[isomorphism|isomorphic]] (w.r.t. incidence properties) to the planar model: the affine plane extended with a projective line at infinity.
 
To map a point on the sphere to a point on the plane, let the plane be tangent to the sphere at some point which shall be the origin of the plane's coordinate system (2-D origin).  Then construct a line passing through the center of the sphere (3-D origin) and the point on the sphere.  This line intersects the plane at a point which is the projection of the point on the sphere onto the plane (or vice versa).
 
This projection can be used to define a one-to-one onto mapping
:<math> f:[0,\pi/2] \times [0,2 \pi] \rightarrow \mathbb{R}P^2. </math>
If points in <math> \mathbb{R}P^2 </math> are expressed in [[homogeneous coordinates]], then
:<math> f:(\theta, \phi) \mapsto [\cos \phi : \sin \phi : \cot \theta], </math>
:<math> f^{-1} : [x : y : z] \mapsto \left( \arctan \sqrt{\left({x \over z}\right)^2 + \left({y\over z}\right)^2}, \arctan_2 (y,x) \right). </math>
 
Also, lines in the planar model are projections of great circles of the sphere.  This is so because through any line in the plane pass an infinitude of different planes: one of these planes passes through the 3-D origin, but a plane passing through the 3-D origin intersects the sphere along a great circle.
 
As we have seen, any great circle in the unit sphere has a projective point perpendicular to it, which can be defined as its dual.  But this point is a pair of antipodal points on the unit sphere, through both of which passes a unique 3-D line, and this line extended past the unit sphere intersects the tangent plane at a point, which means that there is a geometric way to associate a unique point on the plane to every line on the plane, such that the point is the dual of the line.
 
==Duality mapping defined==
Given a line ''L'' in the projective plane, what is its dual point?  Draw a line  ''L&prime;'' passing through the 2-D origin and perpendicular to line ''L''.  Then pick a point ''P'' on line ''L&prime;'' on the other side of the origin from line ''L'', such that the distance of point ''P'' to the origin is the [[Multiplicative inverse|reciprocal]] of the distance of line ''L'' to the origin.
 
<!-- {|
|
:: [[File:ProjectiveDuality.PNG]]
|-
|
::''<small>Figure 1.  Three pairs of dual points and lines: one red pair, one yellow pair, <br>and one blue pair. The duality is an isomorphism of incidence, so that, e.g., <br>the line passing through the red and yellow points is dual to the intersection<br> of the red and yellow lines. </small>''
|} -->
:: [[File:ProjectiveDuality.PNG]]
::''<small>Figure 1.  Three pairs of dual points and lines: one red pair, one yellow pair, <br>and one blue pair.  The duality is an isomorphism of incidence, so that, e.g., <br>the line passing through the red and yellow points is dual to the intersection<br> of the red and yellow lines. </small>''
 
Expressed algebraically, let ''g'' be a one-to-one mapping from the projective plane onto itself:
:<math> g : \mathbb{R}P^2 \rightarrow \mathbb{R}P^2 </math>
such that
:<math> g : [m : b : 1]_L \mapsto [m : -1 : b] </math>
and
:<math> g : [x : y : 1] \mapsto [x : 1 : -y]_L </math>
where the L subscript is used to semantically distinguish [[line coordinates]] from point coordinates.  In words, affine line (''m'', ''b'') with slope ''m'' and y-intercept ''b'' is the dual of point (''m''/''b'', &minus;1/''b'').  If ''b''=0 then the line passes through the 2-D origin and its dual is the ideal point [m : &minus;1 : 0]. 
 
The affine point with Cartesian coordinates (''x'',''y'') has as its dual the line whose slope is &minus;''x''/''y'' and whose y-intercept is &minus;1/''y''.  If the point is the 2-D origin [0:0:1], then its dual is [0:1:0]<sub>L</sub> which is the line at infinity.  If the point is [''x'':0:1], on the x-axis, then its dual is line [''x'':1:0]<sub>L</sub> which shall be interpreted as a line whose slope is vertical and whose x-intercept is &minus;1/''x''.
 
