If M is a Riemannian manifold and E a vector bundle over M, then there is a Laplacian operator acting on the k-forms with values in E. If the eigenvalues on k-forms are λj then the zeta function ζk is defined to be
for s large, and this is extended to all complex s by analytic continuation.
The zeta regularized determinant of the Laplacian acting on k-forms is
which is formally the product of the positive eigenvalues of the laplacian acting on k-forms.
The analytic torsionT(M,E) is defined to be
for all n. If we fix a cellular basis for and an orthogonal -basis for , then is a contractible finite based free -chain complex. Let be any chain contraction of D*, i.e. for all . We obtain an isomorphism with , . We define the Reidemeister torsion
where A is the matrix of with respect to the given bases. The Reidemeister torsion is independent of the choice of the cellular basis for , the orthogonal basis for and the chain contraction .
Let be a compact smooth manifold, and let be a unimodular representation. has a smooth triangulation. For any choice of a volume , we get an invariant . Then we call the positive real number the Reidemeister torsion of the manifold with respect to and .
A short history of Reidemeister torsionedit
Reidemeister torsion was first used to combinatorially classify 3-dimensional lens spaces in (Reidemeister 1935) by Reidemeister, and in higher-dimensional spaces by Franz. The classification includes examples of homotopy equivalent 3-dimensional manifolds which are not homeomorphic — at the time (1935) the classification was only up to PL homeomorphism, but later E.J. Brody (1960) showed that this was in fact a classification up to homeomorphism.
J. H. C. Whitehead defined the "torsion" of a homotopy equivalence between finite complexes. This is a direct generalization of the Reidemeister, Franz, and de Rham concept; but is a more delicate invariant. Whitehead torsion provides a key tool for the study of combinatorial or differentiable manifolds with nontrivial fundamental group and is closely related to the concept of "simple homotopy type", see (Milnor 1966)
In 1960 Milnor discovered the duality relation of torsion invariants of manifolds and show that the (twisted) Alexander polynomial of knots is the Reidemeister torsion of its knot complement in . (Milnor 1962) For each q the Poincaré duality induces
and then we obtain
The representation of the fundamental group of knot complement plays a central role in them. It gives the relation between knot theory and torsion invariants.
Cheeger–Müller theoremedit
Let be an orientable compact Riemann manifold of dimension n and a representation of the fundamental group of on a real vector space of dimension N. Then we can define the de Rham complex
and the formal adjoint and due to the flatness of . As usual, we also obtain the Hodge Laplacian on p-forms
Assuming that , the Laplacian is then a symmetric positive semi-positive elliptic operator with pure point spectrum
As before, we can therefore define a zeta function associated with the Laplacian on by
where is the projection of onto the kernel space of the Laplacian . It was moreover shown by (Seeley 1967) that extends to a meromorphic function of which is holomorphic at .
As in the case of an orthogonal representation, we define the analytic torsion by
In 1971 D.B. Ray and I.M. Singer conjectured that for any unitary representation . This Ray–Singer conjecture was eventually proved, independently, by Cheeger (1977, 1979) and Müller (1978). Both approaches focus on the logarithm of torsions and their traces. This is easier for odd-dimensional manifolds than in the even-dimensional case, which involves additional technical difficulties. This Cheeger–Müller theorem (that the two notions of torsion are equivalent), along with Atiyah–Patodi–Singer theorem, later provided the basis for Chern–Simons perturbation theory.
A proof of the Cheeger-Müller theorem for arbitrary representations was later given by J. M. Bismut and Weiping Zhang. Their proof uses the Witten deformation.
Referencesedit
Bismut, J. -M.; Zhang, W. (1994-03-01), "Milnor and Ray-Singer metrics on the equivariant determinant of a flat vector bundle", Geometric & Functional Analysis, 4 (2): 136–212, doi:10.1007/BF01895837, ISSN 1420-8970, S2CID 121327250
Brody, E. J. (1960), "The topological classification of the lens spaces", Annals of Mathematics, 2, 71 (1): 163–184, doi:10.2307/1969884, JSTOR 1969884, MR 0116336
Müller, Werner (1978), "Analytic torsion and R-torsion of Riemannian manifolds", Advances in Mathematics, 28 (3): 233–305, doi:10.1016/0001-8708(78)90116-0, MR 0498252
Nicolaescu, Liviu I. (2002), Notes on the Reidemeister torsion(PDF) Online book
Nicolaescu, Liviu I. (2003), The Reidemeister torsion of 3-manifolds, de Gruyter Studies in Mathematics, vol. 30, Berlin: Walter de Gruyter & Co., pp. xiv+249, doi:10.1515/9783110198102, ISBN 3-11-017383-2, MR 1968575
Ray, Daniel B.; Singer, Isadore M. (1973b), "Analytic torsion.", Partial differential equations, Proc. Sympos. Pure Math., vol. XXIII, Providence, R.I.: Amer. Math. Soc., pp. 167–181, MR 0339293
Ray, Daniel B.; Singer, Isadore M. (1971), "R-torsion and the Laplacian on Riemannian manifolds.", Advances in Mathematics, 7 (2): 145–210, doi:10.1016/0001-8708(71)90045-4, MR 0295381
Reidemeister, Kurt (1935), "Homotopieringe und Linsenräume", Abh. Math. Sem. Univ. Hamburg, 11: 102–109, doi:10.1007/BF02940717, S2CID 124078064
de Rham, Georges (1936), "Sur les nouveaux invariants topologiques de M. Reidemeister", Recueil Mathématique (Matematicheskii Sbornik), Nouvelle Série, 1 (5): 737–742, Zbl 0016.04501
Turaev, Vladimir (2002), Torsions of 3-dimensional manifolds, Progress in Mathematics, vol. 208, Basel: Birkhäuser Verlag, pp. x+196, doi:10.1007/978-3-0348-7999-6, ISBN 3-7643-6911-6, MR 1958479
Mazur, Barry. "Remarks on the Alexander polynomial" (PDF).
Seeley, R. T. (1967), "Complex powers of an elliptic operator", in Calderón, Alberto P. (ed.), Singular Integrals (Proc. Sympos. Pure Math., Chicago, Ill., 1966), Proceedings of Symposia in Pure Mathematics, vol. 10, Providence, R.I.: Amer. Math. Soc., pp. 288–307, ISBN 978-0-8218-1410-9, MR 0237943