All Outputs (52)

On colouring (2P2,H)-free and (P5,H)-free graphs (2018)
Journal Article
Dabrowski, K., & Paulusma, D. (2018). On colouring (2P2,H)-free and (P5,H)-free graphs. Information Processing Letters, 134, 35-41. https://doi.org/10.1016/j.ipl.2018.02.003

The Colouring problem asks whether the vertices of a graph can be coloured with at most k colours for a given integer k in such a way that no two adjacent vertices receive the same colour. A graph is (H1,H2)-free if it has no induced subgraph isomorp... Read More about On colouring (2P2,H)-free and (P5,H)-free graphs.

On the price of independence for vertex cover, feedback vertex set and odd cycle transversal (2018)
Presentation / Conference Contribution
Dabrowski, K. K., Johnson, M., Paesani, G., Paulusma, D., & Zamaraev, V. (2018). On the price of independence for vertex cover, feedback vertex set and odd cycle transversal. In I. Potapov, P. Spirakis, & J. Worrell (Eds.), 43rd International Symposium on Mathematical Foundations of Computer Science (MFCS 2018) (63:1-63:15). https://doi.org/10.4230/lipics.mfcs.2018.63

Let vc(G), fvs(G) and oct(G) denote, respectively, the size of a minimum vertex cover, minimum feedback vertex set and minimum odd cycle transversal in a graph G. One can ask, when looking for these sets in a graph, how much bigger might they be if w... Read More about On the price of independence for vertex cover, feedback vertex set and odd cycle transversal.

Clique-Width for Graph Classes Closed under Complementation (2017)
Presentation / Conference Contribution
Blanché, A., Dabrowski, K. K., Johnson, M., Lozin, V. V., Paulusma, D., & Zamaraev, V. (2017). Clique-Width for Graph Classes Closed under Complementation. In K. G. Larsen, H. L. Bodlaender, & J. Raskin (Eds.), 42nd International Symposium on Mathematical Foundations of Computer Science (MFCS 2017) : August 21-25, 2017, Aalborg (Denmark) ; proceedings. https://doi.org/10.4230/lipics.mfcs.2017.73

Clique-width is an important graph parameter due to its algorithmic and structural properties. A graph class is hereditary if it can be characterized by a (not necessarily finite) set H of forbidden induced subgraphs. We initiate a systematic study i... Read More about Clique-Width for Graph Classes Closed under Complementation.

Independent feedback vertex sets for graphs of bounded diameter (2017)
Journal Article
Bonamy, M., Dabrowski, K., Feghali, C., Johnson, M., & Paulusma, D. (2018). Independent feedback vertex sets for graphs of bounded diameter. Information Processing Letters, 131, 26-32. https://doi.org/10.1016/j.ipl.2017.11.004

The Near-Bipartiteness problem is that of deciding whether or not the vertices of a graph can be partitioned into sets A and B, where A is an independent set and B induces a forest. The set A in such a partition is said to be an independent feedback... Read More about Independent feedback vertex sets for graphs of bounded diameter.

Clique-width and well-quasi ordering of triangle-free graph classes (2017)
Presentation / Conference Contribution
Dabrowski, K. K., Lozin, V. V., & Paulusma, D. (2017). Clique-width and well-quasi ordering of triangle-free graph classes. In H. L. Bodlaender, & G. J. Woeginger (Eds.), Graph-Theoretic Concepts in Computer Science : 43rd International Workshop, WG 2017, Eindhoven, The Netherlands, June 21-23, 2017. Revised selected papers (220-233). https://doi.org/10.1007/978-3-319-68705-6_17

Daligault, Rao and Thomassé asked whether every hereditary graph class that is well-quasi-ordered by the induced subgraph relation has bounded clique-width. Lozin, Razgon and Zamaraev (WG 2015) gave a negative answer to this question, but their count... Read More about Clique-width and well-quasi ordering of triangle-free graph classes.

Contracting bipartite graphs to paths and cycles (2017)
Presentation / Conference Contribution
Dabrowski, K., & Paulusma, D. (2017). Contracting bipartite graphs to paths and cycles. Electronic Notes in Discrete Mathematics, 61, 309-315. https://doi.org/10.1016/j.endm.2017.06.053

Testing if a given graph G contains the k-vertex path Pk as a minor or as an induced minor is trivial for every fixed integer k≥1. The situation changes for the problem of checking if a graph can be modified into Pk by using only edge contractions. I... Read More about Contracting bipartite graphs to paths and cycles.

