Improved Composition Theorems for Functions and Relations

Authors Sajin Koroth , Or Meir

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Author Details

Sajin Koroth
  • Department of Computer Science, University of Haifa, Haifa 3498838, Israel
Or Meir
  • Department of Computer Science, University of Haifa, Haifa 3498838,Israel

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Sajin Koroth and Or Meir. Improved Composition Theorems for Functions and Relations. In Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 116, pp. 48:1-48:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


One of the central problems in complexity theory is to prove super-logarithmic depth bounds for circuits computing a problem in P, i.e., to prove that P is not contained in NC^1. As an approach for this question, Karchmer, Raz and Wigderson [Mauricio Karchmer et al., 1995] proposed a conjecture called the KRW conjecture, which if true, would imply that P is not cotained in NC^{1}. Since proving this conjecture is currently considered an extremely difficult problem, previous works by Edmonds, Impagliazzo, Rudich and Sgall [Edmonds et al., 2001], Håstad and Wigderson [Johan Håstad and Avi Wigderson, 1990] and Gavinsky, Meir, Weinstein and Wigderson [Dmitry Gavinsky et al., 2014] considered weaker variants of the conjecture. In this work we significantly improve the parameters in these variants, achieving almost tight lower bounds.

Subject Classification

ACM Subject Classification
  • Theory of computation → Communication complexity
  • Theory of computation → Circuit complexity
  • Theory of computation → Complexity classes
  • circuit complexity
  • communication complexity
  • KRW conjecture
  • composition


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