English

Pseudodeterministic Communication Complexity

Computational Complexity 2025-11-10 v1

Abstract

We exhibit an nn-bit partial function with randomized communication complexity O(logn)O(\log n) but such that any completion of this function into a total one requires randomized communication complexity nΩ(1)n^{\Omega(1)}. In particular, this shows an exponential separation between randomized and \emph{pseudodeterministic} communication protocols. Previously, Gavinsky (2025) showed an analogous separation in the weaker model of parity decision trees. We use lifting techniques to extend his proof idea to communication complexity.

Keywords

Cite

@article{arxiv.2511.04794,
  title  = {Pseudodeterministic Communication Complexity},
  author = {Mika Göös and Nathaniel Harms and Artur Riazanov and Anastasia Sofronova and Dmitry Sokolov and Weiqiang Yuan},
  journal= {arXiv preprint arXiv:2511.04794},
  year   = {2025}
}