If a point or a line's homogeneous coordinates are represented as a vector in 3x1 [[matrix (mathematics)|matrix]] form, then the duality mapping ''g'' can be represented by a 3x3 matrix
:<math> G = \begin{bmatrix} 1 & 0 & 0 \\ 0 & 0 & -1 \\ 0 & 1 & 0 \end{bmatrix} </math>
whose inverse is
:<math> G^{-1} = \begin{bmatrix} 1 & 0 & 0 \\ 0 & 0 & 1 \\ 0 & -1 & 0 \end{bmatrix}. </math>
Matrix ''G'' has one real eigenvalue: one, whose [[eigenvector]] is [1:0:0].  The line [1:0:0]<sub>L</sub> is the y-axis, whose dual is the ideal point [1:0:0] which is the intersection of the ideal line with the x-axis.
 
Notice that [1:0:0]<sub>L</sub> is the y-axis, [0:1:0]<sub>L</sub> is the line at infinity, and [0:0:1]<sub>L</sub> is the x-axis.  In 3-space, matrix ''G'' is a 90° rotation about the x-axis which turns the y-axis into the z-axis.  In projective 2-space, matrix ''G'' is a projective transformation which maps points to points, lines to lines, conic sections to conic sections: it exchanges the line at infinity with the x-axis and maps the y-axis onto itself through a Möbius transformation.  As a duality, matrix ''G'' pairs up each projective line with its dual projective point.
 
==Preservation of incidence==
The duality mapping ''g'' is an isomorphism with respect to the incidence properties (such as collinearity and concurrency).  The mapping ''g'' has this property: given a pair of lines ''L<sub>1</sub>'' and ''L<sub>2</sub>'' which intersect at a point ''P'', then their dual points ''gL<sub>1</sub>'' and ''gL<sub>2</sub>'' define the unique line ''g<sup>&minus;1</sub>P'':
:<math> g^{-1} (L_1 \cap L_2) = gL_1 . gL_2 </math>.
 
Given points ''P<sub>1</sub>'' and ''P<sub>2</sub>'' through which passes line ''L'', ''P<sub>1</sub>.P<sub>2</sub> = L'', then what is the intersection of lines ''g<sup>&minus;1</sub>P<sub>1</sub>'' and ''g<sup>&minus;1</sub>P<sub>2</sub>''? If ''g<sup>&minus;1</sup>P<sub>1</sub>'' ∩ ''g<sup>&minus;1</sup>P<sub>2</sub>'' = ''P'' then
:<math> g^{-1}P = g^{-1}(g^{-1}P_1 \cap g^{-1}P_2) = g(g^{-1}P_1).g(g^{-1}P_2)</math>
:::<math> = P_1.P_2 </math>
:::<math> = L </math>
so that
:<math> g(g^{-1}P) = gL </math>
:<math> P = gL </math>
:∴<math>g(P_1.P_2) = g^{-1}P_1 \cap g^{-1}P_2</math>
 
Given a pair of affine points in homogeneous coordinates, the line passing through them is
:<math> [x_1:y_1:1].[x_2:y_2:1] = g^{-1} ([x_1:y_1:1] \times [x_2:y_2:1]) </math>
where the [[cross product]] is computed just as it would for an ordinary pair vectors in 3-space.
 
From this last equation can be derived the intersection of lines, by using the mapping ''g'' to "plug in" the lines into the slots for points:
:<math>g[m_1:b_1:1]_L . g[m_2:b_2:1]_L = g^{-1}(g[m_1:b_1:1]_L \times g[m_2:b_2:1]_L) </math>
 
:<math>g(g[m_1:b_1:1]_L . g[m_2:b_2:1]_L) = g[m_1:b_1:1]_L \times g[m_2:b_2:1]_L </math>
 
:<math>[m_1:b_1:1]_L \cap [m_2:b_2:1]_L = g([m_1:b_1:1]_L \times [m_2:b_2:1]_L)</math>
where mapping ''g'' is seen to distribute with respect to the cross product: i.e. ''g'' is an isomorphism of cross product.
 
''Theorem.'' The duality mapping ''g'' is an isomorphism of cross product.  I.e. ''g'' is distributive w.r.t. cross product.
 
''Proof.'' Given points ''A''=(''a'':''b'':''c'') and ''B''=(''d'':''e'':''f''), their cross product is
<math> (a:b:c) \times (d:e:f) = (b f - c e : c d - a f : a e - b d) </math>
but
:<math> g(a:b:c) = (a:-c:b),</math>
 
:<math> g(d:e:f) = (d:-f:e), </math>
 
:<math> (a:-c:b) \times (d:-f:e) = (-c e + b f : b d - a e : -a f + c d) </math>
 
::::<math>= g(b f - c e : c d - a f : a e - b d)</math>.
Therefore
:<math> g(A \times B) = gA \times gB </math>.
''[[Q.E.D.]]''
 
