English

A simple solution to Ulam's liar game with one lie

Combinatorics 2007-05-23 v1

Abstract

Ulam asked for the maximum number of questions required to determine an integer between one and one million by asking questions whose answer is `Yes' or `No' and where one untruthful answer is allowed. Pelc showed that the number of questions required is 25. Here we give a simple proof of this result.

Cite

@article{arxiv.0705.1220,
  title  = {A simple solution to Ulam's liar game with one lie},
  author = {Deryk Osthus and Rachel Watkinson},
  journal= {arXiv preprint arXiv:0705.1220},
  year   = {2007}
}
R2 v1 2026-06-21T08:26:25.850Z