Let be a closed
manifold with ,
and let
be a circle-valued Morse function. We define an invariant
which counts closed
orbits of the gradient of ,
together with flow lines between the critical points. We show that our invariant
equals a form of topological Reidemeister torsion defined by Turaev [Math. Res. Lett.
4 (1997) 679–695].
We proved a similar result in our previous paper [Topology 38 (1999) 861–888],
but the present paper refines this by separating closed orbits and flow lines according
to their homology classes. (Previously we only considered their intersection numbers
with a fixed level set.) The proof here is independent of the previous proof, and also
simpler.
Aside from its Morse-theoretic interest, this work is motivated by the fact that when
is three-dimensional
and , the invariant
equals a counting
invariant
which was conjectured in our previous paper to equal the Seiberg–Witten invariant of
. Our
result, together with this conjecture, implies that the Seiberg–Witten invariant equals
the Turaev torsion. This was conjectured by Turaev and refines the theorem of Meng
and Taubes [Math. Res. Lett 3 (1996) 661–674].