==Notes==
{{reflist}}
 
==See also==
* [[Dual curve]]
 
==References==
*{{Citation | last1 = Albert | first1 = A. Adrian | last2 = Sandler | first2 = Reuben | title = An Introduction to Finite Projective Planes | publisher = Holt, Rinehart and Winston | place = New York | year = 1968}}
* <cite id=refBachmann1959>F. Bachmann, 1959. ''Aufbau der Geometrie aus dem Spiegelungsbegriff'', Springer, Berlin.</cite>
* {{cite book|last=Baer|first=Reinhold|title=Linear Algebra and Projective Geometry|year=2005|publisher=Dover|location=Mineola NY|isbn=0-486-44565-8}}
* {{cite book|last=Bennett|first=M.K.|title=Affine and Projective Geometry|year=1995|publisher=Wiley|location=New York|isbn=0-471-11315-8}}
* {{cite book|last1=Beutelspacher|first1=Albrecht|last2=Rosenbaum|first2=Ute|title=Projective Geometry: from foundations to applications|year=1998|publisher=Cambridge University Press|location=Cambridge|isbn=0-521-48277-1}}
* {{citation|last=Casse|first=Rey|title=Projective Geometry: An Introduction|year=2006|publisher=Oxford University Press|location=New York|isbn=0-19-929886-6}}
* <cite id=refCederberg2001>{{cite book
| last=Cederberg
| first=Judith N.
| title=A Course in Modern Geometries
| location=New York
| publisher=Springer-Verlag
| year=2001
| isbn=0-387-98972-2}}</cite>
* [[H. S. M. Coxeter|Coxeter, H. S. M.]], 1995. ''The Real Projective Plane'', 3rd ed. Springer Verlag.
* <cite id=refCoxeter2003>Coxeter, H. S. M., 2003. ''Projective Geometry'', 2nd ed. Springer Verlag. ISBN 978-0-387-40623-7.</cite>
* <cite id=refCoxeter1969>{{cite book
| last=Coxeter
| first=H. S. M.
| title=Introduction to Geometry
| location=New York
| publisher=John Wiley & Sons
| year=1969
| isbn=0-471-50458-0}}</cite>
* {{citation|last=Coxeter|first=H.S.M.|last2=Greitzer|first2=S.L.|title=Geometry Revisited|year=1967|publisher=Mathematical Association of America|location=Washington, D.C.|isbn=0-88385-600-X}}
*{{Citation | last = Dembowski | first = Peter | title = Finite Geometries | publisher = Springer Verlag | place = Berlin | year = 1968}}
* {{cite book|last=Garner|first=Lynn E.|title=An Outline of Projective Geometry|year=1981|publisher=North Holland|location=New York|isbn=0-444-00423-8}}
* Greenberg, M.J., 2007. ''Euclidean and non-Euclidean geometries'', 4th ed. Freeman.
* [[Robin Hartshorne|Hartshorne, Robin]], 2009. ''Foundations of Projective Geometry'', 2nd ed. Ishi Press. ISBN 978-4-87187-837-1
* Hartshorne, Robin, 2000. ''Geometry: Euclid and Beyond''. Springer.
* [[David Hilbert|Hilbert, D.]] and Cohn-Vossen, S., 1999. ''Geometry and the imagination'', 2nd ed. Chelsea.
* <cite id=refHughes1973>D. R. Hughes and F. C. Piper, 1973. ''Projective Planes'', Springer.</cite>
*{{Citation | last = Kárteszi | first = F. | title = Introduction to Finite Geometries| publisher = North-Holland | place = Amsterdam | year = 1976 | isbn = 0-7204-2832-7}}
* {{cite book|last=Mihalek|first=R.J.|title=Projective Geometry and Algebraic Structures|year=1972|publisher=Academic Press|location=New York|isbn=0-12-495550-9}}
* <cite id=refRamanan1997>{{cite journal
| doi=10.1007/BF02835009
| first=S.
| last=Ramanan
| title=Projective geometry
| journal=Resonance
|publisher=Springer India
|issn=0971-8044
|volume =2
|issue=8
|pages=87–94
|date=August 1997 }}
*{{cite book|last=Samuel|first=Pierre|title=Projective Geometry|year=1988|publisher=Springer-Verlag|location=New York|isbn=0-387-96752-4}}
*{{Citation | last = Stevenson | first = Frederick W. | title = Projective Planes | publisher = W.H. Freeman and Company | place = San Francisco |year = 1972 | isbn = 0-7167-0443-9}}
*{{Cite book|first=Oswald|last=Veblen|first2=J. W. A.|last2= Young|title=Projective geometry|year=1938|place=Boston|publisher= Ginn & Co.|url=http://www.archive.org/details/117714799_001|isbn=978-1-4181-8285-4|postscript=<!--None-->}}
 
