• Mathematics of computing → Graph algorithms
  • Mathematics of computing → Random graphs
  • Mathematics of computing → Probabilistic algorithms
Michael Krivelevich
School of Mathematical Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
Tamás Mészáros
Fachbereich Mathematik und Informatik, Institut für Mathematik, Freie Universität Berlin, 14195 Berlin, Germany
Peleg Michaeli
School of Mathematical Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
Clara Shikhelman
Simons Institute for the Theory of Computing, Berkeley, CA, USA; School of Mathematical Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel

Abstract. The random greedy algorithm for finding a maximal independent set in a graph has been studied extensively in various settings in combinatorics, probability, computer science - and even in chemistry. The algorithm builds a maximal independent set by inspecting the vertices of the graph one at a time according to a random order, adding the current vertex to the independent set if it is not connected to any previously added vertex by an edge. In this paper we present a natural and general framework for calculating the asymptotics of the proportion of the yielded independent set for sequences of (possibly random) graphs, involving a useful notion of local convergence. We use this framework both to give short and simple proofs for results on previously studied families of graphs, such as paths and binomial random graphs, and to study new ones, such as random trees. We conclude our work by analysing the random greedy algorithm more closely when the base graph is a tree. We show that in expectation, the cardinality of a random greedy independent set in the path is no larger than that in any other tree of the same order.