Karolina Okrasa

activity

20182026

most citedTuza's Conjecture for Threshold Graphs

2 citations · 3 across the 11 of their papers we have counts for

collaborators

Showing math.COShow all

6 papers · 1 filter

math.CO2024

Erdős-Pósa property of tripods in directed graphs

Marcin Briański, Meike Hatzel, Karolina Okrasa +1

Let $D$ be a directed graphs with distinguished sets of sources $S \subseteq V (D)$ and sinks $T \subseteq V (D)$ . A tripod in $D$ is a subgraph consisting of the union of two $S$ - $T$ -…

math.CO2024

Minimal obstructions to $C_{5}$ -coloring in hereditary graph classes

Jan Goedgebeur, Jorik Jooken, Karolina Okrasa +2

For graphs $G$ and $H$ , an $H$ -coloring of $G$ is an edge-preserving mapping from $V (G)$ to $V (H)$ . Note that if $H$ is the triangle, then $H$ -colorings are equivalent to $3$ -color…

math.CO2022

On digraphs without onion star immersions

Łukasz Bożyk, Oscar Defrain, Karolina Okrasa +1

The $t$ -onion star is the digraph obtained from a star with $2 t$ leaves by replacing every edge by a triple of arcs, where in $t$ triples we orient two arcs away from the center, a…

math.CO2022

Computing homomorphisms in hereditary graph classes: the peculiar case of the 5-wheel and graphs with no long claws

Michał Dębski, Zbigniew Lonc, Karolina Okrasa +2

For graphs $G$ and $H$ , an $H$ -coloring of $G$ is an edge-preserving mapping from $V (G)$ to $V (H)$ . In the $H$ -Coloring problem the graph $H$ is fixed and we ask whether an instanc…

math.CO2021★ 2 cited

Tuza's Conjecture for Threshold Graphs

Marthe Bonamy, Łukasz Bożyk, Andrzej Grzesik +4

Tuza famously conjectured in 1981 that in a graph without k+1 edge-disjoint triangles, it suffices to delete at most 2k edges to obtain a triangle-free graph. The conjecture holds…

math.CO2021

On objects dual to tree-cut decompositions