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== So the problem there ==
A '''topological quantum field theory''' (or '''topological field theory''' or '''TQFT''') is a [[quantum field theory]] which computes [[topological invariant]]s.


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Although TQFTs were invented by physicists, they are also of mathematical interest, being related to, among other things, [[knot theory]] and the theory of [[four-manifold]]s in [[algebraic topology]], and to the theory of [[moduli spaces]] in [[algebraic geometry]]. [[Simon Donaldson|Donaldson]], [[Vaughan Jones|Jones]], [[Edward Witten|Witten]], and [[Maxim Kontsevich|Kontsevich]] have all won [[Fields Medal]]s for work related to topological field theory.
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== the dark one ==
In [[condensed matter physics]], topological quantum field theories are the low energy effective theories of [[topological order|topologically ordered]] states, such as [[Quantum Hall Effect|fractional quantum Hall]] states, [[string-net]] condensed states, and other [[Strongly correlated quantum spin liquid|strongly correlated quantum liquid]] states.


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==Overview==
相关的主题文章:
In a topological field theory, the [[Correlation function (quantum field theory)|correlation functions]] do not depend on the [[Metric tensor (general relativity)|metric]] of spacetime. This means that the theory is not sensitive to changes in the shape of spacetime; if the spacetime warps or contracts, the correlation functions do not change. Consequently, they are topological invariants.
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</ul>


== what happened ==
Topological field theories are not very interesting on the flat [[Minkowski spacetime]] used in particle physics. Minkowski space can be [[contractible space|contracted to a point]], so a TQFT on Minkowski space computes only trivial topological invariants. Consequently, TQFTs are usually studied on curved spacetimes, such as, for example, [[Riemann surfaces]]. Most of the known topological field theories are [[quantum field theory in curved spacetime|defined on spacetimes]] of dimension less than five. It seems that a few higher dimensional theories exist, but they are not very well understood.


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Quantum gravity is believed to be [[background independence|background-independent]] (in some suitable sense), and TQFTs provide examples of background independent quantum field theories. This has prompted ongoing theoretical investigation of this class of models.
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== he did not dare do not pay attention ==
(Caveat: It is often said that TQFTs have only finitely many degrees of freedom. This is not a fundamental property. It happens to be true in most of the examples that physicists and mathematicians study, but it is not necessary. A topological [[sigma model]] with target infinite-dimensional projective space, if such a thing could be defined, would have countably infinitely many degrees of freedom.)


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==Specific models==
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The known topological field theories fall into two general classes: Schwarz-type TQFTs and Witten-type TQFTs. Witten TQFTs are also sometimes referred to as cohomological field theories.
  <ul>
 
 
===Schwarz-type TQFTs===
  <li>[http://toolbox-music.at/cgibin/gbook/guestbook.cgi http://toolbox-music.at/cgibin/gbook/guestbook.cgi]</li>
In Schwarz-type TQFTs, the [[correlation function (quantum field theory)|correlation function]]s or [[partition function (quantum field theory)|partition function]]s of the system are computed by the path integral of metric independent action functionals. For instance, in the [[BF model]], the spacetime is a two-dimensional manifold M, the observables are constructed from a two-form F, an auxiliary scalar B, and their derivatives. The action (which determines the path integral) is
 
 
  <li>[http://wnbsxdpf.org.cn/plus/feedback.php?aid=105 http://wnbsxdpf.org.cn/plus/feedback.php?aid=105]</li>
:<math>S=\int_M B F\,</math>
 
 
  <li>[http://www.1ny.com.cn/plus/view.php?aid=118523 http://www.1ny.com.cn/plus/view.php?aid=118523]</li>
The spacetime metric does not appear anywhere in the theory, so the theory is explicitly topologically invariant. The first example appeared in 1977 and is due to A. Schwarz, its action functional is:
 
 
</ul>
:<math>\int_M A\wedge dA.</math>
 
Another more famous example is [[Chern-Simons theory]], which can be used to compute [[knot invariant]]s. In general partition functions depend on metric but the above examples are shown to be independent on metric.
 
===Witten-type TQFTs===
The first example of the topological field theories of Witten-type appeared in Witten's paper in 1988 {{Harv|Witten|1988a}}, i.e. topological Yang–Mills theory in four dimensions. Though its action functional contains metric ''g''<sub>αβ</sub>, after [[Topological_string_theory#The topological twist|topological twist]] it turns out to be metric independent. The independence of Stress-energy tensor ''T''<sup>αβ</sup> of the system on metric depends on whether [[BRST quantization|BRST-operator]] is closed. Following Witten's example a lot of examples are found in [[Topological_string_theory|string theory]].
 
