On intersection trajectories. [II.]

Intersection Homology II

In [19, 20] we introduced topological invariants IH~,(X) called intersection homology groups for the study of singular spaces X. These groups depend on the choice of a perversity p: a perversity is a function from {2, 3, ...} to the non-negative integers such that both /~(c) and c 2 / ~ ( c ) are positive and increasing functions of c (2.1). The group IHr is defined for spaces X called pseudoma...

Valuated Matroid Intersection II: Algorithms

Based on the optimality criteria established in Part I, we show a primal-type cyclecanceling algorithm and a primal-dual-type augmenting algorithm for the valuated independent assignment problem: Given a bipartite graph G = (V , V −;A) with arc weight w : A → R and matroid valuations ω and ω− on V + and V − respectively, find a matching M(⊆ A) that maximizes ∑ {w(a) | a ∈ M}+ ω(∂M) + ω−(∂−M), w...

Homotopical Intersection Theory, Ii: Equivariance

This paper is a sequel to [KW]. We develop here an intersection theory for manifolds equipped with an action of a finite group. As in [KW], our approach will be homotopy theoretic, enabling us to circumvent the specter of equivariant transversality. We give applications of our theory to embedding problems, equivariant fixed point problems and the study of periodic points of self maps.

Intersection-number Operators for Curves on Discs Ii

Let the braid group Bn act as (isotopy classes of) diffeomorphisms of an n-punctured disc Dn. Then there is an action of Bn on a polynomial algebra R = C [a1 , . . . , aN ] and a way of representing simple closed curves on Dn as elements of R. Fix k ∈ 2N. Using this approach we show that the image in Aut(R) of each Dehn twist τ about a simple closed γ in Dn satisfies a kind of characteristic eq...

Geometry on Nodal Curves Ii: Cycle Map and Intersection Calculus