Approximation, randomization, and combinatorial optimization. algorithms and techniques APPROX/RANDOM 2019, September 20–22, 2019, Massachusetts Institute of Technology, Cambridge, MA, USA - Achlioptas, Dimitris; Végh, László A. (Schloss Dagstuhl - Leibniz-Zentrum für Informatik GmbH, Dagstuhl Publishing, 2019)