==Mathematical formulations==
===The original Atiyah-Segal axioms===
[[Michael Atiyah|Atiyah]] suggested a set of axioms for topological quantum field theory {{Harv|Atiyah|1988a}} which was inspired by [[Graeme Segal|Segal]]'s proposed axioms for [[conformal field theory]], and Witten's idea of the geometric meaning of supersymmetry, {{Harv|Witten|1982}}. Atiyah's axioms are constructed on gluing the boundary with differentiable (topological or continuous) transformation, while Segal's are with conformal transformation. These axioms have been relatively useful for mathematical treatments of Schwarz-type QFTs, although it isn't clear that they capture the whole structure of Witten-type QFTs.  The basic idea is that a TQFT is a [[functor]] from a certain [[category (mathematics)|category]] of [[cobordism]]s to the category of [[vector space]]s.
 
There are in fact two different sets of axioms which could reasonably be called the Atiyah axioms. These axioms differ basically in whether or not they study a TQFT defined on a single fixed ''n''-dimensional Riemannian / Lorentzian spacetime ''M'' or a TQFT defined on all ''n''-dimensional spacetimes at once.
 
Let Λ be a [[commutative ring]] with 1 (for almost all real-world purposes we will have Λ = '''Z''', '''R''' or '''C'''). Atiyah originally proposed the axioms of a topological quantum field theory (TQFT) in dimension ''d'' defined over a ground ring Λ as following:
 
* A finitely generated Λ-module ''Z''(Σ) associated to each oriented closed smooth d-dimensional manifold Σ (corresponding to the ''[[homotopy]]'' axiom),
* An element ''Z''(''M'') ∈ ''Z''(∂''M'') associated to each oriented smooth (''d''+1)-dimensional manifold (with boundary) ''M'' (corresponding to an ''additive'' axiom).
 
These data are subject to the following axioms (4 and 5 were added by Atiyah):
 
#''Z'' is ''functorial'' with respect to orientation preserving [[diffeomorphisms]] of Σ and ''M'',
#''Z'' is ''involutory'', i.e. ''Z''(Σ*) = ''Z''(Σ)* where Σ* is Σ with opposite orientation and ''Z''(Σ)* denotes the dual module,
#''Z'' is ''multiplicative''.
#''Z''(φ) = Λ for the d-dimensional empty manifold and ''Z''(φ) = 1 for the (''d''+1)-dimensional empty manifold.
#''Z''(''M*'') = {{overline|''Z''(''M'')}} (the ''[[hermitian]]'' axiom). Equivalently, ''Z''(''M*'') is the disjoint of ''Z''(''M'')
 
'''Remark.''' If for a closed manifold ''M'' we view ''Z''(''M'') as a numerical invariant, then for a manifold with boundary we should think of ''Z''(''M'') ∈ ''Z''(∂''M'') as a "relative" invariant. Let ''f'' : Σ × ''I'' → Σ × ''I'' be an orientation preserving diffeomorphism, and identify opposite ends of Σ × ''I'' by ''f''. This gives a manifold Σ<sub>''f''</sub> and our axioms imply
:<math>Z(\Sigma_f)=\text{Trace}\ \Sigma(f)</math>
where Σ(''f'') is the induced automorphism of ''Z''(Σ).
 
'''Remark.''' For a manifold ''M'' with boundary Σ we can always form the double <math>M\cup_\Sigma M^*</math> which is a closed manifold. The fifth shows that
:<math>Z(M\cup_\Sigma M^*)=|Z(M)|^2</math>
where on the right we compute the norm in the hermitian (possibly indefinite) metric.
 
===The relation to physics===
Physically (2)+(4) is related to relativistic invariance while (3)+(5) is indicative of the quantum nature of the theory.
 
Σ is meant to indicate the physical space (usually, ''d'' = 3 for standard physics) and the extra dimension in Σ × ''I'' is "imaginary" time. The space ''Z''(''M'') is the [[Hilbert space]] of the quantum theory and a physical theory, with a [[Hamiltonian (quantum_mechanics)|Hamiltonian]] ''H'', will have an time evolution operator ''e<sup>itH</sup>'' or an "imaginary time" operator ''e<sup>−tH</sup>''. The main feature of ''topological'' QFTs is that ''H'' = 0, which implies that there is no real dynamics or propagation, along the cylinder Σ × ''I''. However, there can be non-trivial "propagation" (or tunneling amplitudes) from Σ<sub>0</sub> to Σ<sub>1</sub> through an intervening manifold ''M'' with <math>\partial M=\Sigma^*_0\cup\Sigma_1</math>; this reflects the topology of ''M''.
 
