Grid designs

This paper investigates the existence of GG-designs (decompositions of complete graphs into edge-disjoint copies of a grid graph GG), proving that such designs exist for toroidal grids CnCnC_n \square C_n when nn is an odd prime or its square, and for the path-grid P4P4P_4 \square P_4 (which relates to scrambling Connections puzzles), while showing that P3P3P_3 \square P_3 admits no such design.

Alon Danai, Joshua Kou, Andy Latto, Haran Mouli, James ProppWed, 11 Ma🔢 math

On the Diameter of Arrangements of Topological Disks

This paper establishes that the diameter of the dual graph of an arrangement of nn topological disks is bounded by a function of nn and the maximum number of connected components in any pairwise intersection, providing a tight bound of max{2,2Δ}\max\{2, 2\Delta\} for two disks and an O(n32nΔ)O(n^3 2^n \Delta) bound for nn disks by analyzing the count of maximal faces.

Aida Abiad, Boris Aronov, Mark de Berg, Julian Golak, Alexander Grigoriev, Freija van LentWed, 11 Ma🔢 math

Ordinarization numbers of numerical semigroups

This paper investigates the enumeration of numerical semigroups of genus gg with a fixed ordinarization number rr by interpreting the problem as counting integer points in rational polyhedral cones using Ehrhart theory, while deriving specific formulas and geometric characterizations for cases involving ordinarization numbers 1 and 2, two-generated semigroups, supersymmetric semigroups, and interval-generated semigroups.

Sogol Cyrusian, Nathan KaplanWed, 11 Ma🔢 math

Some polynomial classes for the acyclic orientation with parity constraint problem

This paper identifies three necessary conditions for the existence of acyclic T-odd orientations, defines and characterizes polynomial graph classes where these conditions are sufficient, and provides constructive polynomial-time algorithms to build such orientations for these classes and their Cartesian products.

Sylvain Gravier (IF, SFR MAM), Matthieu Petiteau (IF, SFR MAM), Isabelle Sivignon (GIPSA-GAIA, SFR MAM)Wed, 11 Ma🔢 math