scholarly journals Volume of line bundles via valuation vectors (different from Okounkov bodies)

2020 ◽  
Author(s):  
O Braunling
Keyword(s):  
Line Bundle ◽  
Convex Hull ◽  
Line Bundles ◽  
Volume Formula ◽  
Ample Cone ◽  
Big Line Bundle

Abstract Up to a factor 1/n!, the volume of a big line bundle agrees with the Euclidean volume of its Okounkov body. The latter is the convex hull of top rank valuation vectors of sections, all with respect to a single flag. In this paper, we give a new volume formula, valid in the ample cone. It is also based on top rank valuation vectors, but mixes data coming from several different flags.

The strength for line bundles

2021 ◽  
Vol 127 (3) ◽  
Author(s):  
Edoardo Ballico ◽  
Emanuele Ventura
Keyword(s):  
Line Bundle ◽  
Algebraic Variety ◽  
Commutative Algebra ◽  
Upper Bounds ◽  
Line Bundles ◽  
Homogeneous Polynomials

We introduce the strength for sections of a line bundle on an algebraic variety. This generalizes the strength of homogeneous polynomials that has been recently introduced to resolve Stillman's conjecture, an important problem in commutative algebra. We establish the first properties of this notion and give some tool to obtain upper bounds on the strength in this framework. Moreover, we show some results on the usual strength such as the reducibility of the set of strength two homogeneous polynomials.

scholarly journals Projective surfaces with K-very ample line bundles of degree ≤ 4K + 4

1994 ◽  
Vol 136 ◽  
pp. 57-79 ◽  
Author(s):  
Edoardo Ballico ◽  
Andrew J. Sommese
Keyword(s):  
Line Bundle ◽  
Projective Space ◽  
Smooth Surface ◽  
Negative Integer ◽  
Line Bundles ◽  
Restriction Map ◽  
Projective Surface ◽  
Projective Surfaces

A line bundle, L, on a smooth, connected projective surface, S, is defined [7] to be k-very ample for a non-negative integer, k, if given any 0-dimensional sub-scheme with length , it follows that the restriction map is onto. L is 1-very ample (respectively 0-very ample) if and only if L is very ample (respectively spanned at all points by global sections). For a smooth surface, S, embedded in projective space by | L | where L is very ample, L being k-very ample is equivalent to there being no k-secant Pk−1 to S containing ≥ k + 1 points of S.

scholarly journals Determinants, Pfaffians and Quasi-Free Representations of the CAR Algebra

1998 ◽  
Vol 10 (05) ◽  
pp. 705-721 ◽  
Author(s):  
Mauro Spera ◽  
Tilmann Wurzbacher
Keyword(s):  
Hilbert Space ◽  
Line Bundle ◽  
Line Bundles ◽  
Complex Structures ◽  
Square Root ◽  
Purification Procedure ◽  
Algebraic Construction ◽  
Infinite Dimensional ◽  
Weil Type ◽  
Determinant Line Bundle

In this paper we apply the theory of quasi-free states of CAR algebras and Bogolubov automorphisms to give an alternative C*-algebraic construction of the Determinant and Pfaffian line bundles discussed by Pressley and Segal and by Borthwick. The basic property of the Pfaffian of being the holomorphic square root of the Determinant line bundle (after restriction from the Hilbert space Grassmannian to the Siegel manifold, or isotropic Grassmannian, consisting of all complex structures on an associated Hilbert space) is derived from a Fock–anti-Fock correspondence and an application of the Powers–Størmer purification procedure. A Borel–Weil type description of the infinite dimensional Spin c- representation is obtained, via a Shale–Stinespring implementation of Bogolubov transformations.

scholarly journals Numerical dimension and a Kawamata–Viehweg–Nadel-type vanishing theorem on compact Kähler manifolds

2014 ◽  
Vol 150 (11) ◽  
pp. 1869-1902 ◽  
Author(s):  
Junyan Cao
Keyword(s):  
Line Bundle ◽  
Kähler Manifold ◽  
Kähler Manifolds ◽  
Line Bundles ◽  
Kahler Manifolds ◽  
Vanishing Theorem ◽  
Kahler Manifold ◽  
Singular Metrics ◽  
Compact Kähler Manifold

AbstractLet $X$ be a compact Kähler manifold and let $(L,{\it\varphi})$ be a pseudo-effective line bundle on $X$. We first define a notion of numerical dimension for pseudo-effective line bundles with singular metrics, and then discuss the properties of this numerical dimension. Finally, we prove a very general Kawamata–Viehweg–Nadel-type vanishing theorem on an arbitrary compact Kähler manifold.

SINGULAR CURVES WITH LINE BUNDLES L DEFINED OVER ${\mathbb F}_q$ AND WITH H0(L) = H1(L) = 0

2013 ◽  
Vol 06 (02) ◽  
pp. 1350023
Author(s):  
Edoardo Ballico
Keyword(s):  
Line Bundle ◽  
Line Bundles ◽  
Projective Curve ◽  
Similar Line

Here we prove the existence of several pairs (X, L), where X is a geometrically integral projective curve defined over 𝔽q and L is a line bundle on X defined over 𝔽q and with H0(X, L) = H1(X, L) = 0. These examples are obtained using the existence of similar line bundles on the normalization of X, i.e. a case studied by C. Ballet, C. Ritzenthaler and R. Roland.

scholarly journals The Morse inequalities for line bundles

1970 ◽  
Vol 11 (3) ◽  
pp. 260-264
Author(s):  
Samir Khabbaz
Keyword(s):  
Line Bundle ◽  
Critical Point ◽  
Critical Points ◽  
Differentiable Manifold ◽  
Line Bundles ◽  
Structural Group ◽  
Morse Inequalities ◽  
Degenerate Critical Point ◽  
Two Indices