If ∂''M'' = Σ, then the distinguished vector ''Z''(''M'') in the Hilbert space ''Z''(Σ) is thought of as the ''vacuum state'' defined by ''M''. For a closed manifold ''M'' the number ''Z''(''M'') is the [[vacuum expectation value]]. In analogy with [[statistical mechanics]] it is also called the [[partition function]].
 
The reason why a theory with zero Hamiltonian can be sensibly formulated in the [[Feynman path integral]] approach to QFT. This incorporates relativistic invariance (which caters for general (''d''+1)-dimensional "spacetimes") and the theory is formally defined by writing down a suitable [[Lagrangian]] - a functional of the classical fields of the theory. A Lagrangian which involves only first derivatives in time formally leads to a zero Hamiltonian, but the Lagrangian itself may have non-trivial features which relate it to the topology of ''M''.
 
===Atiyah's examples===
In 1988, M. Atiyah published a paper in which he described many new examples of topological quantum field theory that were considered at that time. {{Harv|Atiyah|1988}} It contains some new [[topological invariant]]s and the new ideas, which are [[Casson invariant]], [[Donaldson invariant]], [[Geometric group theory|Gromov's theory]], [[Floer homology]] and [[Jones polynomial|Jones-Witten's theory]].
 
====''d'' = 0====
In this case Σ consists of finitely many points. To single point we associate a vector space ''V'' = ''Z''(point) and to ''n''-points the ''n''-fold tensor product: ''V''<sup>⊗''n''</sup> = ''V''&nbsp;⊗&nbsp;...&nbsp;⊗&nbsp;''V''. The [[symmetric group]] ''S<sub>n</sub>'' acts on ''V''<sup>⊗''n''</sup>. A standard way to get the quantum Hilbert space is to give a classical [[symplectic manifold]] (or [[phase space]]) and then quantize it. Let us extend ''S<sub>n</sub>'' to compact Lie group ''G'' and consider "integrable" orbits for which the symplectic structure comes from a [[line bundle]] then quantization leads to the irreducible representations ''V'' of ''G''. This is the physical interpretation of the [[Borel-Weil theorem]] or the [[Borel-Weil-Bott theorem]]. The Lagrangian of these theories is the classical action ([[holonomy]] of the line bundle). Thus topological QFT's with ''d'' = 0 relate naturally to the classical [[representation theory]] of [[Lie group]]s and [[symmetric group]]s.
 
====''d'' = 1====
We should consider periodic boundary conditions given by closed loops in a compact symplectic manifold ''X''. Along to {{Harv|Witten|1982}} holonomy round such loops used in the case of ''d'' = 0 as a Lagrangian is used to modify the Hamiltonian. For a closed surface ''M'' the invariant ''Z''(''M'') of the theory is the number of [[pseudoholomorphic curve|pseudo holomorphic map]]s ''f'' : ''M'' → ''X'' in the sense of Gromov (they are ordinary [[holomorphic map]]s if ''X'' is a [[Kaehler manifold]]). If this number becomes to infinite i.e. if there are "moduli", then we must fix further data on ''M''. This can be done by picking some points ''P<sub>i</sub>'' and then looking at holomorphic maps ''f'' : ''M'' → ''X'' with ''f''(''P<sub>i</sub>'') constrained to lie on a fixed hyperplane. {{Harv|Witten|1988b}} has written down the relevant Lagrangian for this theory. Floer has given a rigorous treatment, i.e. [[Floer homology]], based on {{Harv|Witten|1982}}'s [[Morse theory]] ideas, for the case when the boundary conditions are the interval instead of periodic, the initial and end-points of paths lie on two fixed [[Lagrangian submanifold]]s. This theory has been developed as [[Gromov-Witten invariant]] theory.
 
Another example is [[Holomorphic]] [[Conformal Field Theory]]. This might not be strictly topological quantum field theory at that time because Hilbert spaces are infinite dimensional. The conformal field theories are also related to compact Lie group ''G'' in which the classical phase consists of a central extension of the [[loop group]] ''LG''. Quantizing these produces the Hilbert spaces of the theory of irreducible (projective) representations of ''LG''. The group Diff<sub>+</sub>('''S'''<sup>1</sup>) now substitutes for the symmetric group and play an important role. The partition function in such theories depends on [[complex structure]]{{disambiguation needed|date=September 2012}}: it is not purely topological.
 