==External links==
{{MathWorld|title=Duality Principle|urlname=DualityPrinciple}}
 
[[Category:Projective geometry]]
[[Category:Duality theories|Projective geometry]]

Revision as of 15:52, 29 November 2013

A striking feature of projective planes is the "symmetry" of the roles played by points and lines in the definitions and theorems, and (plane) duality is the formalization of this metamathematical concept. There are two approaches to the subject of duality, one through language (the Principle of Duality) and the other a more functional approach. These are completely equivalent and either treatment has as its starting point the axiomatic version of the geometries under consideration. In the functional approach there is a map between related geometries which is called a duality. In specific examples, such a map can be constructed in many ways. The concept of plane duality readily extends to space duality and beyond that to duality in any finite dimensional projective geometry.

Principle of Duality

DTZ gives a comprehensive integrated property and services administration resolution for buyers, corporate house for sale In singapore owners, management firms and occupiers of property whatever their needs with the only goal of optimising and enhancing the investment worth of their property. We at the moment make use of a staff of more than 70 skilled staffs who are well-trained and dedicated to collectively achieving our purchasers' objectives.

Actual estate agency specialising in non-public condos and landed properties island vast. 10 Winstedt Highway, District 10, #01-thirteen, Singapore 227977. Property providers for enterprise relocation. Situated at 371 Beach Street, #19-10 KeyPoint, Singapore 199597. Property agents for homes, town houses, landed property, residences and condominium for sales and rentals of properties. Administration letting services for property homeowners. is there a single authority in singapore who regulates real property agents that i can file a complaint with for unethical behaviour? or is CASE is simply route? The 188 pages of Secrets and techniques of Singapore Property Gurus are full of professional knowledge and life altering wisdom. Asian industrial property market outlook Property Listing Supervisor Property Advertising Services

Should sellers go along with an agent who claims to specialize in your space? His experience might turn out to be useful, but he is probably additionally advertising a number of models within the neighbourhood – and so they're all your rivals. Within the worst-case state of affairs, your house may be used as a "showflat" as house owner YS Liang found. "Weekend after weekend, our agent would convey a stream of individuals to speed-go to our apartment, leaving within minutes. She did not even try to promote our condominium. It felt like we were just one of the many tour stops for her clients," he complains.

Step one in direction of conducting enterprise as an actual property company in Singapore is to include an organization, or if you happen to're going the partnership or sole-proprietorship route, register your Limited Legal responsibility Partnership or sole-proprietorship with the ACRA (Accounting and Company Regulatory Authority of Singapore) Whether or not you might be considering to promote, let, hire or buy a new industrial property, we're right here to assist. Search and browse our commercial property section. Possess not less than 3 years of working expertise below a Singapore licensed real-property agency; Sale, letting and property administration and taxation companies. three Shenton Means, #10-08 Shenton Home, Singapore 068805. Real property agents for purchasing, promoting, leasing, and renting property. Caveat Search

Firstly, the events might take into account to rescind the sale and buy agreement altogether. This avenue places the contracting events to a position as if the contract didn't happen. It's as if the contract was terminated from the start and events are put back into place that they were before the contract. Any items or monies handed are returned to the respective original house owners. As the worldwide real property market turns into extra refined and worldwide real property investments will increase, the ERA real estate network is well equipped to offer professional recommendation and guidance to our shoppers in making critical actual estate decisions. Relocationg, leasing and sales of properties for housing, food and beverage, retail and workplace wants.

