Outputs (16)

Surjective H-Colouring over reflexive digraphs (2018)
Journal Article
Larose, B., Martin, B., & Paulusma, D. (2018). Surjective H-Colouring over reflexive digraphs. ACM Transactions on Computation Theory, 11(1), Article 3. https://doi.org/10.1145/3282431

The Surjective H-Colouring problem is to test if a given graph allows a vertex-surjective homomorphism to a fixed graph H. The complexity of this problem has been well studied for undirected (partially) reflexive graphs. We introduce endo-triviality,... Read More about Surjective H-Colouring over reflexive digraphs.

Hereditary graph classes: when the complexities of coloring and clique cover coincide (2018)
Journal Article
Blanché, A., Dabrowski, K., Johnson, M., & Paulusma, D. (2019). Hereditary graph classes: when the complexities of coloring and clique cover coincide. Journal of Graph Theory, 91(3), 267-289. https://doi.org/10.1002/jgt.22431

graph is (H1;H2)-free for a pair of graphs H1;H2 if it contains no induced subgraph isomorphic to H1 or H2. In 2001, Král’, Kratochvíl, Tuza, and Woeginger initiated a study into the complexity of Colouring for (H1;H2)-free graphs. Since then, others... Read More about Hereditary graph classes: when the complexities of coloring and clique cover coincide.

On the parameterized complexity of (k,s)-SAT (2018)
Journal Article
Paulusma, D., & Szeider, S. (2019). On the parameterized complexity of (k,s)-SAT. Information Processing Letters, 43, 34-36. https://doi.org/10.1016/j.ipl.2018.11.005

Let (k, s)-SAT be the k-SAT problem restricted to formulas in which each variable occurs in at most s clauses. It is well known that (3, 3)-SAT is trivial and (3, 4)-SAT is NP-complete. Answering a question posed by Iwama and Takaki (DMTCS 1997), Ber... Read More about On the parameterized complexity of (k,s)-SAT.

Colouring (Pr+Ps)-free graphs (2018)
Presentation / Conference Contribution
Klimošová, T., Malík, J., Masařík, T., Novotná, J., Paulusma, D., & Slívová, V. (2018, December). Colouring (Pr+Ps)-free graphs. Presented at 29th International Symposium on Algorithms and Computation (ISAAC 2018)., Jiaoxi, Yilan County, Taiwan

The k-Colouring problem is to decide if the vertices of a graph can be coloured with at most k colours for a fixed integer k such that no two adjacent vertices are coloured alike. If each vertex u must be assigned a colour from a prescribed list L(u)... Read More about Colouring (Pr+Ps)-free graphs.

Critical vertices and edges in H-free graphs (2018)
Journal Article
Paulusma, D., Picouleau, C., & Ries, B. (2019). Critical vertices and edges in H-free graphs. Discrete Applied Mathematics, 257, 361-367. https://doi.org/10.1016/j.dam.2018.08.016

A vertex or edge in a graph is critical if its deletion reduces the chromatic number of the graph by one. We consider the problems of deciding whether a graph has a critical vertex or edge, respectively. We give a complexity dichotomy for both proble... Read More about Critical vertices and edges in H-free graphs.

Connected Vertex Cover for (sP1+P5)-free graphs (2018)
Presentation / Conference Contribution
Johnson, M., Paesani, G., & Paulusma, D. (2018, June). Connected Vertex Cover for (sP1+P5)-free graphs. Presented at 44th International Workshop on Graph-Theoretic Concepts in Computer Science (WG 2018)., Cottbus, Germany

The Connected Vertex Cover problem is to decide if a graph G has a vertex cover of size at most k that induces a connected subgraph of G. This is a well-studied problem, known to be NP-complete for restricted graph classes, and, in particular, for H-... Read More about Connected Vertex Cover for (sP1+P5)-free graphs.

Computing small pivot-minors (2018)
Presentation / Conference Contribution
Dabrowski, K. K., Dross, F., Jeong, J., Kanté, M. M., Kwon, O., Oum, S., & Paulusma, D. (2018, June). Computing small pivot-minors. Presented at 44th International Workshop on Graph-Theoretic Concepts in Computer Science (WG 2018)., Cottbus, Germany

A graph G contains a graph H as a pivot-minor if H can be obtained from G by applying a sequence of vertex deletions and edge pivots. Pivot-minors play an important role in the study of rank-width. However, so far, pivot-minors have only been studied... Read More about Computing small pivot-minors.

Simple games versus weighted voting games (2018)
Presentation / Conference Contribution
Hof, F., Kern, W., Kurz, S., & Paulusma, D. (2018, September). Simple games versus weighted voting games. Presented at 11th International Symposium on Algorithmic Game Theory (SAGT 2018)., Beijing, China

A simple game (N, v) is given by a set N of n players and a partition of 2N into a set L of losing coalitions L with value v(L)=0 that is closed under taking subsets and a set W of winning coalitions W with v(W)=1 . Simple games with α=minp≥0maxW∈W,L... Read More about Simple games versus weighted voting games.

Contraction and Deletion Blockers for Perfect Graphs and H -free Graphs (2018)
Journal Article
Diner, Ö., Paulusma, D., Picouleau, C., & Ries, B. (2018). Contraction and Deletion Blockers for Perfect Graphs and H -free Graphs. Theoretical Computer Science, 746, 49-72. https://doi.org/10.1016/j.tcs.2018.06.023

We study the following problem: for given integers d, k and graph G, can we reduce some fixed graph parameter π of G by at least d via at most k graph operations from some fixed set S? As parameters we take the chromatic number χ, clique number ω and... Read More about Contraction and Deletion Blockers for Perfect Graphs and H -free Graphs.

Independent Feedback Vertex Set for P5-free Graphs (2018)
Journal Article
Bonamy, M., Dabrowski, K., Feghali, C., Johnson, M., & Paulusma, D. (2018). Independent Feedback Vertex Set for P5-free Graphs. Algorithmica, 81(4), 1416-1449. https://doi.org/10.1007/s00453-018-0474-x

The NP-complete problem Feedback Vertex Set is that of deciding whether or not it is possible, for a given integer k≥0 , to delete at most k vertices from a given graph so that what remains is a forest. The variant in which the deleted vertices must... Read More about Independent Feedback Vertex Set for P5-free Graphs.