Ingo Schiermeyer

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math.CO2024

On 3-colourability of $(b u l l, H)$ -free graphs

Nadzieja Hodur, Monika Pilśniak, Magdalena Prorok +1

The $3$ -colourability problem is a well-known NP-complete problem and it remains NP-complete for $b u l l$ -free graphs, where $b u l l$ is the graph consisting of $K_{3}$ with two pendant…

math.CO2024

Ramsey and Gallai-Ramsey numbers for linear forests and kipas

Ping Li, Yaping Mao, Ingo Schiermeyer +1

For two graphs $G, H$ , the \emph{Ramsey number} $r (G, H)$ is the minimum integer $n$ such that any red/blue edge-coloring of $K_{n}$ contains either a red copy of $G$ or a blue copy of…

On 3-colourability of (bull,H)-free graphs

Ramsey and Gallai-Ramsey numbers for linear forests and kipas

On 3-colourability of $(b u l l, H)$ -free graphs