scholarly journals Hodge Theory of Cyclic Covers Branched over a Union of Hyperplanes

2014 ◽  
Vol 66 (3) ◽  
pp. 505-524 ◽  
Author(s):  
Donu Arapura
Keyword(s):  
Projective Space ◽  
Prime Number ◽  
Hyperplane Arrangement ◽  
Hodge Theory ◽  
Cyclic Cover ◽  
Hodge Conjecture ◽  
Cyclic Covers ◽  
Generalized Hodge Conjecture ◽  
Ramification Locus

AbstractSuppose that Y is a cyclic cover of projective space branched over a hyperplane arrangement D and that U is the complement of the ramification locus in Y. The first theorem in this paper implies that the Beilinson-Hodge conjecture holds for U if certain multiplicities of D are coprime to the degree of the cover. For instance, this applies when D is reduced with normal crossings. The second theorem shows that when D has normal crossings and the degree of the cover is a prime number, the generalized Hodge conjecture holds for any toroidal resolution of Y. The last section contains some partial extensions to more general nonabelian covers.

scholarly journals Simple cyclic covers of the plane and the Seshadri constants of some general hypersurfaces in weighted projective space

2021 ◽  
Author(s):  
Alex Küronya ◽  
Sönke Rollenske
Keyword(s):  
Projective Space ◽  
Irrational Number ◽  
Weighted Projective Space ◽  
Main Step ◽  
General Point ◽  
Cyclic Cover ◽  
Seshadri Constants ◽  
Cyclic Covers ◽  
Seshadri Constant

AbstractLet $$X \subset {\mathbb P}(1,1,1,m)$$ X ⊂ P ( 1 , 1 , 1 , m ) be a general hypersurface of degree md for some for $$d\ge 2$$ d ≥ 2 and $$m\ge 3$$ m ≥ 3 . We prove that the Seshadri constant $$\varepsilon ( {\mathcal O}_X(1), x)$$ ε ( O X ( 1 ) , x ) at a general point $$x\in X$$ x ∈ X lies in the interval $$\left[ \sqrt{d}- \frac{d}{m}, \sqrt{d}\right] $$ d - d m , d and thus approaches the possibly irrational number $$\sqrt{d}$$ d as m grows. The main step is a detailed study of the case where X is a simple cyclic cover of the plane.

Review of Hodge theory and algebraic cycles

2017 ◽  
Author(s):  
Claire Voisin
Keyword(s):  
Exact Sequence ◽  
Hodge Theory ◽  
Algebraic Cycles ◽  
Chow Groups ◽  
Hodge Conjecture ◽  
Hodge Structures ◽  
Mixed Hodge Structures ◽  
Generalized Hodge Conjecture ◽  
Cycle Classes

This chapter provides the background for the studies to be undertaken in succeeding chapters. It reviews Chow groups, correspondences and motives on the purely algebraic side, cycle classes, and (mixed) Hodge structures on the algebraic–topological side. Emphasis is placed on the notion of coniveau and the generalized Hodge conjecture which states the equality of geometric and Hodge coniveau. The chapter first follows the construction of Chow groups, the application of the localization exact sequence, the functoriality and motives of Chow groups, and cycle classes. It then turns to Hodge structures; pursuing related topics such as polarization, Hodge classes, standard conjectures, mixed Hodge structures, and Hodge coniveau.

scholarly journals Almost direct summands

2014 ◽  
Vol 214 ◽  
pp. 195-204 ◽  
Author(s):  
Bhargav Bhatt
Keyword(s):  
Direct Summand ◽  
Hodge Theory ◽  
Fundamental Theorems ◽  
Ramification Locus

AbstractWe prove new cases of the direct summand conjecture using fundamental theorems inp-adic Hodge theory due to Faltings. The cases tackled include the ones when the ramification locus lies entirely in characteristicp.

scholarly journals Moduli space holography and the finiteness of flux vacua

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Thomas W. Grimm
Keyword(s):  
Moduli Space ◽  
Moduli Spaces ◽  
Boundary Data ◽  
Hodge Theory ◽  
Two Dimensional ◽  
Hodge Conjecture ◽  
String Compactifications ◽  
Finiteness Result ◽  
Dimensional Gravity ◽  
Dimension One

Abstract A holographic perspective to study and characterize field spaces that arise in string compactifications is suggested. A concrete correspondence is developed by studying two-dimensional moduli spaces in supersymmetric string compactifications. It is proposed that there exist theories on the boundaries of each moduli space, whose crucial data are given by a Hilbert space, an Sl(2, ℂ)-algebra, and two special operators. This boundary data is motivated by asymptotic Hodge theory and the fact that the physical metric on the moduli space of Calabi-Yau manifolds asymptotes near any infinite distance boundary to a Poincaré metric with Sl(2, ℝ) isometry. The crucial part of the bulk theory on the moduli space is a sigma model for group-valued matter fields. It is discussed how this might be coupled to a two-dimensional gravity theory. The classical bulk-boundary matching is then given by the proof of the famous Sl(2) orbit theorem of Hodge theory, which is reformulated in a more physical language. Applying this correspondence to the flux landscape in Calabi-Yau fourfold compactifications it is shown that there are no infinite tails of self-dual flux vacua near any co-dimension one boundary. This finiteness result is a consequence of the constraints on the near boundary expansion of the bulk solutions that match to the boundary data. It is also pointed out that there is a striking connection of the finiteness result for supersymmetric flux vacua and the Hodge conjecture.

Knots which are branched cyclic covers of only finitely many knots

1985 ◽  
Vol 98 (2) ◽  
pp. 301-304
Author(s):  
Paul Strickland
Keyword(s):  
Cyclic Cover ◽  
Cyclic Covers ◽  
Infinite Cyclic Cover ◽  
Branched Cyclic Covers

In [5] we proved two results: theorem 1, which said that if k was a simple (2q – 1)-knot, q 1, then it was equivalent to the m-fold branched cyclic cover of another knot if and only if there existed an isometry u of its Blanchfield pairing 〈,〉, whose mth power was the map induced by a generator t of the group of covering translations associated with the infinite cyclic cover of k; and theorem 2, which showed that if k were the m-fold b.c.c. of two such knots, then these would be equivalent if and only if the corresponding isometries were conjugate by an isometry of 〈,〉. Using this second result, we present two cases where k may only be the m-fold b.c.c. of finitely many knots.

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