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In [[algebraic geometry]], a branch of [[mathematics]], '''Serre duality''' is a [[duality (mathematics)|duality]] present on [[non-singular]] [[projective variety|projective]] [[algebraic variety|algebraic varieties]] ''V'' of dimension ''n'' (and in greater generality for [[vector bundle]]s and further, for [[coherent sheaf|coherent sheaves]]). It shows that a [[cohomology]] group ''H''<sup>''i''</sup> is the [[dual space]] of another one, ''H''<sup>''n''−''i''</sup>. If the variety is defined over the [[complex number]]s, this yields different information from [[Poincaré duality]], which relates ''H''<sup>''i''</sup> to ''H''<sup>2''n''−''i''</sup>, considering ''V'' as a real manifold of dimension 2''n''. | |||
In the case for holomorphic vector bundle ''E'' over a smooth compact complex manifold ''V'', the statement is in the form: | |||
:::<math>H^q(V,E)\cong H^{n-q}(V,K\otimes E^{\ast})^{\ast},</math> | |||
in which ''V'' is not necessarily projective. | |||
==Algebraic curve== | |||
The case of [[algebraic curve]]s was already implicit in the [[Riemann-Roch theorem]]. For a curve ''C'' the coherent groups ''H''<sup>''i''</sup> vanish for ''i'' > 1; but ''H''<sup>1</sup> does enter implicitly. In fact, the basic relation of the theorem involves ''l''(''D'') and ''l''(''K''−''D''), where ''D'' is a [[divisor]] and ''K'' is a divisor of the [[canonical class]]. After [[Jean-Pierre Serre|Serre]] we recognise ''l''(''K''−''D'') as the dimension of ''H''<sup>1</sup>(''D''), where now ''D'' means the [[line bundle]] determined by the divisor ''D''. That is, Serre duality in this case relates groups ''H''<sup>1</sup>(''D'') and ''H''<sup>0</sup>(''KD''*), and we are reading off dimensions (notation: ''K'' is the canonical line bundle, ''D''* is the dual line bundle, and juxtaposition is the [[tensor product]] of line bundles). | |||
In this formulation the Riemann-Roch theorem can be viewed as a computation of the [[Euler characteristic of a sheaf]] | |||
:''h''<sup>0</sup>(''D'') − ''h''<sup>1</sup>(''D''), | |||
in terms of the [[genus (mathematics)|genus]] of the curve, which is | |||
:''h''<sup>1</sup>(''C'',''O''<sub>''C''</sub>), | |||
and the degree of ''D''. It is this expression that can be generalised to higher dimensions. | |||
Serre duality of curves is therefore something very classical; but it has an interesting light to cast. For example, in [[Riemann surface]] theory, the [[deformation theory]] of complex structures is studied classically by means of [[quadratic differential]]s (namely sections of ''L''(''K''<sup>2</sup>)). The [[deformation theory]] of [[Kunihiko Kodaira]] and [[D. C. Spencer]] identifies deformations via ''H''<sup>1</sup>(''T''), where ''T'' is the [[tangent bundle]] sheaf ''K''*. The duality shows why these approaches coincide. | |||
==Origin and generalisations== | |||
The origin of the theory lies in Serre's earlier work on [[several complex variables]]. In the generalisation of [[Alexander Grothendieck]], Serre duality becomes a part of [[coherent duality]] in a much broader setting. While the role of ''K'' above in general Serre duality is played by the [[determinant line bundle]] of the [[cotangent bundle]], when ''V'' is a manifold, in full generality ''K'' cannot merely be a ''single'' sheaf in the absence of some hypothesis of [[non-singular]]ity on ''V''. The formulation in full generality uses a [[derived category]] and [[Ext functor]]s, to allow for the fact that ''K'' is now represented by a [[chain complex]] of sheaves, namely, the dualizing complex. Nevertheless, the statement of the theorem is recognisably Serre's. | |||
==References== | |||
* {{Citation | last1=Hartshorne | first1=Robin | author1-link=Robin Hartshorne | title=[[Algebraic Geometry (book)|Algebraic Geometry]] | publisher=[[Springer-Verlag]] | location=Berlin, New York | isbn=978-0-387-90244-9 | oclc=13348052 | id={{MathSciNet | id = 0463157}} | year=1977}}, see Ch. III.7 | |||
*{{Springer|id=D/d034120|title=Duality}} | |||