Pasir Panjang, Singapore - $5,000-6,000 per 30 days By likelihood one among our buddies here in Singapore is an agent and we made contact for her to help us locate an residence, which she did. days from the date of execution if the doc is signed in Singapore; Be a Singapore Citizen or PR (Permanent Resident); The regulations also prohibit property agents from referring their shoppers to moneylenders, to discourage irresponsible shopping for. Brokers are additionally prohibited from holding or dealing with money on behalf of any party in relation to the sale or purchase of any property situated in Singapore, and the lease of HDB property. - Negotiate To Close A Sale together with sale and lease of HDB and private properties) Preparing your house for sale FEATURED COMMERCIAL AGENTS Property Guides

i) registered as a patent agent or its equal in any nation or territory, or by a patent workplace, specified within the Fourth Schedule; The business-specific tips for the true property agency and telecommunication sectors have been crafted to address considerations about scenarios that particularly apply to the two sectors, the PDPC stated. Mr Steven Tan, Managing Director of OrangeTee real property company, nonetheless, felt that it was a matter of "practising until it becomes part of our knowledge". "After a while, the agents ought to know the spirit behind the (Act)," he stated. Rising office sector leads real property market efficiency, while prime retail and enterprise park segments moderate and residential sector continues in decline Please choose an attendee for donation. If one defines a projective plane axiomatically as an incidence structure, in terms of a set P of points, a set L of lines, and an incidence relation I that determines which points lie on which lines, then one may define a plane dual structure.

Interchange the role of "points" and "lines" in

C=(P,L,I)

to obtain the dual structure

C* =(L,P,I*),

where I* is the inverse relation of I. C* is also a projective plane, called the dual plane of C.

If C and C* are isomorphic, then C is called self-dual. The projective planes PG(2,K) for any field (or, more generally, for every division ring isomorphic to its dual) K are self-dual. In particular, Desargusian planes of finite order are always self-dual. However, there are non-Desarguesian planes which are not self-dual, such as the Hall planes and some that are, such as the Hughes planes.

In a projective plane a statement involving points, lines and incidence between them that is obtained from another such statement by interchanging the words "point" and "line" and making whatever grammatical adjustments that are necessary, is called the plane dual statement of the first. The plane dual statement of "Two points are on a unique line." is "Two lines meet at a unique point." Forming the plane dual of a statement is known as dualizing the statement.

If a statement is true in a projective plane C, then the plane dual of that statement must be true in the dual plane C*. This follows since dualizing each statement in the proof "in C" gives a statement of the proof "in C*."

The Principle of Plane Duality says that dualizing any theorem in a self-dual projective plane C produces another theorem valid in C.

The above concepts can be generalized to talk about space duality, where the terms "points" and "planes" are interchanged (and lines remain lines). This leads to the Principle of Space Duality. Further generalization is possible (see below).

These principles provide a good reason for preferring to use a "symmetric" term for the incidence relation. Thus instead of saying "a point lies on a line" one should say "a point is incident with a line" since dualizing the latter only involves interchanging point and line ("a line is incident with a point").

Traditionally in projective geometry, the set of points on a line are considered to include the relation of projective harmonic conjugates. In this tradition the points on a line form a projective range, a concept dual to a pencil of lines on a point.

Dual Theorems

As the real projective plane, PG(2,R), is self-dual there are a number of pairs of well known results that are duals of each other. Some of these are:

Duality as a mapping

A (plane) duality is a map from a projective plane C = (P,L,I) to its dual plane C* = (L,P,I*) (see above) which preserves incidence. That is, a (plane) duality σ will map points to lines and lines to points (Pσ = L and Lσ = P) in such a way that if a point Q is on a line m ( denoted by Q I m) then Qσ I* mσ ⇔ mσ I Qσ. A (plane) duality which is an isomorphism is called a correlation.[1] The existence of a correlation means that the projective plane C is self-dual.

In the special case that the projective plane is of the PG(2,K) type, with K a division ring, a duality is called a reciprocity.[2] By the Fundamental theorem of projective geometry a reciprocity is the composition of an automorphic function of K and a homography. If the automorphism involved is the identity, then the reciprocity is called a projective correlation.

A correlation of order two (an involution) is called a polarity. If a correlation φ is not a polarity then φ2 is a nontrivial collineation.

This duality mapping concept can also be extended to higher dimensional spaces so the modifier "(plane)" can be dropped in those situations.

