arXiv subjects

Karim Mansour

Publications and source records attributed to Karim Mansour.

5 recordsLinked to original sources

arXiv2025

A Deformation Theoretic Reduction of the Hodge Conjecture via Derived Categories and Complete Intersections

We propose a geometric and categorical approach to the Hodge Conjecture for all smooth projective complex varieties. By embedding any such variety into a flat family with general fibers smooth complete intersections, we prove the conjecture unconditionally in the complete intersection case using derived category methods. Through deformation arguments, we reduce the general case to the algebraicity of limits. While this remains an assumption, our framework unifies Hodge theory, deformation, and derived techniques, offering a concrete path toward resolving the conjecture.

math.AG↗

arXiv2025

A Conditional Reduction of the Rational Hodge Conjecture for Threefolds and Deformation-Theoretic Verifications in Several Families

We formulate a concrete geometric approximation hypothesis (Hypothesis~BB) asserting that codimension-$2$ Hodge classes on a smooth projective threefold can be realized as specializations of families whose general members are complete-intersection curves. We prove that Hypothesis~BB implies the (rational) Hodge conjecture for the threefold. We then give deformation-theoretic sufficient criteria (cohomology-vanishing and surjectivity conditions) which imply Hypothesis~BB, and we prove these criteria hold for the class of a line on a \emph{general} quintic threefold containing that line. We further formulate and prove several propositions showing that, under natural Noether--Lefschetz and unobstructedness hypotheses, Hypothesis~BB holds \emph{generically} in families of Calabi--Yau and Fano threefolds; these propositions reduce the problem to checkable conditions (normal-bundle cohomology, surjectivity of restriction maps). Finally, we include a Macaulay2 appendix with scripts to verify the required cohomology and splitting conditions in explicit examples.

math.AG↗

arXiv2025

A Perturbative Multiplicity Theorem for the Borsuk-Ulam Setting

We prove a generalization of the classical Borsuk--Ulam Theorem under small perturbations (shaking) of the sphere. We show that for a generic perturbation of a continuous map $f : S^2 \to \mathbb{R}^2$, the number of points $x \in S^2$ such that $f_ε(x) = f_ε(-x)$ becomes finite and odd, and may exceed the classical lower bound of one antipodal coincidence. In particular, we show the existence of maps with 3, 5, or 7 such points, and explain the unbounded nature of this multiplicity under higher complexity of the perturbation.

math.GM↗

arXiv2024

Indecomposable cycles and the case of the twisted Hodge D conjecture

We will introduce twisted cycles and their associated regulators to cohomology. We prove the conjecture that this regulator is surjective for a general smooth projective surface. We construct indecomposable twisted cycles on elliptic fourfolds, and use that to show that this map is non-zero.

math.AG↗

arXiv2021

The Hodge-D-Conjecture fora Product of Elliptic Curves

Let $X/C$ be a general product of elliptic curves. Our goal is to establish the Hodge-D-conjecture for $X$. We accomplish this when $\dim X \leq 5$. For $\dim X \geq 6$, we reduce the conjecture to a matrix rank condition that is amenable to computer calculation.

math.AG↗