====''d'' = 2====
Jones-Witten theory is the most important theory in this case. Here the classical phase space, associated to a closed surface Σ is the moduli space of flat ''G''-bundle over Σ. The Lagrangian is an integer multiple of the [[Chern-Simons theory|Chern-Simons function]] of a ''G''-connection on a 3-manifold (which has to be "framed"). The integer multiple ''k'', called the level, is a parameter of the theory and ''k'' → ∞ gives the classical limit. This theory can be naturally coupled with the ''d'' = 0 theory to produce a "relative" theory. The details have been described by Witten who shows that partition function for a (framed) link in the 3-sphere is just the value of the [[Jones polynomial]] for a suitable root of unity. The theory can be defined over the relevant [[cyclotomic field]]. By considering [[Riemann surface]] with boundary, we can couple it to the ''d'' = 1 conformal theory instead of coupling ''d'' = 2 theory to ''d'' = 0. This theory has been developed as the Jones-Witten theory and turned out to be the trigger binding the [[knot theory]] and the quantum theory.
 
====''d'' = 3====
Donaldson has defined integer invariant of smooth 4-manifolds by using moduli spaces of SU(2)-instantons. These invariants are polynomials on the second homology. Thus 4-manifolds should have extra data consisting of the symmetric algebra of ''H''<sub>2</sub>. {{Harv|Witten|1988a}} has produced a super-symmetric Lagrangian which formally reproduces the Donaldson theory. Witten's formula might be understood as an infinite-dimensional analogue of the [[Gauss-Bonnet theorem]]. At a later date, this theory is further developed and become the [[Seiberg-Witten theory|Seiberg-Witten gauge theory]] which reduces SU(2) to U(1) in ''N'' = 2, ''d'' = 4 gauge theory. The Hamiltonian version of the theory has been developed by Floer in terms of the space of connections on a 3-manifold. Floer uses the [[Chern-Simons theory|Chern-Simons function]], which is the Lagrangian of the Jones-Witten theory to modify the Hamiltonian. In detail see {{Harv|Atiyah|1988}}. {{Harv|Witten|1988a}} has also shown how one can couple the ''d'' = 3 and ''d'' = 1 theories together: this is quite analogous to the coupling between ''d'' = 2 and ''d'' = 0 in the Jones-Witten theory.
 
Now, it isn't considered on a fixed dimension but on all the dimensions at the same time, namely, topological field theory is viewed as a [[functor]].
 
===The case of a fixed spacetime===
Let ''Bord<sub>M</sub>'' be the category whose morphisms are ''n''-dimensional [[submanifold]]s of ''M'' and whose objects are [[connected space|connected]] components of the boundaries of such submanifolds. Regard two morphisms as equivalent if they are [[homotopy|homotopic]] via submanifolds of ''M'', and so form the quotient category ''hBord<sub>M</sub>'': The objects in ''hBord<sub>M</sub>'' are the objects of ''Bord<sub>M</sub>'', and the morphisms of ''hBord<sub>M</sub>'' are homotopy equivalence classes of morphisms in ''Bord<sub>M</sub>''.  A TQFT on ''M'' is a [[symmetric monoidal functor]] from ''hBord<sub>M</sub>'' to the category of vector spaces.
 
Note that cobordisms can, if their boundaries match up, be sewn together to form a new bordism.  This is the composition law for morphisms in the cobordism category. Since functors are required to preserve composition, this says that the linear map corresponding to a sewn together morphism is just the composition of the linear map for each piece.
 
There is an [[equivalence of categories]] between the category of 2-dimensional topological quantum field theories and the category of commutative [[Frobenius algebra]]s.
 
===All ''n''-dimensional spacetimes at once===
[[File:Pair of pants cobordism (pantslike).svg|thumb|The [[pair of pants (mathematics)|pair of pants]] is a (1+1)-dimensional bordism, which corresponds to a product or coproduct in a 2-dimensional TQFT.]]
 
To consider all spacetimes at once, it is necessary to replace ''hBord<sub>M</sub>'' by a larger category.  So let ''Bord<sub>n</sub>'' be the category of bordisms, i.e. the category whose morphisms are ''n''-dimensional manifolds with boundary, and whose objects are the connected components of the boundaries of n-dimensional manifolds. (Note that any (''n''−1)-dimensional manifold may appear as an object in ''Bord<sub>n</sub>''.)  As above, regard two morphisms in ''Bord<sub>n</sub>'' as equivalent if they are homotopic, and form the quotient category ''hBord<sub>n</sub>''. ''Bord<sub>n</sub>'' is a  [[monoidal category]] under the operation which takes two bordisms to the bordism made from their disjoint union.  A TQFT on ''n''-dimensional manifolds is then a functor from ''hBord<sub>n</sub>'' to the category of vector spaces, which takes disjoint unions of bordisms to the tensor product of them.
 