Contracting Bipartite Graphs to Paths and Cycles (2017)
Journal Article
Dabrowski, K., & Paulusma, D. (2017). Contracting Bipartite Graphs to Paths and Cycles. Information Processing Letters, 127, 37-42. https://doi.org/10.1016/j.ipl.2017.06.013

Testing if a given graph G contains the k -vertex path Pk as a minor or as an induced minor is trivial for every fixed integer k≥1. However, the situation changes for the problem of checking if a graph can be modified into Pk by using only edge contr... Read More about Contracting Bipartite Graphs to Paths and Cycles.

Well-quasi-ordering versus clique-width: new results on bigenic classes (2017)
Journal Article
Dabrowski, K., Lozin, V., & Paulusma, D. (2018). Well-quasi-ordering versus clique-width: new results on bigenic classes. Order, 35(2), 253-274. https://doi.org/10.1007/s11083-017-9430-7

Daligault, Rao and Thomassé asked whether a hereditary class of graphs well-quasi-ordered by the induced subgraph relation has bounded clique-width. Lozin, Razgon and Zamaraev recently showed that this is not true for classes defined by infinitely ma... Read More about Well-quasi-ordering versus clique-width: new results on bigenic classes.

Recognizing Graphs Close to Bipartite Graphs (2017)
Presentation / Conference Contribution
Bonamy, M., Dabrowski, K. K., Feghali, C., Johnson, M., & Paulusma, D. (2017). Recognizing Graphs Close to Bipartite Graphs. In K. G. Larsen, H. L. Bodlaender, & J. Raskin (Eds.), 42nd International Symposium on Mathematical Foundations of Computer Science (MFCS 2017) : August 21-25, 2017, Aalborg (Denmark) ; proceedings. https://doi.org/10.4230/lipics.mfcs.2017.70

We continue research into a well-studied family of problems that ask if the vertices of a graph can be partitioned into sets A and B, where A is an independent set and B induces a graph from some specified graph class G. We let G be the class of k-de... Read More about Recognizing Graphs Close to Bipartite Graphs.

Colouring Diamond-free Graphs (2017)
Journal Article
Dabrowski, K., Dross, F., & Paulusma, D. (2017). Colouring Diamond-free Graphs. Journal of Computer and System Sciences, 89, 410-431. https://doi.org/10.1016/j.jcss.2017.06.005

The Colouring problem is that of deciding, given a graph G and an integer k, whether G admits a (proper) k-colouring. For all graphs H up to five vertices, we classify the computational complexity of Colouring for (diamond,H)-free graphs. Our proof i... Read More about Colouring Diamond-free Graphs.

Bounding the Clique-Width of H-free Chordal Graphs (2017)
Journal Article
Brandstädt, A., Dabrowski, K., Huang, S., & Paulusma, D. (2017). Bounding the Clique-Width of H-free Chordal Graphs. Journal of Graph Theory, 86(1), 42-77. https://doi.org/10.1002/jgt.22111

A graph is H-free if it has no induced subgraph isomorphic to H. Brandstädt, Engelfriet, Le, and Lozin proved that the class of chordal graphs with independence number at most 3 has unbounded clique-width. Brandstädt, Le, and Mosca erroneously claime... Read More about Bounding the Clique-Width of H-free Chordal Graphs.

Independent Feedback Vertex Set for P5-free Graphs (2017)
Presentation / Conference Contribution
Bonamy, M., Dabrowski, K. K., Feghali, C., Johnson, M., & Paulusma, D. (2017). Independent Feedback Vertex Set for P5-free Graphs. In Y. Okamoto, & T. Tokuyama (Eds.), 28th International Symposium on Algorithms and Computation (ISAAC 2017) ; proceedings (16:1-16:12). https://doi.org/10.4230/lipics.isaac.2017.16

The NP-complete problem Feedback Vertex Set is to decide if 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 form an independen... Read More about Independent Feedback Vertex Set for P5-free Graphs.

Editing to a Planar Graph of Given Degrees (2016)
Journal Article
Dabrowski, K., Golovach, P., van 't Hof, P., Paulusma, D., & Thilikos, D. (2016). Editing to a Planar Graph of Given Degrees. Journal of Computer and System Sciences, 85, 168-182. https://doi.org/10.1016/j.jcss.2016.11.009

We consider the following graph modification problem. Let the input consist of a graph G=(V,E), a weight function w:V∪E→N, a cost function c:V∪E→N0 and a degree function δ:V→N0, together with three integers kv,ke and C . The question is whether we ca... Read More about Editing to a Planar Graph of Given Degrees.

