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Positivity of Thom polynomials and Schubert calculus  [PDF]
Piotr Pragacz
Mathematics , 2013,
Abstract: We describe the positivity of Thom polynomials of singularities of maps, Lagrangian Thom polynomials and Legendrian Thom polynomials. We show that these positivities come from Schubert calculus.
Positivity of Schur function expansions of Thom polynomials  [PDF]
Piotr Pragacz,Andrzej Weber
Mathematics , 2006,
Abstract: Combining the Kazarian approach to Thom polynomials via classifying spaces of singularities with the Fulton-Lazarsfeld theory of numerical positivity for ample vector bundles, we show that the coefficients of various Schur function expansions of the Thom polynomials of stable and unstable singularities are nonnegative.
Thom polynomials of invariant cones, Schur functions, and positivity  [PDF]
Piotr Pragacz,Andrzej Weber
Mathematics , 2007,
Abstract: We generalize the notion of Thom polynomials from singularities of maps between two complex manifolds to invariant cones in representations, and collections of vector bundles. We prove that the generalized Thom polynomials, expanded in the products of Schur functions of the bundles, have nonnegative coefficients. For classical Thom polynomials associated with maps of complex manifolds, this gives an extension of our former result for stable singularities to nonnecessary stable ones. We also discuss some related aspects of Thom polynomials, which makes the article expository to some extent.
Positivity of Thom polynomials II: the Lagrange singularities  [PDF]
Malgorzata Mikosz,Piotr Pragacz,Andrzej Weber
Mathematics , 2007,
Abstract: We show that Thom polynomials of Lagrangian singularities have nonnegative coefficients in the basis consisting of Q-functions. The main tool in the proof is nonnegativity of cone classes for globally generated bundles.
Positivity of quiver coefficients through Thom polynomials  [PDF]
A. S. Buch,L. M. Feher,R. Rimanyi
Mathematics , 2003,
Abstract: Let r be an orbit of the quiver representation of type A_n (equioriented case). In this paper we study the Poincare dual of the closure of r (a.c.a. Thom polynomial/degeneracy loci formula) in equivariant cohomology. Using general Thom polynomial theory we prove the component formula and its stable version of [Knutson-Miller-Shimozono] as well as the positivity of the quiver coefficients of [Buch-Fulton]. We also show how the component formula follows from Grobner degeneration easily. In relation with the K-theory counterpart of the formula we give a new description of KMS factorizations based on transformations of lace diagrams.
On the structure of Thom polynomials of singularities  [PDF]
L. M. Feher,R. Rimanyi
Mathematics , 2007,
Abstract: Thom polynomials of singularities express the cohomology classes dual to singularity submanifolds. A stabilization property of Thom polynomials is known classically, namely that trivial unfolding does not change the Thom polynomial. In this paper we show that this is a special case of a product rule. The product rule enables us to calculate the Thom polynomials of singularities if we know the Thom polynomial of the product singularity. As a special case of the product rule we define a formal power series (Thom series, Ts_Q) associated with a commutative, complex, finite dimensional local algebra Q, such that the Thom polynomial of {\em every} singularity with local algebra Q can be recovered from Ts_Q.
Thom polynomials of Morin singularities  [PDF]
Gergely Berczi,Andras Szenes
Mathematics , 2006,
Abstract: We prove a formula for Thom polynomials of Morin (or A_d) singularities in any codimension. We use a combination of the test-curve method of Porteous, and the localization methods in equivariant cohomology. Our formulas are independent of the codimension, and they are computationally efficient for d less than 7.
On Schur function expansions of Thom polynomials  [PDF]
?zer ?ztürk,Piotr Pragacz
Mathematics , 2011,
Abstract: We discuss computations of the Thom polynomials of singularity classes of maps in the basis of Schur functions. We survey the known results about the bound on the length and a rectangle containment for partitions appearing in such Schur function expansions. We describe several recursions for the coefficients. For some singularities, we give old and new computations of their Thom polynomials.
Thom polynomials and Schur functions I  [PDF]
Piotr Pragacz
Mathematics , 2005,
Abstract: We give the Thom polynomials for the singularities I_2,2 and A_3 associated with maps (C^n,0) -> (C^{n+k},0) with parameter k>=0. We give the Schur function expansions of these Thom polynomials. Moreover, for the singularities A_i (with any parameter k >= 0) we analyze the ``first approximation'' F^(i) to the Thom polynomial. Our computations combine the characterization of Thom polynomials via the ``method of restriction equations'' of Rimanyi et al. with the techniques of (super) Schur functions.
Cobordism realizations of Thom polynomials of singularities  [PDF]
Andrei Kustarev
Mathematics , 2007,
Abstract: We define complex cobordism realizations of cohomological Thom polynomials and study their existence, uniqueness and other features. We show that problem is non-trivial on the example of $\Sigma^1$ singularity.
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