Anti-Ramsey numbers for cancellative configurations in p-graphs

TL;DR

This paper investigates edge-colorings of complete p-graphs avoiding certain symmetric difference configurations, establishing bounds on the number of colors and characterizing extremal colorings, with implications for rainbow cancellative and Steiner triple systems.

Contribution

It generalizes a theorem of Erdős, Simonovits, and Sós to p-graphs, characterizes extremal colorings, and improves bounds related to rainbow F4-free colorings.

Findings

Maximum number of colors is at most 1 + floor(n/p) for p ≥ 3.

Constructs colorings with m(n)+1 colors for rainbow F4-free colorings, improving previous bounds.

Provides upper bounds on the number of colors for rainbow F4-free colorings, refining earlier quadratic bounds.

Abstract

We study edge-colorings of the complete $p$-graph on $n$ vertices that contain no three edges $A,B,C$ of distinct colors such that the symmetric difference of $A$ and $B$ is contained in $C$. For $p\ge3$ and $n\ge p+1$, we show that every such coloring contains at most $1+\floor{n/p}$ colors and characterize the extremal colorings, generalizing a theorem of Erd\H{o}s, Simonovits and S\'os. %\cite{erdos1975}. When $p=3$, the condition $A\triangle B\subseteq C$ implies $|A\triangle B|=2$, and the three edges necessarily form a copy of $F_4\coloneqq\{abc,abd,bcd\}$ or $F_5\coloneqq\{abc,abd,cde\}$. For $n\ge5$, we show that every rainbow $F_5$-free edge-coloring is rainbow cancellative. For rainbow $F_4$-free colorings, we construct colorings with $m(n)+1$ colors for all $n\ge4$, where $m(n)$ is the size of a maximum partial Steiner triple system of order $n$ and satisfies $m(n)=n^2/6+O(n)$, improving the linear lower bound by Budden and Stiles. %\cite{budden}. Moreover, for $n=2^s-1$, we obtain $\ar(n,F_4)\ge m(n)+n^2/42+o(n^2)=4n^2/21+o(n^2)$ via a construction based on independent sets in the Grassmann graph. We also prove that $\ar(n,F_4)\le (5n^2-8n)/21$ for $n\ge4$, improving the quadratic coefficient in the upper bound of Budden and Stiles from $1/4$ to $5/21$.