On the (Parameterized) Complexity of Recognizing Well-covered (r,l)-graphs (2016)
Presentation / Conference Contribution
Alves, S. R., Dabrowski, K. K., Faria, L., Klein, S., Sau, I., dos Santos Souza, U., …Wang, L. (2016). On the (Parameterized) Complexity of Recognizing Well-covered (r,l)-graphs. In Combinatorial optimization and applications : 10th International Conference, COCOA 2016, Hong Kong, China, December 16–18, 2016 ; proceedings (423-437). https://doi.org/10.1007/978-3-319-48749-6_31

An (r,ℓ)(r,ℓ)-partition of a graph G is a partition of its vertex set into r independent sets and ℓℓ cliques. A graph is (r,ℓ)(r,ℓ) if it admits an (r,ℓ)(r,ℓ)-partition. A graph is well-covered if every maximal independent set is also maximum. A grap... Read More about On the (Parameterized) Complexity of Recognizing Well-covered (r,l)-graphs.

Well-quasi-ordering versus clique-width: new results on bigenic classes (2016)
Presentation / Conference Contribution
Dabrowski, K. K., Lozin, V. V., & Paulusma, D. (2016). Well-quasi-ordering versus clique-width: new results on bigenic classes. In V. Mäkinen, S. J. Puglisi, & L. Salmela (Eds.), Combinatorial algorithms : 27th international workshop, IWOCA 2016, Helsinki, Finland, August 17-19, 2016 ; proceedings (253-265). https://doi.org/10.1007/978-3-319-44543-4_20

Daligault, Rao and Thomassé conjectured that if a hereditary class of graphs is well-quasi-ordered by the induced subgraph relation then it has bounded clique-width. Lozin, Razgon and Zamaraev recently showed that this conjecture is not true for infi... Read More about Well-quasi-ordering versus clique-width: new results on bigenic classes.

Bounding clique-width via perfect graphs (2016)
Journal Article
Dabrowski, K., Huang, S., & Paulusma, D. (2019). Bounding clique-width via perfect graphs. Journal of Computer and System Sciences, 104, 202-215. https://doi.org/10.1016/j.jcss.2016.06.007

We continue the study into the clique-width of graph classes defined by two forbidden induced graphs. We present three new classes of bounded clique-width and one of unbounded clique-width. The four new graph classes have in common that one of their... Read More about Bounding clique-width via perfect graphs.

Colouring diamond-free graphs (2016)
Presentation / Conference Contribution
Dabrowski, K. K., Dross, F., & Paulusma, D. (2016). Colouring diamond-free graphs. In R. Pagh (Ed.), 15th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT 2016). https://doi.org/10.4230/lipics.swat.2016.16

The Colouring problem is that of deciding, given a graph G and an integer k, whether G admits a (proper) k-colouring. For all graphs H up to five vertices, we classify the computational complexity of Colouring for (diamond,H)-free graphs. Our proof i... Read More about Colouring diamond-free graphs.

Bounding the clique-width of H-free split graphs (2016)
Journal Article
Brandstädt, A., Dabrowski, K., Huang, S., & Paulusma, D. (2016). Bounding the clique-width of H-free split graphs. Discrete Applied Mathematics, 211, 30-39. https://doi.org/10.1016/j.dam.2016.04.003

A graph is H-free if it has no induced subgraph isomorphic to H. We continue a study into the boundedness of clique-width of subclasses of perfect graphs. We identify five new classes of H-free split graphs whose clique-width is bounded. Our main res... Read More about Bounding the clique-width of H-free split graphs.

Filling the complexity gaps for colouring planar and bounded degree graphs (2016)
Presentation / Conference Contribution
Dabrowski, K. K., Dross, F., Johnson, M., & Paulusma, D. (2016). Filling the complexity gaps for colouring planar and bounded degree graphs. In Z. Lipták, & W. F. Smyth (Eds.), Combinatorial Algorithms : 26th International Workshop, Iwoca 2015, Verona, Italy, October 5-7, 2015, Revised selected papers (100-111). https://doi.org/10.1007/978-3-319-29516-9_9

We consider a natural restriction of the List Colouring problem, k-Regular List Colouring, which corresponds to the List Colouring problem where every list has size exactly k. We give a complete classification of the complexity of k-Regular List Colo... Read More about Filling the complexity gaps for colouring planar and bounded degree graphs.

Combinatorics and Algorithms for Augmenting Graphs (2015)
Journal Article
Dabrowski, K. K., Lozin, V. V., de Werra, D., & Zamaraev, V. (2016). Combinatorics and Algorithms for Augmenting Graphs. Graphs and Combinatorics, 32(4), 1339-1352. https://doi.org/10.1007/s00373-015-1660-0

The notion of augmenting graphs generalizes Berge’s idea of augmenting chains, which was used by Edmonds in his celebrated solution of the maximum matching problem. This problem is a special case of the more general maximum independent set (MIS) prob... Read More about Combinatorics and Algorithms for Augmenting Graphs.