Higher dimensional duality

Duality in the projective plane is a special case of duality for projective spaces, transformations of PG(n,K) (also denoted by KPn) with K a field, that interchange objects of dimension r with objects of dimension n - 1 - r ( = codimension r + 1). That is, in a projective space of dimension n, the points (dimension 0) are made to correspond with hyperplanes (codimension 1), the lines joining two points (dimension 1) are made to correspond with the intersection of two hyperplanes (codimension 2), and so on.

The points of PG(n,K) can be taken to be the nonzero vectors in the (n + 1)-dimensional vector space over K, where we identify two vectors which differ by a scalar factor. Another way to put it is that the points of n-dimensional projective space are the lines through the origin in Kn + 1, which are 1-dimensional vector subspaces.[3] Also the n- vector dimensional subspaces of Kn + 1 represent the (n − 1)- geometric dimensional hyperplanes of projective n-space over K.

A nonzero vector u = (u0,u1,...,un) in Kn + 1 also determines an (n - 1) - geometric dimensional subspace (hyperplane) Hu, by

Hu = {(x0,x1,...,xn) : u0x0 + … + unxn = 0 }.

When a vector u is used to define a hyperplane in this way it shall be denoted by uH, while if it is designating a point we will use uP. In terms of the usual dot product, Hu = {xP : uHxP = 0}. Since K is a field, the dot product is symmetrical, meaning uHxP = u0x0 + u1x1 + ... + unxn = x0u0 + x1u1 + ... + xnun = xHuP. A reciprocity can be given by uP ↔ Hu between points and hyperplanes. This extends to a reciprocity between the line generated by two points and the intersection of two such hyperplanes, and so forth.

In the projective plane, PG(2,K), with K a field we have the reciprocity given by: points in homogeneous coordinates (a,b,c) ↔ lines with equations ax + by + cz = 0. In a corresponding projective space, PG(3,K), a reciprocity is given by: points in homogeneous coordinates (a,b,c,d) ↔ planes with equations ax + by + cz + dw = 0. This reciprocity would also map a line determined by two points (a1,b1,c1,d1) and (a2,b2,c2,d2) to the line which is the intersection of the two planes with equations a1x + b1y + c1z + d1w = 0 and a2x + b2y + c2z + d2w = 0.

Three dimensions

In a polarity of real projective 3-space, PG(3,R), points correspond to planes, and lines correspond to lines. By restriction the duality of polyhedra in solid geometry is obtained, where points are dual to faces, and sides are dual to sides, so that the icosahedron is dual to the dodecahedron, and the cube is dual to the octahedron.

Geometric construction of a reciprocity

The reciprocity of PG(2,R), given by homogeneous coordinates can also be described geometrically. This uses the model of the real projective plane which is a "unit sphere with antipodes[4] identified", or equivalently, the model of lines and planes through the origin of the vector space R3. Associate a line through the origin with the unique plane through the origin which is perpendicular (orthogonal) to the line. When, in the model, these lines are considered to be the points and the planes the lines of the projective plane PG(2,R), this association becomes a reciprocity (actually a polarity) of the projective plane. The sphere model is obtained by intersecting the lines and planes through the origin with a unit sphere centered at the origin. The lines meet the sphere in antipodal points which must then be identified to obtain a point of the projective plane, and the planes meet the sphere in great circles which are thus the lines of the projective plane.

That this association "preserves" incidence is most easily seen from the lines and planes model. A point incident with a line in the projective plane corresponds to a line lying in a plane in the model. Applying the association, the plane becomes a line through the origin perpendicular to the plane it is associated with. This image line is perpendicular to every line of the plane which passes through the origin, in particular the original line (point of the projective plane). All lines that are perpendicular to the original line at the origin lie in the unique plane which is orthogonal to the original line, that is, the image plane under the association. Thus, the image line lies in the image plane and the association preserves incidence.

Poles and polars

Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church.

Pole and polar with respect to circle O. P = Q', q is polar of Q, Q is pole of q.

