Michael Lafferty

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math.CO2025

Connectivity of contraction-critical graphs

Michael Lafferty, Runrun Liu, Martin Rolek +1

Contraction-critical graphs came from the study of minimal counterexamples to Hadwiger's conjecture. A graph is $k$ -contraction-critical if it is $k$ -chromatic, but any proper mino…

math.CO2022

Every graph with no $K_{9}^{- 6}$ minor is $8$ -colorable

Michael Lafferty, Zi-Xia Song

For positive integers $t$ and $s$ , let $K_{t}^{- s}$ denote the family of graphs obtained from the complete graph $K_{t}$ by removing $s$ edges. A graph $G$ has no $\mathcal{K…

Connectivity of contraction-critical graphs

Every graph with no K9−6​ minor is 8-colorable

Every graph with no $K_{9}^{- 6}$ minor is $8$ -colorable