For example, for (1+1)-dimensional bordisms (2-dimensional bordisms between 1-dimensional manifolds), the map associated with a [[pair of pants (mathematics)|pair of pants]] gives a product or coproduct, depending on how the boundary components are grouped – which is commutative or cocommutative, while the map associated with a disk gives a counit (trace) or unit (scalars), depending on grouping of boundary, and thus (1+1)-dimension TQFTs correspond to [[Frobenius algebra]]s.
 
Furthermore, we consider simultaneously 4-dimensional, 3-dimensional and 2-dimensional manifolds that are related by the above bordisms, then obtain ample and important examples.
 
===Development at a later time===
Looking at the development of topological quantum field theory we should consider that it has many applications to [[Seiberg-Witten theory|Seiberg-Witten gauge theory]], [[topological string theory]], the relationship between [[knot theory]] and quantum theory, and [[quantum knot invariant]]s. Furthermore it has provided objects of great interest to both mathematics and physics. Also of important recent interest is non-local operators in TQFT.({{harvtxt|Gukov|Kapustin|2013}}) If string theory is viewed as the fundamental, then non-local TQFTs can be viewed as non-physical models that provide a computationally efficient approximation to local string theory.
 
==See also==
*[[Quantum topology]]
*[[Topological defect]]
*[[Topological entropy in physics]]
*[[Topological order]]
*[[Topological quantum number]]
*[[Topological string theory]]
*[[Arithmetic topology]]
*[[Cobordism hypothesis]]
 
==References==
<references />
*{{Citation | last1=Atiyah | first1=Michael | author1-link=Michael Atiyah | title=Topological quantum field theories | url=http://www.numdam.org/item?id=PMIHES_1988__68__175_0 | id={{MathSciNet | id = 1001453}} | year=1989 | journal=[[Publications Mathématiques de l'IHÉS]] | issue=68 | pages=175–186 | doi=10.1007/BF02698547 | volume=68}}
*{{Citation | last1=Witten | first1=Edward | author1-link=Edward Witten | title=Super-symmetry and Morse Theory | url=http://intlpress.com/JDG/archive/1982/17-4-661.pdf | year=1982 | journal=[[J. Diff Geom.]] | pages=661–692 | volume=17}}
* {{Citation | last=Lurie | first=Jacob | title = On the Classification of Topological Field Theories
|url = http://www-math.mit.edu/~lurie/papers/cobordism.pdf }}
*{{Citation | last1=Witten | first1=Edward | author1-link=Edward Witten | title=Topological quantum field theory | url=http://projecteuclid.org/euclid.cmp/1104161738 | id={{MathSciNet | id = 953828}} | year=1988a | journal=Communications in Mathematical Physics | volume=117 | issue=3 | pages=353–386 | doi=10.1007/BF01223371}}
*{{Citation | last1=Witten | first1=Edward | author1-link=Edward Witten | title=Topological sigma models | url=http://prjecteuclid.org/DPubS/Repository/1.0/Disseminate?view=body&id=pdf_1&handle=euclid.cmp/1104162092 | year=1988b | journal=Communications in Mathematical Physics | volume=118 | issue=3 | pages=411–449 }}
*{{Cite journal | last1=Atiyah | first1=Michael | author1-link=Michael Atiyah | title=New invariants of three and four dimensional manifolds | year=1988 | journal=Proc. Symp. Pure Math., 48, American Math. Soc. | pages=285–299 | volume=48}}
*{{Cite journal |first1=Sergei |last1=Gukov |first2=Anton |last2=Kapustin | title=Topological Quantum Field Theory, Nonlocal Operators, and Gapped Phases of Gauge Theories |year=2013 |journal=[[JHEP]] |url=http://inspirehep.net/search?ln=en&ln=en&p=find+a+gukov&of=hb&action_search=Search&sf=&so=d&rm=&rg=25&sc=0 |ref=harv}}
{{Quantum field theories}}
 
[[Category:Quantum field theory]]
[[Category:Topology]]

Revision as of 07:24, 14 May 2013

A topological quantum field theory (or topological field theory or TQFT) is a quantum field theory which computes topological invariants.

Although TQFTs were invented by physicists, they are also of mathematical interest, being related to, among other things, knot theory and the theory of four-manifolds in algebraic topology, and to the theory of moduli spaces in algebraic geometry. Donaldson, Jones, Witten, and Kontsevich have all won Fields Medals for work related to topological field theory.

In condensed matter physics, topological quantum field theories are the low energy effective theories of topologically ordered states, such as fractional quantum Hall states, string-net condensed states, and other strongly correlated quantum liquid states.

