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In [[mathematics]], a '''translation plane''' is a particular kind of [[projective plane]], as considered as a combinatorial object.<ref>Projective Planes [http://www.maths.qmul.ac.uk/~pjc/pps/pps2.pdf On projective planes]</ref> | |||
In a projective plane, <math>\scriptstyle p</math> represents a point, and <math>\scriptstyle L</math> represents a line. A central [[collineation]] with center <math>\scriptstyle p</math> and axis <math>\scriptstyle L</math> is a collineation fixing every point on <math>\scriptstyle L</math> and every line through <math>\scriptstyle p</math>. It is called an "elation" if <math>\scriptstyle p</math> is on <math>\scriptstyle L</math>, otherwise it is called a "homology". The central collineations with centre <math>\scriptstyle p</math> and axis <math>\scriptstyle L</math> form a group.<ref>Geometry [http://www.math.uni-kiel.de/geometrie/klein/math/geometry/translation.html Translation Plane] Retrieved on June 13, 2007</ref> | |||
A projective plane <math>\scriptstyle \Pi</math> is called a translation plane if there exists a line <math>\scriptstyle L</math> such that the group of elations with axis <math>\scriptstyle L</math> is transitive on the affine plane Π<sub>l</sub> (the [[Affine geometry|affine]] derivative of Π). | |||
== Relationship to spreads == | |||
Translation planes are related to spreads in finite projective spaces by the André/Bruck-Bose construction.<ref>{{cite web|url=http://www-ma4.upc.es/~simeon/bblpsympspread.pdf|title=Symplectice Spreads|last=Ball|first=Simeon|coauthors=John Bamberg, Michel Lavrauw, Tim Penttila|date=2003-09-15|publisher=[[Polytechnic University of Catalonia]]|accessdate=2008-10-08}}</ref> A spread of <math>\scriptstyle PG(3, q) </math> is a set of ''q''<sup>2</sup> + 1 lines, with no two intersecting. Equivalently, it is a partition of the points of <math>\scriptstyle PG(3, q) </math> into lines. | |||
Given a spread <math>\scriptstyle S</math> of <math>\scriptstyle PG(3, q) </math>, the André/Bruck-Bose construction<sup>1</sup> produces a translation plane <math>\scriptstyle \pi(S)</math> of order ''q''<sup>2</sup> as follows: Embed <math>\scriptstyle PG(3, q) </math> as a hyperplane of <math>\scriptstyle PG(4, q) </math>. Define an incidence structure <math>\scriptstyle A(S)</math> with "points," the points of <math>\scriptstyle PG(4, q) </math> not on <math>\scriptstyle PG(3, q) </math> and "lines" the planes of <math>\scriptstyle PG(4, q) </math> meeting <math>\scriptstyle PG(3, q) </math> in a line of <math>\scriptstyle S</math>. Then <math>\scriptstyle A(S)</math> is a translation affine plane of order ''q''<sup>2</sup>. Let <math>\scriptstyle \pi(S)</math> be the projective completion of <math>\scriptstyle A(S)</math>.<ref>{{cite book | |||
| last =André | first =Johannes | authorlink = | coauthors = | title = Über nicht-Dessarguessche Ebenen mit transitiver Translationsgruppe | publisher = | year =1954 | location = | pages =156–186 | url = | doi = | id = }}</ref><ref>{{cite book | |||
| last =Bruck | first = R. H. | authorlink = Richard Bruck| coauthors = R. C. Bose | title = The Construction of Translation Planes from Projective Spaces | publisher = | year =1964 | location = | pages = 85–102 | url = | doi = | id = }}</ref> | |||
==References== | |||
{{Reflist}} | |||
==Further reading== | |||
* Mauro Biliotti, Vikram Jha, Norman L. Johnson (2001) ''Foundations of Translation Planes'', [[Marcel Dekker]] ISBN 0-8247-0609-9 . | |||
==External links== | |||
*[http://www.library.tuiasi.ro/ipm/vol13no34/pure.html Foundations_of_Translation_Planes] | |||
*[http://www-math.ucdenver.edu/~wcherowi/courses/m6221/pglc3a.html Lecture Notes on Projective Geometry] | |||
*[http://mellinger.umwblogs.org/publications/ Publications of Keith Mellinger] | |||
{{DEFAULTSORT:Translation Plane}} | |||
[[Category:Projective geometry]] | |||
Revision as of 19:12, 28 October 2013
In mathematics, a translation plane is a particular kind of projective plane, as considered as a combinatorial object.[1]
In a projective plane, represents a point, and represents a line. A central collineation with center and axis is a collineation fixing every point on and every line through . It is called an "elation" if is on , otherwise it is called a "homology". The central collineations with centre and axis form a group.[2]
A projective plane is called a translation plane if there exists a line such that the group of elations with axis is transitive on the affine plane Πl (the affine derivative of Π).
Relationship to spreads
Translation planes are related to spreads in finite projective spaces by the André/Bruck-Bose construction.[3] A spread of is a set of q2 + 1 lines, with no two intersecting. Equivalently, it is a partition of the points of into lines.
Given a spread of , the André/Bruck-Bose construction1 produces a translation plane of order q2 as follows: Embed as a hyperplane of . Define an incidence structure with "points," the points of not on and "lines" the planes of meeting in a line of . Then is a translation affine plane of order q2. Let be the projective completion of .[4][5]
References
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Further reading
- Mauro Biliotti, Vikram Jha, Norman L. Johnson (2001) Foundations of Translation Planes, Marcel Dekker ISBN 0-8247-0609-9 .
External links
- Foundations_of_Translation_Planes
- Lecture Notes on Projective Geometry
- Publications of Keith Mellinger
- ↑ Projective Planes On projective planes
- ↑ Geometry Translation Plane Retrieved on June 13, 2007
- ↑ Template:Cite web
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