Refinement of Novikov–Betti numbers and of Novikov homology provided by an angle valued map
D. Burghelea Department of Mathematics, The Ohio State University, Columbus, OH 43210, USA
Abstract:
To a pair
$(X,f)$,
$X$ compact ANR and
$f\colon X\to \mathbb S^1$ a continuous angle valued map,
$\kappa$ a field, and a nonnegative integer
$r$, one assigns a finite configuration of complex numbers
$z$ with multiplicities
$\delta^f_r(z)$ and a finite configuration of free
$\kappa[t^{-1}, t]$-modules
$\hat \delta^f_r$ of rank
$\delta^ f_r(z)$ indexed by the same numbers
$z$. This is in analogy with the configuration of eigenvalues and of generalized eigenspaces of a linear operator in a finite-dimensional complex vector space. The configuration
$\delta^f_r$ refines the Novikov–Betti number in dimension
$r$ and the configuration
$\hat \delta^f_r$ refines the Novikov homology in dimension
$r$ associated with the cohomology class defined by
$f$. In the case of the field
$\kappa= \mathbb C$, the configuration
$\hat \delta^f_r$ provides by “von-Neumann completion” of a configuration
$\hat{\hat \delta}^f_r$ of mutually orthogonal closed Hilbert submodules of the
$L_2$-homology of the infinite cyclic cover of
$X$ determined by the map
$f$, which is an
$L^\infty(\mathbb S^1)$-Hilbert module.
UDC:
515.142