Overview

In a topological field theory, the correlation functions do not depend on the metric of spacetime. This means that the theory is not sensitive to changes in the shape of spacetime; if the spacetime warps or contracts, the correlation functions do not change. Consequently, they are topological invariants.

Topological field theories are not very interesting on the flat Minkowski spacetime used in particle physics. Minkowski space can be contracted to a point, so a TQFT on Minkowski space computes only trivial topological invariants. Consequently, TQFTs are usually studied on curved spacetimes, such as, for example, Riemann surfaces. Most of the known topological field theories are defined on spacetimes of dimension less than five. It seems that a few higher dimensional theories exist, but they are not very well understood.

Quantum gravity is believed to be background-independent (in some suitable sense), and TQFTs provide examples of background independent quantum field theories. This has prompted ongoing theoretical investigation of this class of models.

(Caveat: It is often said that TQFTs have only finitely many degrees of freedom. This is not a fundamental property. It happens to be true in most of the examples that physicists and mathematicians study, but it is not necessary. A topological sigma model with target infinite-dimensional projective space, if such a thing could be defined, would have countably infinitely many degrees of freedom.)

Specific models

The known topological field theories fall into two general classes: Schwarz-type TQFTs and Witten-type TQFTs. Witten TQFTs are also sometimes referred to as cohomological field theories.

Schwarz-type TQFTs

In Schwarz-type TQFTs, the correlation functions or partition functions of the system are computed by the path integral of metric independent action functionals. For instance, in the BF model, the spacetime is a two-dimensional manifold M, the observables are constructed from a two-form F, an auxiliary scalar B, and their derivatives. The action (which determines the path integral) is

The spacetime metric does not appear anywhere in the theory, so the theory is explicitly topologically invariant. The first example appeared in 1977 and is due to A. Schwarz, its action functional is:

Another more famous example is Chern-Simons theory, which can be used to compute knot invariants. In general partition functions depend on metric but the above examples are shown to be independent on metric.

Witten-type TQFTs

The first example of the topological field theories of Witten-type appeared in Witten's paper in 1988 Template:Harv, i.e. topological Yang–Mills theory in four dimensions. Though its action functional contains metric gαβ, after topological twist it turns out to be metric independent. The independence of Stress-energy tensor Tαβ of the system on metric depends on whether BRST-operator is closed. Following Witten's example a lot of examples are found in string theory.

Mathematical formulations

The original Atiyah-Segal axioms

Atiyah suggested a set of axioms for topological quantum field theory Template:Harv which was inspired by Segal's proposed axioms for conformal field theory, and Witten's idea of the geometric meaning of supersymmetry, Template:Harv. Atiyah's axioms are constructed on gluing the boundary with differentiable (topological or continuous) transformation, while Segal's are with conformal transformation. These axioms have been relatively useful for mathematical treatments of Schwarz-type QFTs, although it isn't clear that they capture the whole structure of Witten-type QFTs. The basic idea is that a TQFT is a functor from a certain category of cobordisms to the category of vector spaces.

There are in fact two different sets of axioms which could reasonably be called the Atiyah axioms. These axioms differ basically in whether or not they study a TQFT defined on a single fixed n-dimensional Riemannian / Lorentzian spacetime M or a TQFT defined on all n-dimensional spacetimes at once.

Let Λ be a commutative ring with 1 (for almost all real-world purposes we will have Λ = Z, R or C). Atiyah originally proposed the axioms of a topological quantum field theory (TQFT) in dimension d defined over a ground ring Λ as following:

  • A finitely generated Λ-module Z(Σ) associated to each oriented closed smooth d-dimensional manifold Σ (corresponding to the homotopy axiom),
  • An element Z(M) ∈ Z(∂M) associated to each oriented smooth (d+1)-dimensional manifold (with boundary) M (corresponding to an additive axiom).

These data are subject to the following axioms (4 and 5 were added by Atiyah):

  1. Z is functorial with respect to orientation preserving diffeomorphisms of Σ and M,
  2. Z is involutory, i.e. Z(Σ*) = Z(Σ)* where Σ* is Σ with opposite orientation and Z(Σ)* denotes the dual module,
  3. Z is multiplicative.
  4. Z(φ) = Λ for the d-dimensional empty manifold and Z(φ) = 1 for the (d+1)-dimensional empty manifold.
  5. Z(M*) = Template:Overline (the hermitian axiom). Equivalently, Z(M*) is the disjoint of Z(M)

Remark. If for a closed manifold M we view Z(M) as a numerical invariant, then for a manifold with boundary we should think of Z(M) ∈ Z(∂M) as a "relative" invariant. Let f : Σ × I → Σ × I be an orientation preserving diffeomorphism, and identify opposite ends of Σ × I by f. This gives a manifold Σf and our axioms imply

where Σ(f) is the induced automorphism of Z(Σ).

