Linear relations, monodromy and Jordan cells of a circle valued map
In this paper we consider the definition of " monodromy of an angle valued map" based on linear relations as proposed in Burghelea-Haller (3). This definition provides an alternative treatment of monodromy and computationally an alternative calculation of the "Jordan cells", topological persistence invariants of a circle valued maps introduced in Burghelea-Day (2). We give a new geometric proof that the monodromy is actually a homotopy invariant of a pair consisting of a compact ANR and an integral degree one cohomology class without any reference to the infinite cyclic cover associated to cohomology class as in (3), or to the graph representation associated an angle valued map defining the cohomology class as in (2). Most important, we describe an algorithm to calculate the monodromy for a simplicial angle valued map defined on a finite simplicial complex, providing a new algorithm for the calculation of the Jordan cells of the map, shorter than the one proposed in (2). We indicate the computational usefulness of "Jordan cells", and in particular of the proposed algorithm, for the calculation of other basic topological invariants of the pair.