Choosing, Agreeing, and Eliminating in Communication Complexity

Amos Beimel, Sebastian Ben Daniel, Eyal Kushilevitz, Enav Weinreb

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


We consider several questions inspired by the direct-sum problem in (two-party) communication complexity. In all questions, there are k fixed Boolean functions f1,...,fk and each of Alice and Bob has k inputs, x1,...,xk and y1,...,yk, respectively. In the eliminate problem, Alice and Bob should output a vector σ1,...,σk such that fi(xi, yi) ≠ σi for at least one i (i.e., their goal is to eliminate one of the 2k output vectors); in the choose problem, Alice and Bob should return (i, fi(xi, yi)), for some i (i.e., they choose one instance to solve), and in the agree problem they should return fi(xi, yi), for some i (i.e., if all the k Boolean values agree then this must be the output). The question, in each of the three cases, is whether one can do better than solving one (say, the first) instance. We study these three problems and prove various positive and negative results. In particular, we prove that the randomized communication complexity of eliminate, of k instances of the same function f, is characterized by the randomized communication complexity of solving one instance of f.

Original languageEnglish
Pages (from-to)1-42
Number of pages42
JournalComputational Complexity
Issue number1
StatePublished - 1 Mar 2014


  • Communication complexity
  • direct sum
  • elimination
  • selection


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