Coordinating swarms of objects at extreme dimensions -- A family of tree-based generators for bubbles in directed graphs -- The micro-world of cographs -- Parameterized Complexity of (A,`)-Path Packing -- On Proper Labellings of Graphs with Minimum Label Sum -- Decremental Optimization of Dominating Sets Under the Reconfiguration Framework -- On the Complexity of Stackelberg Matroid Pricing Problems -- Nonexistence Certificates for Ovals in a Projective Plane of Order Ten -- Edge-Disjoint Branchings in Temporal Graphs -- Optimal In-place Algorithms for Basic Graph Problems -- Further Results on Online Node- and Edge-Deletion Problems with Advice -- Fair packing of independent sets -- Polynomial Time Algorithms for Tracking Path Problems -- The SBP Algorithm for Maximizing Revenue in Online Dial-a-Ride -- Iterated Type Partitions -- Two Robots Patrolling on a Line: Integer Version and Approximability -- Ordering a Sparse Graph to Minimize the Sum of Right Ends of Edges -- On the Complexity of Singly Connected Vertex Deletion -- Equitable d-degenerate choosability of graphs -- On the complexity of Broadcast Domination and Multipacking in digraphs -- A Parameterized Perspective on Attacking and Defending Elections -- Skyline Computation with Noisy Comparisons -- Strongly Stable and Maximum Weakly Stable Noncrossing Matchings -- Connectivity Keeping Trees in 2-Connected Graphs with Girth Conditions -- The Steiner problem for count matroids -- Bounded Degree Group Steiner problems -- Between proper and strong edge-colorings of subcubic graphs -- Improved Budgeted Connected Domination and Budgeted Edge-Vertex Domination -- Algorithms for Constructing Anonymizing Arrays -- Parameterized algorithms for partial vertex covers in bipartite graphs -- Acyclic Matching in Some Subclasses of Graphs.

This book constitutes the proceedings of the 31st International Workshop on Combinatorial Algorithms which was planned to take place in Bordeaux, France, during June 8-10, 2020. Due to the COVID-19 pandemic the conference changed to a virtual format. The 30 full papers included in this book were carefully reviewed and selected from 62 submissions. They focus on algorithms design for the myriad of combinatorial problems that underlie computer applications in science, engineering and business.