Outputs (671)

The complexity of computing optimum labelings for temporal connectivity (2022)
Presentation / Conference Contribution
Klobas, N., Mertzios, G., Molter, H., & Spirakis, P. (2022, August). The complexity of computing optimum labelings for temporal connectivity. Presented at 47th International Symposium on Mathematical Foundations of Computer Science (MFCS 2022), Vienna, Austria

A graph is temporally connected if there exists a strict temporal path, i.e., a path whose edges have strictly increasing labels, from every vertex u to every other vertex v. In this paper we study temporal design problems for undirected temporally c... Read More about The complexity of computing optimum labelings for temporal connectivity.

Bent functions in the partial spread class generated by linear recurring sequences (2022)
Journal Article
Gadouleau, M., Mariot, L., & Picek, S. (2023). Bent functions in the partial spread class generated by linear recurring sequences. Designs, Codes and Cryptography, 91(1), 63-82. https://doi.org/10.1007/s10623-022-01097-1

We present a construction of partial spread bent functions using subspaces generated by linear recurring sequences (LRS). We first show that the kernels of the linear mappings defined by two LRS have a trivial intersection if and only if their feedba... Read More about Bent functions in the partial spread class generated by linear recurring sequences.

Colouring generalized claw-free graphs and graphs of large girth: Bounding the diameter (2022)
Journal Article
Martin, B., Paulusma, D., & Smith, S. (2022). Colouring generalized claw-free graphs and graphs of large girth: Bounding the diameter. Theoretical Computer Science, 931, 104-116. https://doi.org/10.1016/j.tcs.2022.07.034

For a fixed integer, the k-Colouring problem is to decide if the vertices of a graph can be coloured with at most k colours for an integer k, such that no two adjacent vertices are coloured alike. A graph G is H-free if G does not contain H as an ind... Read More about Colouring generalized claw-free graphs and graphs of large girth: Bounding the diameter.

Evaluating Gaussian Grasp Maps for Generative Grasping Models (2022)
Presentation / Conference Contribution
Prew, W., Breckon, T., Bordewich, M., & Beierholm, U. (2022, July). Evaluating Gaussian Grasp Maps for Generative Grasping Models. Presented at Proc. Int. Joint Conf. Neural Networks, Padova, Italy

Generalising robotic grasping to previously unseen objects is a key task in general robotic manipulation. The current method for training many antipodal generative grasping models rely on a binary ground truth grasp map generated from the centre thir... Read More about Evaluating Gaussian Grasp Maps for Generative Grasping Models.

Partitioning H-free graphs of bounded diameter (2022)
Journal Article
Brause, C., Golovach, P., Martin, B., Paulusma, D., & Smith, S. (2022). Partitioning H-free graphs of bounded diameter. Theoretical Computer Science, 930, 37-52. https://doi.org/10.1016/j.tcs.2022.07.009

A natural way of increasing our understanding of NP-complete graph problems is to restrict the input to a special graph class. Classes of H-free graphs, that is, graphs that do not contain some graph H as an induced subgraph, have proven to be an ide... Read More about Partitioning H-free graphs of bounded diameter.

The complexity of temporal vertex cover in small-degree graphs (2022)
Presentation / Conference Contribution
Hamm, T., Klobas, N., Mertzios, G., & Spirakis, P. (2023, February). The complexity of temporal vertex cover in small-degree graphs. Presented at 36th AAAI Conference on Artificial Intelligence (AAAI 2022), Vancouver, BC

Temporal graphs naturally model graphs whose underlying topology changes over time. Recently, the problems Temporal Vertex Cover (or TVC) and Sliding-Window Temporal Vertex Cover (or ∆- TVC for time-windows of a fixed-length ∆) have been established... Read More about The complexity of temporal vertex cover in small-degree graphs.

Acyclic, Star, and Injective Colouring: Bounding the diameter (2022)
Journal Article
Brause, C., Golovach, P., Martin, B., Ochem, P., Paulusma, D., & Smith, S. (2022). Acyclic, Star, and Injective Colouring: Bounding the diameter. Electronic Journal of Combinatorics, 29(2), https://doi.org/10.37236/10738

We examine the effect of bounding the diameter for a number of natural and well-studied variants of the COLOURING problem. A colouring is acyclic, star, or injective if any two colour classes induce a forest, star forest or disjoint union of vertices... Read More about Acyclic, Star, and Injective Colouring: Bounding the diameter.