* {{Citation | last1=Huybrechts | first1=Daniel | title=Complex geometry| publisher=[[Springer-Verlag]] | location=Berlin | year=2005}}, see p. 171. | |||
* {{Citation | last1=Tate | first1=John | author1-link=John Tate | title=Residues of differentials on curves | url=http://archive.numdam.org/ARCHIVE/ASENS/ASENS_1968_4_1_1/ASENS_1968_4_1_1_149_0/ASENS_1968_4_1_1_149_0.pdf | year=1968 | journal=Annales Scientifiques de l'École Normale Supérieure. Quatrième Série | issn=0012-9593 | volume=1 | pages=149–159}} contains a proof for Serre duality for curves | |||
*[http://rigtriv.wordpress.com/2008/05/29/serre-duality/ Serre duality] at the [[weblog]] [http://rigtriv.wordpress.com/ Rigorous trivialities] | |||
*[http://math.stackexchange.com/questions/2403/precise-connection-between-poincare-duality-and-serre-duality A link between Poincaré and Serre dualities via Hodge theory] on [[Stack exchange]] | |||
[[Category:Topological methods of algebraic geometry]] | |||
[[Category:Complex manifolds]] | |||
[[Category:Duality theories]] |
Revision as of 11:38, 6 December 2013
In algebraic geometry, a branch of mathematics, Serre duality is a duality present on non-singular projective algebraic varieties V of dimension n (and in greater generality for vector bundles and further, for coherent sheaves). It shows that a cohomology group Hi is the dual space of another one, Hn−i. If the variety is defined over the complex numbers, this yields different information from Poincaré duality, which relates Hi to H2n−i, considering V as a real manifold of dimension 2n.
In the case for holomorphic vector bundle E over a smooth compact complex manifold V, the statement is in the form:
in which V is not necessarily projective.
Algebraic curve
The case of algebraic curves was already implicit in the Riemann-Roch theorem. For a curve C the coherent groups Hi vanish for i > 1; but H1 does enter implicitly. In fact, the basic relation of the theorem involves l(D) and l(K−D), where D is a divisor and K is a divisor of the canonical class. After Serre we recognise l(K−D) as the dimension of H1(D), where now D means the line bundle determined by the divisor D. That is, Serre duality in this case relates groups H1(D) and H0(KD*), and we are reading off dimensions (notation: K is the canonical line bundle, D* is the dual line bundle, and juxtaposition is the tensor product of line bundles).
In this formulation the Riemann-Roch theorem can be viewed as a computation of the Euler characteristic of a sheaf
- h0(D) − h1(D),
in terms of the genus of the curve, which is
- h1(C,OC),
and the degree of D. It is this expression that can be generalised to higher dimensions.
Serre duality of curves is therefore something very classical; but it has an interesting light to cast. For example, in Riemann surface theory, the deformation theory of complex structures is studied classically by means of quadratic differentials (namely sections of L(K2)). The deformation theory of Kunihiko Kodaira and D. C. Spencer identifies deformations via H1(T), where T is the tangent bundle sheaf K*. The duality shows why these approaches coincide.
Origin and generalisations
The origin of the theory lies in Serre's earlier work on several complex variables. In the generalisation of Alexander Grothendieck, Serre duality becomes a part of coherent duality in a much broader setting. While the role of K above in general Serre duality is played by the determinant line bundle of the cotangent bundle, when V is a manifold, in full generality K cannot merely be a single sheaf in the absence of some hypothesis of non-singularity on V. The formulation in full generality uses a derived category and Ext functors, to allow for the fact that K is now represented by a chain complex of sheaves, namely, the dualizing complex. Nevertheless, the statement of the theorem is recognisably Serre's.
References
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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.
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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.
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