Fields Notes 17:3 | Page 8

Life at Fields GROW: Workshop on Graph Classes, Optimization, and Width Parameters MANY PRACTICAL PROBLEMS in applied computer sci- ence can be modelled by a mathematical structure called a graph or network. Most of these problems, often expressed in an optimization framework – find the largest complete sub- graph, find the shortest spanning tour, find the minimum parti- tion into independent sets – are intractable in the sense that it is very unlikely that a polynomial time algorithm exists. A large fraction of theoretical computer science research deals with such complexity issues. Intractability properties such as NP-hardness necessitate novel theoretical and practical ad- vances – such as determining some underlying structure in the data – to find efficient, heuristic solutions to real world problems. The first GROW (Workshop on Graph Classes, Optimization, and Width Parameters) was held in Barcelona, Spain in 2001 as a conference of mathematicians and computer scientists engaged in cutting-edge research in the area of discrete optimization algorithms on graphs. At the second GROW in Prague, Czech Republic, in 2005, it was agreed that the workshop would become a biennial event. This year’s event was held at the Fields Institute in Toronto. A list of open problems presented at GROW 2017 is posted on the workshop website. As with other GROW workshops, GROW 2017 had both in- vited (Bruno Courcelle, Zdenek Dvorak, and Anna Lubiw) and contributed talks as well as problem solving or discussion sessions. Thus, the researchers had a forum to share and discuss interesting and important applications, problems, and solution methods, which inevitably resulted in the establish- ment of many new research collaborations. This is especially rewarding for young scientists. After each workshop, full versions of selected papers are in- vited to a special issue of the journal Discrete Applied Math- ematics. Andrzej Proskurowski will be the Editor in Chief of the DAM issue associated with GROW 2017. It has been an important tradition, and an indication of the interest among research groups in the themes of our workshops, that some open problems discussed during the workshop are often solved in subsequent special issues. GROW 2017 also greatly benefited from the serendipitous Tuesday, October 12th timing of Dr. Robert Tarjan's lecture on "Concurrent Disjoint Set Union" as part of U of T's Depart- ment of Computer Science Distinguished Lecture Series. From the beginning, GROW has been run as an academic, grass- roots directed event with no af- filiation with any formal organiza- tion. Furthermore, the workshop is invitation only with considerable emphasis spent on identifying new junior colleagues interested in the GROW areas. Through GROW, we hope to unite theory and practice by demonstrating how graph-theoretic concepts can be applied to various areas in computer science, and by extracting new application-motivat- ed problems.  — Derek G. Corneil 8