Computing Balanced Solutions for Large International Kidney Exchange Schemes (2022)
Presentation / Conference Contribution
Benedek, M., Biró, P., Kern, W., & Paulusma, D. (2022, May). Computing Balanced Solutions for Large International Kidney Exchange Schemes. Presented at AAMAS ' 22: International Conference on Autonomous Agents and Multi-Agent Systems, Virtual Event / New Zealand

To overcome incompatibility issues, kidney patients may swap their donors. In international kidney exchange programmes (IKEPs), countries merge their national patient–donor pools. We consider a recently introduced credit system. In each round, countr... Read More about Computing Balanced Solutions for Large International Kidney Exchange Schemes.

On the Complexity of Optimising Variants of Phylogenetic Diversity on Phylogenetic Networks (2022)
Journal Article
Bordewich, M., Semple, C., & Wicke, K. (2022). On the Complexity of Optimising Variants of Phylogenetic Diversity on Phylogenetic Networks. Theoretical Computer Science, 917, 66-80. https://doi.org/10.1016/j.tcs.2022.03.012

Phylogenetic Diversity (PD) is a prominent quantitative measure of the biodiversity of a collection of present-day species (taxa). This measure is based on the evolutionary distance among the species in the collection. Loosely speaking, if T is a roo... Read More about On the Complexity of Optimising Variants of Phylogenetic Diversity on Phylogenetic Networks.

Computing weighted subset odd cycle transversals in H-free graphs (2022)
Journal Article
Brettell, N., Johnson, M., & Paulusma, D. (2022). Computing weighted subset odd cycle transversals in H-free graphs. Journal of Computer and System Sciences, 128, 71-85. https://doi.org/10.1016/j.jcss.2022.03.002

For the Odd Cycle Transversal problem, the task is to find a small set S of vertices in a graph that intersects every cycle of odd length. The Subset Odd Cycle Transversal problem requires S to intersect only those odd cycles that include a vertex of... Read More about Computing weighted subset odd cycle transversals in H-free graphs.

QCSP on reflexive tournaments (2022)
Journal Article
Larose, B., Martin, B., Markovic, P., Paulusma, D., Smith, S., & Zivny, S. (2022). QCSP on reflexive tournaments. ACM Transactions on Computational Logic, 23(3), 1-22. https://doi.org/10.1145/3508069

We give a complexity dichotomy for the Quantified Constraint Satisfaction Problem QCSP(H) when H is a reflexive tournament. It is well known that reflexive tournaments can be split into a sequence of strongly connected components H1,…,Hn so that ther... Read More about QCSP on reflexive tournaments.

Colouring graphs of bounded diameter in the absence of small cycles (2022)
Journal Article
Martin, B., Paulusma, D., & Smith, S. (2022). Colouring graphs of bounded diameter in the absence of small cycles. Discrete Applied Mathematics, 314, 150-161. https://doi.org/10.1016/j.dam.2022.02.026

For k ≥ 1, a k-colouring c of G is a mapping from V (G) to {1, 2, . . . , k} such that c(u) 6= c(v) for any two adjacent vertices u and v. The k-Colouring problem is to decide if a graph G has a k-colouring. For a family of graphs H, a graph G is H-f... Read More about Colouring graphs of bounded diameter in the absence of small cycles.

The Complexity of L(p,q)-Edge-Labelling (2022)
Presentation / Conference Contribution
Berthe, G., Martin, B., Paulusma, D., & Smith, S. (2022, March). The Complexity of L(p,q)-Edge-Labelling. Presented at The 15th International Conference and Workshops on Algorithms and Computation (WALCOM 2021), University of Jember, East Java

The L(p, q)-Edge-Labelling problem is the edge variant of the well-known L(p, q)-Labelling problem. It is equivalent to the L(p, q)-Labelling problem itself if we restrict the input of the latter problem to line graphs. So far, the complexity of L(p,... Read More about The Complexity of L(p,q)-Edge-Labelling.