Remark. For a manifold M with boundary Σ we can always form the double which is a closed manifold. The fifth shows that

where on the right we compute the norm in the hermitian (possibly indefinite) metric.

The relation to physics

Physically (2)+(4) is related to relativistic invariance while (3)+(5) is indicative of the quantum nature of the theory.

Σ is meant to indicate the physical space (usually, d = 3 for standard physics) and the extra dimension in Σ × I is "imaginary" time. The space Z(M) is the Hilbert space of the quantum theory and a physical theory, with a Hamiltonian H, will have an time evolution operator eitH or an "imaginary time" operator e−tH. The main feature of topological QFTs is that H = 0, which implies that there is no real dynamics or propagation, along the cylinder Σ × I. However, there can be non-trivial "propagation" (or tunneling amplitudes) from Σ0 to Σ1 through an intervening manifold M with ; this reflects the topology of M.

If ∂M = Σ, then the distinguished vector Z(M) in the Hilbert space Z(Σ) is thought of as the vacuum state defined by M. For a closed manifold M the number Z(M) is the vacuum expectation value. In analogy with statistical mechanics it is also called the partition function.

The reason why a theory with zero Hamiltonian can be sensibly formulated in the Feynman path integral approach to QFT. This incorporates relativistic invariance (which caters for general (d+1)-dimensional "spacetimes") and the theory is formally defined by writing down a suitable Lagrangian - a functional of the classical fields of the theory. A Lagrangian which involves only first derivatives in time formally leads to a zero Hamiltonian, but the Lagrangian itself may have non-trivial features which relate it to the topology of M.

Atiyah's examples

In 1988, M. Atiyah published a paper in which he described many new examples of topological quantum field theory that were considered at that time. Template:Harv It contains some new topological invariants and the new ideas, which are Casson invariant, Donaldson invariant, Gromov's theory, Floer homology and Jones-Witten's theory.

d = 0

In this case Σ consists of finitely many points. To single point we associate a vector space V = Z(point) and to n-points the n-fold tensor product: Vn = V ⊗ ... ⊗ V. The symmetric group Sn acts on Vn. A standard way to get the quantum Hilbert space is to give a classical symplectic manifold (or phase space) and then quantize it. Let us extend Sn to compact Lie group G and consider "integrable" orbits for which the symplectic structure comes from a line bundle then quantization leads to the irreducible representations V of G. This is the physical interpretation of the Borel-Weil theorem or the Borel-Weil-Bott theorem. The Lagrangian of these theories is the classical action (holonomy of the line bundle). Thus topological QFT's with d = 0 relate naturally to the classical representation theory of Lie groups and symmetric groups.

d = 1

We should consider periodic boundary conditions given by closed loops in a compact symplectic manifold X. Along to Template:Harv holonomy round such loops used in the case of d = 0 as a Lagrangian is used to modify the Hamiltonian. For a closed surface M the invariant Z(M) of the theory is the number of pseudo holomorphic maps f : MX in the sense of Gromov (they are ordinary holomorphic maps if X is a Kaehler manifold). If this number becomes to infinite i.e. if there are "moduli", then we must fix further data on M. This can be done by picking some points Pi and then looking at holomorphic maps f : MX with f(Pi) constrained to lie on a fixed hyperplane. Template:Harv has written down the relevant Lagrangian for this theory. Floer has given a rigorous treatment, i.e. Floer homology, based on Template:Harv's Morse theory ideas, for the case when the boundary conditions are the interval instead of periodic, the initial and end-points of paths lie on two fixed Lagrangian submanifolds. This theory has been developed as Gromov-Witten invariant theory.

