scholarly journals K-Orbit Closures on G/B as Universal Degeneracy Loci for Flagged Vector Bundles with Symmetric or Skew-Symmetric Bilinear Form

2013 ◽  
Vol 18 (2) ◽  
pp. 557-594 ◽  
Author(s):  
Benjamin J. Wyser
Keyword(s):  
Bilinear Form ◽  
Vector Bundles ◽  
Symmetric Bilinear Form ◽  
Degeneracy Loci ◽  
Orbit Closures

scholarly journals Orbital Degeneracy Loci II: Gorenstein Orbits

2018 ◽  
Vol 2020 (24) ◽  
pp. 9887-9932 ◽  
Author(s):  
Vladimiro Benedetti ◽  
Sara Angela Filippini ◽  
Laurent Manivel ◽  
Fabio Tanturri
Keyword(s):  
Algebraic Group ◽  
Vector Bundles ◽  
Canonical Bundle ◽  
Coordinate Ring ◽  
Degeneracy Loci ◽  
Orbital Degeneracy ◽  
Orbit Closures ◽  
Low Dimensional

Abstract In [3] we introduced orbital degeneracy loci as generalizations of degeneracy loci of morphisms between vector bundles. Orbital degeneracy loci can be constructed from any stable subvariety of a representation of an algebraic group. In this paper we show that their canonical bundles can be conveniently controlled in the case where the affine coordinate ring of the subvariety is Gorenstein. We then study in a systematic way the subvarieties obtained as orbit closures in representations with finitely many orbits, and we determine the canonical bundles of the corresponding orbital degeneracy loci in the Gorenstein cases. Applications are given to the construction of low-dimensional varieties with negative or trivial canonical bundle.

scholarly journals Matroid connectivity and singularities of configuration hypersurfaces

2021 ◽  
Vol 111 (1) ◽  
Author(s):  
Graham Denham ◽  
Mathias Schulze ◽  
Uli Walther
Keyword(s):  
Bilinear Form ◽  
Symmetric Bilinear Form ◽  
Smooth Locus

AbstractConsider a linear realization of a matroid over a field. One associates with it a configuration polynomial and a symmetric bilinear form with linear homogeneous coefficients. The corresponding configuration hypersurface and its non-smooth locus support the respective first and second degeneracy scheme of the bilinear form. We show that these schemes are reduced and describe the effect of matroid connectivity: for (2-)connected matroids, the configuration hypersurface is integral, and the second degeneracy scheme is reduced Cohen–Macaulay of codimension 3. If the matroid is 3-connected, then also the second degeneracy scheme is integral. In the process, we describe the behavior of configuration polynomials, forms and schemes with respect to various matroid constructions.

scholarly journals Supervised learning using a symmetric bilinear form for record linkage

2015 ◽  
Vol 26 ◽  
pp. 144-153 ◽  
Author(s):  
Daniel Abril ◽  
Vicenç Torra ◽  
Guillermo Navarro-Arribas
Keyword(s):  
Supervised Learning ◽  
Bilinear Form ◽  
Record Linkage ◽  
Symmetric Bilinear Form

Maximal Sets of Pairwise Orthogonal Vectors in Finite Fields

2012 ◽  
Vol 55 (2) ◽  
pp. 418-423 ◽  
Author(s):  
Le Anh Vinh
Keyword(s):  
Positive Integer ◽  
Finite Field ◽  
Finite Fields ◽  
Bilinear Form ◽  
Symmetric Bilinear Form

AbstractGiven a positive integern, a finite fieldofqelements (qodd), and a non-degenerate symmetric bilinear formBon, we determine the largest possible cardinality of pairwiseB-orthogonal subsets, that is, for any two vectorsx,y∈ Ε, one hasB(x,y) = 0.

Trace Forms on Lie Algebras

1962 ◽  
Vol 14 ◽  
pp. 553-564 ◽  
Author(s):  
Richard Block
Keyword(s):  
Lie Algebra ◽  
Lie Algebras ◽  
Bilinear Form ◽  
Symmetric Bilinear Form ◽  
Trace Form ◽  
Finite Degree ◽  
Trace Forms ◽  
Matrix Products ◽  
The Matrix ◽  
Image Position

If L is a Lie algebra with a representation Δ a→aΔ (a in L) (of finite degree), then by the trace form f = fΔ of Δ is meant the symmetric bilinear form on L obtained by taking the trace of the matrix products:Then f is invariant, that is, f is symmetric and f(ab, c) — f(a, bc) for all a, b, c in L. By the Δ-radical L⊥ = L⊥ of L is meant the set of a in L such that f(a, b) = 0 for all b in L. Then L⊥ is an ideal and f induces a bilinear form , called a quotient trace form, on L/L⊥. Thus an algebra has a quotient trace form if and only if there exists a Lie algebra L with a representation Δ such that

scholarly journals On the realizable classes of the square root of the inverse different in the unitary class group

2017 ◽  
Vol 13 (04) ◽  
pp. 913-932 ◽  
Author(s):  
Sin Yi Cindy Tsang
Keyword(s):  
Abelian Group ◽  
Number Field ◽  
Bilinear Form ◽  
Class Group ◽  
Finite Abelian Group ◽  
Symmetric Bilinear Form ◽  
Square Root ◽  
Ring Of Integers ◽  
Trace Map ◽  
Odd Order

Let [Formula: see text] be a number field with ring of integers [Formula: see text] and let [Formula: see text] be a finite abelian group of odd order. Given a [Formula: see text]-Galois [Formula: see text]-algebra [Formula: see text], write [Formula: see text] for its trace map and [Formula: see text] for its square root of the inverse different, where [Formula: see text] exists by Hilbert’s formula since [Formula: see text] has odd order. The pair [Formula: see text] is locally [Formula: see text]-isometric to [Formula: see text] whenever [Formula: see text] is weakly ramified, in which case it defines a class in the unitary class group [Formula: see text] of [Formula: see text]. Here [Formula: see text] denotes the canonical symmetric bilinear form on [Formula: see text] defined by [Formula: see text] for all [Formula: see text]. We will study the set of all such classes and show that a subset of them forms a subgroup of [Formula: see text].

SINGULAR LOCI IN HOLOMORPHIC FAMILIES

1998 ◽  
Vol 09 (03) ◽  
pp. 277-293
Author(s):  
ADAM HARRIS
Keyword(s):  
Vector Bundles ◽  
A Priori ◽  
Complex Structure ◽  
Compact Complex Manifold ◽  
Entire Family ◽  
Analytic Subset ◽  
Degeneracy Loci ◽  
Singular Spaces ◽  
Singular Loci ◽  
Complex Projective

Let [Formula: see text] be a proper flat morphism between manifolds, and [Formula: see text] an analytic subset, such that the fibres Xt, for all [Formula: see text], determine a locally trivial deformation of a compact complex manifold. Non-generic fibres Xt, for t ∈ A, may be taken a priori to be singular spaces, or to have a smooth complex structure which is biholomorphically distinct from their generic neighbours. The main theorem of this article provides a sufficient condition for local triviality of the entire family [Formula: see text], in terms of the dimension of A and of the singular subvarieties of certain "degeneracy loci" in [Formula: see text]. Several specific applications of the main theorem are subsequently examined, some of which correspond sharply with examples of "structure-jumping" in complex deformations and "jumping loci" of vector bundles on complex projective space.

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