On the Maximum Agreement Subtree Conjecture for Balanced Trees (2022)
Journal Article
Bordewich, M., Linz, S., Owen, M., St. John, K., Semple, C., & Wicke, K. (2022). On the Maximum Agreement Subtree Conjecture for Balanced Trees. SIAM Journal on Discrete Mathematics, 36(1), 336-354. https://doi.org/10.1137/20m1379678

We give a counterexample to the conjecture of Martin and Thatte that two balanced rooted binary leaf-labelled trees on n leaves have a maximum agreement subtree (MAST) of size at least n 1 2 . In particular, we show that for any c > 0, there exist tw... Read More about On the Maximum Agreement Subtree Conjecture for Balanced Trees.

Interference-free walks in time: temporally disjoint paths (2021)
Presentation / Conference Contribution
Klobas, N., Mertzios, G., Molter, H., Niedermeier, R., & Zschoche, P. (2021, August). Interference-free walks in time: temporally disjoint paths. Presented at 30th International Joint Conference on Artificial Intelligence (IJCAI-21), Montreal, Quebec

We investigate the computational complexity of finding temporally disjoint paths or walks in temporal graphs. There, the edge set changes over discrete time steps and a temporal path (resp. walk) uses edges that appear at monotonically increasing tim... Read More about Interference-free walks in time: temporally disjoint paths.

Computing subset transversals in H-free graphs (2021)
Journal Article
Brettell, N., Johnson, M., Paesani, G., & Paulusma, D. (2022). Computing subset transversals in H-free graphs. Theoretical Computer Science, 902, 76-92. https://doi.org/10.1016/j.tcs.2021.12.010

we study the computational complexity of two well-known graph transversal problems, namely Subset Feedback Vertex Set and Subset Odd Cycle Transversal, by restricting the input to H-free graphs, that is, to graphs that do not contain some fixed graph... Read More about Computing subset transversals in H-free graphs.

Tree pivot-minors and linear rank-width (2021)
Journal Article
Dabrowski, K., Dross, F., Jeong, J., Kante, M., Kwon, O., Oum, S., & Paulusma, D. (2021). Tree pivot-minors and linear rank-width. SIAM Journal on Discrete Mathematics, 35(4), 2922-2945. https://doi.org/10.1137/21m1402339

Tree-width and its linear variant path-width play a central role for the graph minor relation. In particular, Robertson and Seymour (1983) proved that for every tree T, the class of graphs that do not contain T as a minor has bounded path-width. For... Read More about Tree pivot-minors and linear rank-width.

Partitioning H-free graphs of bounded diameter (2021)
Presentation / Conference Contribution
Brause, C., Golovach, P. A., Martin, B., Paulusma, D., & Smith, S. (2021, December). Partitioning H-free graphs of bounded diameter. Presented at 32nd International Symposium on Algorithms and Computation (ISAAC 2021), Fukuoka, Japan

A natural way of increasing our understanding of NP-complete graph problems is to restrict the input to a special graph class. Classes of H-free graphs, that is, graphs that do not contain some graph H as an induced subgraph, have proven to be an ide... Read More about Partitioning H-free graphs of bounded diameter.

The lattice and semigroup structure of multipermutations (2021)
Journal Article
Carvalho, C., & Martin, B. (2022). The lattice and semigroup structure of multipermutations. International Journal of Algebra and Computation, 32(2), 211-235. https://doi.org/10.1142/s0218196722500096

We study the algebraic properties of binary relations whose underlying digraph is smooth, that is, has no source or sink. Such objects have been studied as surjective hyper-operations (shops) on the corresponding vertex set, and as binary relations t... Read More about The lattice and semigroup structure of multipermutations.

Induced disjoint paths in AT-free graphs (2021)
Journal Article
Golovach, P., Paulusma, D., & van Leeuwen, E. (2022). Induced disjoint paths in AT-free graphs. Journal of Computer and System Sciences, 124, 170-191. https://doi.org/10.1016/j.jcss.2021.10.003

Paths P1, . . . , Pk in a graph G = (V, E) are mutually induced if any two distinct Pi and Pj have neither common vertices nor adjacent vertices (except perhaps their end-vertices). The Induced Disjoint Paths problem is to decide if a graph G with k... Read More about Induced disjoint paths in AT-free graphs.