Another example is Holomorphic Conformal Field Theory. This might not be strictly topological quantum field theory at that time because Hilbert spaces are infinite dimensional. The conformal field theories are also related to compact Lie group G in which the classical phase consists of a central extension of the loop group LG. Quantizing these produces the Hilbert spaces of the theory of irreducible (projective) representations of LG. The group Diff+(S1) now substitutes for the symmetric group and play an important role. The partition function in such theories depends on complex structureTemplate:Disambiguation needed: it is not purely topological.

d = 2

Jones-Witten theory is the most important theory in this case. Here the classical phase space, associated to a closed surface Σ is the moduli space of flat G-bundle over Σ. The Lagrangian is an integer multiple of the Chern-Simons function of a G-connection on a 3-manifold (which has to be "framed"). The integer multiple k, called the level, is a parameter of the theory and k → ∞ gives the classical limit. This theory can be naturally coupled with the d = 0 theory to produce a "relative" theory. The details have been described by Witten who shows that partition function for a (framed) link in the 3-sphere is just the value of the Jones polynomial for a suitable root of unity. The theory can be defined over the relevant cyclotomic field. By considering Riemann surface with boundary, we can couple it to the d = 1 conformal theory instead of coupling d = 2 theory to d = 0. This theory has been developed as the Jones-Witten theory and turned out to be the trigger binding the knot theory and the quantum theory.

d = 3

Donaldson has defined integer invariant of smooth 4-manifolds by using moduli spaces of SU(2)-instantons. These invariants are polynomials on the second homology. Thus 4-manifolds should have extra data consisting of the symmetric algebra of H2. Template:Harv has produced a super-symmetric Lagrangian which formally reproduces the Donaldson theory. Witten's formula might be understood as an infinite-dimensional analogue of the Gauss-Bonnet theorem. At a later date, this theory is further developed and become the Seiberg-Witten gauge theory which reduces SU(2) to U(1) in N = 2, d = 4 gauge theory. The Hamiltonian version of the theory has been developed by Floer in terms of the space of connections on a 3-manifold. Floer uses the Chern-Simons function, which is the Lagrangian of the Jones-Witten theory to modify the Hamiltonian. In detail see Template:Harv. Template:Harv has also shown how one can couple the d = 3 and d = 1 theories together: this is quite analogous to the coupling between d = 2 and d = 0 in the Jones-Witten theory.

Now, it isn't considered on a fixed dimension but on all the dimensions at the same time, namely, topological field theory is viewed as a functor.

The case of a fixed spacetime

Let BordM be the category whose morphisms are n-dimensional submanifolds of M and whose objects are connected components of the boundaries of such submanifolds. Regard two morphisms as equivalent if they are homotopic via submanifolds of M, and so form the quotient category hBordM: The objects in hBordM are the objects of BordM, and the morphisms of hBordM are homotopy equivalence classes of morphisms in BordM. A TQFT on M is a symmetric monoidal functor from hBordM to the category of vector spaces.

Note that cobordisms can, if their boundaries match up, be sewn together to form a new bordism. This is the composition law for morphisms in the cobordism category. Since functors are required to preserve composition, this says that the linear map corresponding to a sewn together morphism is just the composition of the linear map for each piece.

There is an equivalence of categories between the category of 2-dimensional topological quantum field theories and the category of commutative Frobenius algebras.

All n-dimensional spacetimes at once

The pair of pants is a (1+1)-dimensional bordism, which corresponds to a product or coproduct in a 2-dimensional TQFT.

To consider all spacetimes at once, it is necessary to replace hBordM by a larger category. So let Bordn be the category of bordisms, i.e. the category whose morphisms are n-dimensional manifolds with boundary, and whose objects are the connected components of the boundaries of n-dimensional manifolds. (Note that any (n−1)-dimensional manifold may appear as an object in Bordn.) As above, regard two morphisms in Bordn as equivalent if they are homotopic, and form the quotient category hBordn. Bordn is a monoidal category under the operation which takes two bordisms to the bordism made from their disjoint union. A TQFT on n-dimensional manifolds is then a functor from hBordn to the category of vector spaces, which takes disjoint unions of bordisms to the tensor product of them.

For example, for (1+1)-dimensional bordisms (2-dimensional bordisms between 1-dimensional manifolds), the map associated with a pair of pants gives a product or coproduct, depending on how the boundary components are grouped – which is commutative or cocommutative, while the map associated with a disk gives a counit (trace) or unit (scalars), depending on grouping of boundary, and thus (1+1)-dimension TQFTs correspond to Frobenius algebras.

Furthermore, we consider simultaneously 4-dimensional, 3-dimensional and 2-dimensional manifolds that are related by the above bordisms, then obtain ample and important examples.

Development at a later time

Looking at the development of topological quantum field theory we should consider that it has many applications to Seiberg-Witten gauge theory, topological string theory, the relationship between knot theory and quantum theory, and quantum knot invariants. Furthermore it has provided objects of great interest to both mathematics and physics. Also of important recent interest is non-local operators in TQFT.(Template:Harvtxt) If string theory is viewed as the fundamental, then non-local TQFTs can be viewed as non-physical models that provide a computationally efficient approximation to local string theory.

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.

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    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
  • 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
  • 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
  • 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
  • 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

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