A Lefschetz type result for Koszul cohomology

2004 ◽  
Vol 114 (4) ◽  
Author(s):  
Marian Aprodu ◽  
Jan Nagel
Keyword(s):  
Type Result ◽  
Lefschetz Type ◽  
Koszul Cohomology

scholarly journals A BARTH–LEFSCHETZ THEOREM FOR SUBMANIFOLDS OF A PRODUCT OF PROJECTIVE SPACES

2009 ◽  
Vol 20 (01) ◽  
pp. 77-96
Author(s):  
LUCIAN BĂDESCU ◽  
FLAVIA REPETTO
Keyword(s):  
Normal Bundle ◽  
Projective Spaces ◽  
Restriction Map ◽  
Vanishing Theorem ◽  
Type Result ◽  
Picard Groups ◽  
Lefschetz Type ◽  
Simply Connected ◽  
Join Construction ◽  
Torsion Free

Let X be a complex submanifold of dimension d of ℙm × ℙn (m ≥ n ≥ 2) and denote by α: Pic(ℙm × ℙn) → Pic(X) the restriction map of Picard groups, by NX|ℙm × ℙn the normal bundle of X in ℙm × ℙn. Set t := max{dim π1(X), dim π2(X)}, where π1 and π2 are the two projections of ℙm × ℙn. We prove a Barth–Lefschetz type result as follows: Theorem. If [Formula: see text] then X is algebraically simply connected, the map α is injective and Coker(α) is torsion-free. Moreover α is an isomorphism if [Formula: see text], or if [Formula: see text] and NX|ℙm×ℙn is decomposable. These bounds are optimal. The main technical ingredients in the proof are: the Kodaira–Le Potier vanishing theorem in the generalized form of Sommese ([18, 19]), the join construction and an algebraization result of Faltings concerning small codimensional subvarieties in ℙN (see [9]).

scholarly journals Approximation by a power series summability method of Kantorovich type Szász operators including Sheffer polynomials

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Valdete Loku ◽  
Naim L. Braha ◽  
Toufik Mansour ◽  
M. Mursaleen
Keyword(s):  
Power Series ◽  
Summability Method ◽  
Approximation Properties ◽  
Type Result ◽  
Szász Operators ◽  
Sheffer Polynomials

AbstractThe main purpose of this paper is to use a power series summability method to study some approximation properties of Kantorovich type Szász–Mirakyan operators including Sheffer polynomials. We also establish Voronovskaya type result.

Markovian random iterations of homeomorphisms of the circle

2021 ◽  
pp. 1-22
Author(s):  
EDGAR MATIAS
Keyword(s):  
Markov Chains ◽  
Invariance Principle ◽  
Exponential Synchronization ◽  
Type Result

Abstract In this paper we prove a local exponential synchronization for Markovian random iterations of homeomorphisms of the circle $S^{1}$ , providing a new result on stochastic circle dynamics even for $C^1$ -diffeomorphisms. This result is obtained by combining an invariance principle for stationary random iterations of homeomorphisms of the circle with a Krylov–Bogolyubov-type result for homogeneous Markov chains.

scholarly journals ON THE STABILITY OF SYZYGY BUNDLES

2011 ◽  
Vol 22 (04) ◽  
pp. 515-534 ◽  
Author(s):  
IUSTIN COANDĂ
Keyword(s):  
Projective Space ◽  
Complete Intersection ◽  
Vector Bundles ◽  
Elementary Proof ◽  
Base Point ◽  
Vector Spaces ◽  
Similar Argument ◽  
Vanishing Theorem ◽  
The Stability ◽  
Koszul Cohomology

We are concerned with the problem of the stability of the syzygy bundles associated to base-point-free vector spaces of forms of the same degree d on the projective space of dimension n. We deduce directly, from M. Green's vanishing theorem for Koszul cohomology, that any such bundle is stable if its rank is sufficiently high. With a similar argument, we prove the semistability of a certain syzygy bundle on a general complete intersection of hypersurfaces of degree d in the projective space. This answers a question of H. Flenner [Comment. Math. Helv.59 (1984) 635–650]. We then give an elementary proof of H. Brenner's criterion of stability for monomial syzygy bundles, avoiding the use of Klyachko's results on toric vector bundles. We finally prove the existence of stable syzygy bundles defined by monomials of the same degree d, of any possible rank, for n at least 3. This extends the similar result proved, for n = 2, by L. Costa, P. Macias Marques and R. M. Miro-Roig [J. Pure Appl. Algebra214 (2010) 1241–1262]. The extension to the case n at least 3 has been also, independently, obtained by P. Macias Marques in his thesis [arXiv:0909.4646/math.AG (2009)].

scholarly journals A new Gershgorin-type result for the localisation of the spectrum of matrices

2015 ◽  
Vol 288 (17-18) ◽  
pp. 1981-1994 ◽  
Author(s):  
Anna Dall'Acqua ◽  
Delio Mugnolo ◽  
Michael Schelling
Keyword(s):  
Type Result

scholarly journals A Brezis-Nirenberg type result for a nonlocal fractional operator

2016 ◽  
Vol 95 (1) ◽  
pp. 73-93 ◽  
Author(s):  
Jean Mawhin ◽  
Giovanni Molica Bisci
Keyword(s):  
Fractional Operator ◽  
Type Result

Positive Solutions for the Generalized Nonlinear Logistic Equations

2016 ◽  
Vol 59 (01) ◽  
pp. 73-86 ◽  
Author(s):  
Leszek Gasiński ◽  
Nikolaos S. Papageorgiou
Keyword(s):  
Differential Operator ◽  
Elliptic Equation ◽  
Positive Solutions ◽  
Type Result ◽  
Logistic Equations ◽  
Nonhomogeneous Differential Operator

AbstractWe consider a nonlinear parametric elliptic equation driven by a nonhomogeneous differential operator with a logistic reaction of the superdiòusive type. Using variationalmethods coupled with suitable truncation and comparison techniques, we prove a bifurcation type result describing the set of positive solutions as the parameter varies.

A Fan-type result on k-ordered graphs

2010 ◽  
Vol 110 (16) ◽  
pp. 651-654 ◽  
Author(s):  
Ruijuan Li
Keyword(s):  
Type Result ◽  
Ordered Graphs
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