In the Euclidean plane, fix a circle C with center O and radius r. For each point P other than O define an image point P so that OPOP = r2. The mapping defined by PP is called inversion with respect to circle C. The line through P which is perpendicular to the line OP is called the polar of the point P with respect to circle C. Let m be a line not passing through O. Drop a perpendicular from O to m, meeting m at the point Q (this is the point of m that is closest to O). The image of Q under inversion with respect to C is called the pole of m. If a point P (different from O) is on a line m (not passing through O) then the pole of m lies on the polar of P and viceversa. The incidence preserving process, in which points and lines are transformed into their polars and poles with respect to C is called reciprocation.[5] In order to turn this process into a reciprocity, the Euclidean plane (which is not a projective plane) needs to be expanded to the extended euclidean plane by adding a line at infinity and points at infinity which lie on this line. In this expanded plane, we define the polar of the point O to be the line at infinity (and O is the pole of the line at infinity), and the poles of the lines through O are the points of infinity where, if a line has slope s (≠ 0) its pole is the infinite point associated to the parallel class of lines with slope -1/s. The pole of the x-axis is the point of infinity of the vertical lines and the pole of the y-axis is the point of infinity of the horizontal lines.

The construction of a reciprocity based on inversion in a circle given above can be generalized by using inversion in a conic section (in the extended real plane). The reciprocities constructed in this manner are projective correlations of order two, that is, polarities.

Mapping the sphere onto the plane

The unit sphere modulo −1 model of the projective plane is isomorphic (w.r.t. incidence properties) to the planar model: the affine plane extended with a projective line at infinity.

To map a point on the sphere to a point on the plane, let the plane be tangent to the sphere at some point which shall be the origin of the plane's coordinate system (2-D origin). Then construct a line passing through the center of the sphere (3-D origin) and the point on the sphere. This line intersects the plane at a point which is the projection of the point on the sphere onto the plane (or vice versa).

This projection can be used to define a one-to-one onto mapping

If points in are expressed in homogeneous coordinates, then

Also, lines in the planar model are projections of great circles of the sphere. This is so because through any line in the plane pass an infinitude of different planes: one of these planes passes through the 3-D origin, but a plane passing through the 3-D origin intersects the sphere along a great circle.

As we have seen, any great circle in the unit sphere has a projective point perpendicular to it, which can be defined as its dual. But this point is a pair of antipodal points on the unit sphere, through both of which passes a unique 3-D line, and this line extended past the unit sphere intersects the tangent plane at a point, which means that there is a geometric way to associate a unique point on the plane to every line on the plane, such that the point is the dual of the line.

Duality mapping defined

Given a line L in the projective plane, what is its dual point? Draw a line L′ passing through the 2-D origin and perpendicular to line L. Then pick a point P on line L′ on the other side of the origin from line L, such that the distance of point P to the origin is the reciprocal of the distance of line L to the origin.

Figure 1. Three pairs of dual points and lines: one red pair, one yellow pair,
and one blue pair. The duality is an isomorphism of incidence, so that, e.g.,
the line passing through the red and yellow points is dual to the intersection
of the red and yellow lines.

Expressed algebraically, let g be a one-to-one mapping from the projective plane onto itself:

such that

and

where the L subscript is used to semantically distinguish line coordinates from point coordinates. In words, affine line (m, b) with slope m and y-intercept b is the dual of point (m/b, −1/b). If b=0 then the line passes through the 2-D origin and its dual is the ideal point [m : −1 : 0].

The affine point with Cartesian coordinates (x,y) has as its dual the line whose slope is −x/y and whose y-intercept is −1/y. If the point is the 2-D origin [0:0:1], then its dual is [0:1:0]L which is the line at infinity. If the point is [x:0:1], on the x-axis, then its dual is line [x:1:0]L which shall be interpreted as a line whose slope is vertical and whose x-intercept is −1/x.

If a point or a line's homogeneous coordinates are represented as a vector in 3x1 matrix form, then the duality mapping g can be represented by a 3x3 matrix

whose inverse is

Matrix G has one real eigenvalue: one, whose eigenvector is [1:0:0]. The line [1:0:0]L is the y-axis, whose dual is the ideal point [1:0:0] which is the intersection of the ideal line with the x-axis.

Notice that [1:0:0]L is the y-axis, [0:1:0]L is the line at infinity, and [0:0:1]L is the x-axis. In 3-space, matrix G is a 90° rotation about the x-axis which turns the y-axis into the z-axis. In projective 2-space, matrix G is a projective transformation which maps points to points, lines to lines, conic sections to conic sections: it exchanges the line at infinity with the x-axis and maps the y-axis onto itself through a Möbius transformation. As a duality, matrix G pairs up each projective line with its dual projective point.

Preservation of incidence

The duality mapping g is an isomorphism with respect to the incidence properties (such as collinearity and concurrency). The mapping g has this property: given a pair of lines L1 and L2 which intersect at a point P, then their dual points gL1 and gL2 define the unique line g−1P:

.

