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From the 1 of 6 linked papers with an AI index.

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6 papers

math.CO2026

An improved polynomial -bound for -free graphs

Kaiyang Lan, Wenlong Zhong

Nguyen~\cite{Nguyen2025} recently proved that every -free graph satisfies . Building on his framework, we introduce two refinements, namely a s…

math.CO2026

The optimal -bound for -free graphs

Yidong Zhou, Kaiyang Lan

The paper proves that any graph that does not contain an induced path on six vertices, a dart, or a K4 as an induced subgraph can be colored with at most six colors, improving the…

math.CO2026

On a problem of Sivaraman and a problem of Gyárfás

Kaiyang Lan, Wenlong Zhong

The \textit{girth} of a graph , denoted , is the length of a shortest cycle in . If contains no cycle, we define . Sivaraman (2020) a…

math.CO2026

A non-hereditary Pollyanna class that is not strongly Pollyanna

Hongzhang Chen, Kaiyang Lan

Chudnovsky, Cook, Davies, and Oum introduced the notion of Pollyanna graph classes: a class is Pollyanna if for every -bounded class , the intersecti…

math.CO2026

On two conjectures of Hoà ng

Hongzhang Chen, Kaiyang Lan, Wenlong Zhong

A graph is said to be perfectly divisible if for every induced subgraph of with at least one edge, the vertex set can be partitioned into two sets such th…

math.CO2025

Trisimplicial vertices in (fork, odd parachute)-free graphs

Kaiyang Lan, Feng Liu, Di Wu +1

An {\em odd hole} in a graph is an induced subgraph which is a cycle of odd length at least five. An {\em odd parachute} is a graph obtained from an odd hole by adding a new ed…