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We study the Jordan normal forms of the local and global monodromies over complete intersection subvarieties of $C^n$ by using the theory of motivic Milnor fibers. The results will be explicitly described by the mixed volumes of the faces…

Algebraic Geometry · Mathematics 2018-01-31 Alexander Esterov , Kiyoshi Takeuchi

Let $X^{2n}\subseteq \mathbb{P} ^N$ be a smooth projective variety. Consider the intersection cohomology complex of the local system $R^{2n-1}\pi{_*}\mathbb{Q}$, where $\pi$ denotes the projection from the universal hyperplane family of…

Algebraic Geometry · Mathematics 2020-12-01 Vincenzo Di Gennaro , Davide Franco

Intersection cohomology is a way to enhance classical cohomology, allowing us to use a famous result called Poincar\'e duality on a large class of spaces known as stratified pseudomanifolds. There is a theoretically powerful way to arrive…

Algebraic Topology · Mathematics 2022-12-08 Sebastian Cea

We study the local and global intersection cohomology of the intersection of two Schubert varieties in a flag manifold. In this version some new references are added.

Algebraic Geometry · Mathematics 2023-07-25 M. Dyer , G. Lusztig

We prove a general formula for the intersection form of two arbitrary monomials in boundary divisors. Furthermore we present a tree basis of the cohomology of $\overline {M}_{0,n}$. With the help of the intersection form we determine the…

alg-geom · Mathematics 2008-02-03 Ralph Kaufmann

We explain intersection multiplicity defined by J. P. Serre, in terms of the Poincare product in Hodge theory by a modification of the chern character map. We also discuss a formulation of the Euler characteristic via the action of…

Algebraic Geometry · Mathematics 2019-07-18 Mohammad Reza Rahmati

We consider a hypersurface in $\mathbb{C}^n$ with an isolated singular point at the origin, and study the mixed Hodge structure of the stalk of its intersection cohomology complex at the origin. In particular we express the dimension of…

Algebraic Geometry · Mathematics 2017-02-13 Takahiro Saito

We show that intersection homology extends Poincare duality to manifold homotopically stratified spaces (satisfying mild restrictions). This includes showing that, on such spaces, the sheaf of singular intersection chains is…

Geometric Topology · Mathematics 2011-03-31 Greg Friedman

We extend the methods developed in our earlier work to algorithmically compute the intersection cohomology Betti numbers of reductive varieties. These form a class of highly symmetric varieties that includes equivariant compactifications of…

Algebraic Geometry · Mathematics 2007-05-23 Michel Brion , Roy Joshua

We show that the components, appearing in the decomposition theorem for contraction maps of torus actions of complexity one, are intersection cohomology complexes of even codimensional subvarieties. As a consequence, we obtain the vanishing…

Algebraic Geometry · Mathematics 2026-03-10 Marta Agustin Vicente , Narasimha Chary Bonala , Kevin Langlois

We continue our study of the variation of parabolic cohomology (math.AG/0310139) and derive an exact formula for the underlying Poincare duality. As an illustration of our methods, we compute the monodromy of the Picard-Euler system and its…

Algebraic Geometry · Mathematics 2007-05-23 Michael Dettweiler , Stefan Wewers

Using a cap product, we construct an explicit Poincar\'e duality isomorphism between the blown-up intersection cohomology and the Borel-Moore intersection homology, for any commutative ring of coefficients and second-countable, oriented…

Algebraic Topology · Mathematics 2020-09-22 Martintxo Saralegi-Aranguren , Daniel Tanré

Given a perversity function in the sense of intersection homology theory, the method of intersection spaces assigns to certain oriented stratified spaces cell complexes whose ordinary reduced homology with real coefficients satisfies…

Algebraic Topology · Mathematics 2019-10-23 Markus Banagl , Eugenie Hunsicker

We give a counterexample to a formula suggested by the work of Letellier and Rodriguez-Villegas (arXiv:2008.13435) for the mixed Poincar\'e series of character stacks for non-orientable surfaces. The counterexample is obtained by an…

Algebraic Geometry · Mathematics 2023-11-28 Tommaso Scognamiglio

For having a Poincar\'e duality via a cap product between the intersection homology of a paracompact oriented pseudomanifold and the cohomology given by the dual complex, G. Friedman and J. E. McClure need a coefficient field or an…

Algebraic Topology · Mathematics 2018-02-01 David Chataur , Martintxo Saralegi-Aranguren , Daniel Tanré

We present explicit formulas for the intersection pairing in the intersection cohomology of the moduli space $M_0(r)$ of rank-$r$, degree-$0$ semistable bundles on a Riemann surface. The key idea is to realize this intersection cohomology…

Algebraic Geometry · Mathematics 2026-03-03 Camilla Felisetti , Olga Trapeznikova

The theory of intersection spaces assigns cell complexes to certain stratified topological pseudomanifolds depending on a perversity function in the sense of intersection homology. The main property of the intersection spaces is Poincar\'e…

Algebraic Topology · Mathematics 2018-12-03 J. Timo Essig

We count points on character varieties associated with punctured surfaces and regular semisimple generic conjugacy classes in reductive groups. We find that the number of points are palindromic polynomials. This suggests a $P=W$ conjecture…

Algebraic Geometry · Mathematics 2026-01-23 Masoud Kamgarpour , GyeongHyeon Nam , Bailey Whitbread , Stefano Giannini

In this work, we study the intersection cohomology of Siegel modular varieties. The goal is to express the trace of a Hecke operator composed with a power of the Frobenius endomorphism (at a good place) on this cohomology in terms of the…

Representation Theory · Mathematics 2018-06-27 Sophie Morel

In the computation of the intersection cohomology of Shimura varieties, or of the $L^2$ cohomology of equal rank locally symmetric spaces, combinatorial identities involving averaged discrete series characters of real reductive groups play…

Combinatorics · Mathematics 2019-02-19 Richard Ehrenborg , Sophie Morel , Margaret Readdy