In place of a real valued differentiable (C2) function on a closedn-dimensional differentiable manifoldM, we may more generally consider a differentiable section s in any line bundleLonM, assumed to have structural groupZ2, the group of integers modulo two. Since the usual definitions of a critical point and of a non-degenerate critical point are local in nature, and since composing a differentiable real valued function with the functiont→—t does not change its set of critical points or its set of non-degenerate critical point, it is clear that we may speak of critical points and nondegenerate critical points of the section s. Unless the bundle has a fixed trivialization however, the index of a non-degenerate critical point must be thought of as a set of two numbers {k, n—k), corresponding to the two indices arising from the two trivializations possible forLrestricted to a small enough neighborhood of the point, i.e. corresponding to the two possible ways of reading the index. With this understanding we extend the usual definitions, and call a differentiable (C2) section s of L a Morse section if each of its critical points is non-degenerate.

scholarly journals Explicit volume formula for a hyperbolic tetrahedron in terms of edge lengths

2021 ◽  
Author(s):  
Nikolay Abrosimov ◽  
Bao Vuong
Keyword(s):  
Convex Hull ◽  
Hyperbolic Space ◽  
General Type ◽  
Integral Formula ◽  
Sufficient Conditions ◽  
Gram Matrix ◽  
Dihedral Angles ◽  
Hyperbolic Tetrahedron ◽  
Volume Formula ◽  
Necessary And Sufficient

We consider a compact hyperbolic tetrahedron of a general type. It is a convex hull of four points called vertices in the hyperbolic space [Formula: see text]. It can be determined by the set of six edge lengths up to isometry. For further considerations, we use the notion of edge matrix of the tetrahedron formed by hyperbolic cosines of its edge lengths. We establish necessary and sufficient conditions for the existence of a tetrahedron in [Formula: see text]. Then we find relations between their dihedral angles and edge lengths in the form of a cosine rule. Finally, we obtain exact integral formula expressing the volume of a hyperbolic tetrahedron in terms of the edge lengths. The latter volume formula can be regarded as a new version of classical Sforza’s formula for the volume of a tetrahedron but in terms of the edge matrix instead of the Gram matrix.

scholarly journals Remarks on Determinant Line Bundles, Chern-Simons Forms and Invariants

2002 ◽  
Vol 91 (1) ◽  
pp. 5 ◽  
Author(s):  
Johan L. Dupont ◽  
Flemming Lindblad Johansen
Keyword(s):  
Line Bundle ◽  
Line Bundles ◽  
Manifolds With Boundary ◽  
Principal Bundles ◽  
Determinant Line Bundles ◽  
Chern Simons ◽  
Determinant Line Bundle

We study generalized determinant line bundles for families of principal bundles and connections. We explore the connections of this line bundle and give conditions for the uniqueness of such. Furthermore we construct for families of bundles and connections over manifolds with boundary, a generalized Chern-Simons invariant as a section of a determinant line bundle.

Approximable Algebras as Subalgebras of Section Rings

2020 ◽  
Author(s):  
Catriona Maclean
Keyword(s):  
Line Bundle ◽  
Projective Variety ◽  
Type Theorem ◽  
Graded Algebra ◽  
Graded Algebras ◽  
Graded Ring ◽  
Partial Converse ◽  
Big Line Bundle

Abstract In [2], Huayi Chen introduced approximable graded algebras, which he uses to prove a Fujita-type theorem in the arithmetic setting, and asked if any such algebra is the graded ring of a big line bundle on a projective variety. This was proved to be false in [ 8]. Continuing the analysis started in [8], we show that while not every approximable graded algebra is a sub algebra of the section ring of a big line bundle, we can associate to any approximable graded algebra $\textbf{B}$ a projective variety $X(\textbf{B})$ and an infinite divisor $D(\textbf{B}) =\sum _{i=1}^\infty a_i D_i$ with $a_i\rightarrow 0$ such that $\textbf{B}$ is a subalgebra of $$\begin{equation*} R( D(\textbf{B}))=\oplus_n H^0(X(\textbf{B}), n D(\textbf{B})).\end{equation*}$$We also establish a partial converse to these results by showing that if an infinite divisor $D=\sum _i a_iD_i$ converges in the space of numerical classes, then any full-dimensional sub-graded algebra of $\oplus _mH^0(X, \lfloor mD \rfloor ))$ is approximable.

scholarly journals On the growth of von Neumann dimension of harmonic spaces of semipositive line bundles over covering manifolds

2016 ◽  
Vol 27 (11) ◽  
pp. 1650093 ◽  
Author(s):  
Huan Wang
Keyword(s):  
Line Bundle ◽  
Main Tool ◽  
Line Bundles ◽  
Harmonic Space ◽  
Dolbeault Cohomology ◽  
Harmonic Forms ◽  
Von Neumann ◽  
Hermitian Manifolds ◽  
Von Neumann Dimension ◽  
Tensor Powers

We study the harmonic space of line bundle valued forms over a covering manifold with a discrete group action, and obtain an asymptotic estimate for the von Neumann dimension of the space of harmonic [Formula: see text]-forms with values in high tensor powers of a semipositive line bundle. In particular, we estimate the von Neumann dimension of the corresponding reduced [Formula: see text]-Dolbeault cohomology group. The main tool is a local estimate of the pointwise norm of harmonic forms with values in semipositive line bundles over Hermitian manifolds.

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