Ida Kantor

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20232025

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3 papers · 1 filter

math.CO2025

Minimum blocking sets for families of partitions

Guillermo Gamboa Quintero, Ida Kantor

A $3$ -partition of an $n$ -element set $V$ is a triple of pairwise disjoint nonempty subsets $X, Y, Z$ such that $V = X \cup Y \cup Z$ . We determine the minimum size $φ_{3} (n)$ of a set $\m…

math.CO2024

Metric Spaces in Which Many Triangles Are Degenerate

Vašek Chvátal, Noé de Rancourt, Guillermo Gamboa Quintero +2

Richmond and Richmond (American Mathematical Monthly 104 (1997), 713--719) proved the following theorem: If, in a metric space with at least five points, all triangles are degenera…

math.CO2023

Sparse metric hypergraphs

Vašek Chvátal, Guillermo A. Gamboa Quintero., Ida Kantor

Given a metric space $(X, ρ)$ , we say $y$ is between $x$ and $z$ if $ρ (x, z) = ρ (x, y) + ρ (y, z)$ . A metric space gives rise to a 3-uniform hypergraph that has as hyperedges those tri…