Given points P1 and P2 through which passes line L, P1.P2 = L, then what is the intersection of lines g−1P1 and g−1P2? If g−1P1g−1P2 = P then

so that

Given a pair of affine points in homogeneous coordinates, the line passing through them is

where the cross product is computed just as it would for an ordinary pair vectors in 3-space.

From this last equation can be derived the intersection of lines, by using the mapping g to "plug in" the lines into the slots for points:

where mapping g is seen to distribute with respect to the cross product: i.e. g is an isomorphism of cross product.

Theorem. The duality mapping g is an isomorphism of cross product. I.e. g is distributive w.r.t. cross product.

Proof. Given points A=(a:b:c) and B=(d:e:f), their cross product is but

.

Therefore

.

Q.E.D.

Notes

43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.

See also

References

  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • F. Bachmann, 1959. Aufbau der Geometrie aus dem Spiegelungsbegriff, Springer, Berlin.
  • 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
  • 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
  • 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
  • Coxeter, H. S. M., 1995. The Real Projective Plane, 3rd ed. Springer Verlag.
  • Coxeter, H. S. M., 2003. Projective Geometry, 2nd ed. Springer Verlag. ISBN 978-0-387-40623-7.
  • 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
  • Greenberg, M.J., 2007. Euclidean and non-Euclidean geometries, 4th ed. Freeman.
  • Hartshorne, Robin, 2009. Foundations of Projective Geometry, 2nd ed. Ishi Press. ISBN 978-4-87187-837-1
  • Hartshorne, Robin, 2000. Geometry: Euclid and Beyond. Springer.
  • Hilbert, D. and Cohn-Vossen, S., 1999. Geometry and the imagination, 2nd ed. Chelsea.
  • D. R. Hughes and F. C. Piper, 1973. Projective Planes, Springer.
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
  • One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
  • 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.

    My blog: http://www.primaboinca.com/view_profile.php?userid=5889534

External links



I had like 17 domains hosted on single account, and never had any special troubles. If you are not happy with the service you will get your money back with in 45 days, that's guaranteed. But the Search Engine utility inside the Hostgator account furnished an instant score for my launched website. Fantastico is unable to install WordPress in a directory which already have any file i.e to install WordPress using Fantastico the destination directory must be empty and it should not have any previous installation files. When you share great information, others will take note. Once your hosting is purchased, you will need to setup your domain name to point to your hosting. Money Back: All accounts of Hostgator come with a 45 day money back guarantee. If you have any queries relating to where by and how to use Hostgator Discount Coupon, you can make contact with us at our site. If you are starting up a website or don't have too much website traffic coming your way, a shared plan is more than enough. Condition you want to take advantage of the worldwide web you prerequisite a HostGator web page, -1 of the most trusted and unfailing web suppliers on the world wide web today. Since, single server is shared by 700 to 800 websites, you cannot expect much speed.



Hostgator tutorials on how to install Wordpress need not be complicated, especially when you will be dealing with a web hosting service that is friendly for novice webmasters and a blogging platform that is as intuitive as riding a bike. After that you can get Hostgator to host your domain and use the wordpress to do the blogging. Once you start site flipping, trust me you will not be able to stop. I cut my webmaster teeth on Control Panel many years ago, but since had left for other hosting companies with more commercial (cough, cough) interfaces. If you don't like it, you can chalk it up to experience and go on. First, find a good starter template design. When I signed up, I did a search for current "HostGator codes" on the web, which enabled me to receive a one-word entry for a discount. Your posts, comments, and pictures will all be imported into your new WordPress blog.

  1. Template:Harvnb pg.151.
  2. Template:Harvnb
  3. Dimension is being used here in two different senses. When referring to a projective space, the term is used in the common geometric way where lines are 1-dimensional and planes are 2-dimensional objects. However, when applied to a vector space, dimension means the number of vectors in a basis, and a basis for a vector subspace thought of as a line has two vectors in it, while a basis for a vector space thought of as a plane has three vectors in it. If the meaning is not clear from the context, the terms projective or geometric are applied to the projective space concept while algebraic or vector are applied to the vector space one. The relation between the two is simply: algebraic dimension = geometric dimension + 1.
  4. the points of a sphere at opposite ends of a diameter are called antipodal points.
  5. Template:Harvnb pg.133