Ulam's game

{{Short description|Mathematical guessing game}}

{{for|Ulam's topological game where players alternate choosing binary digits|binary game}}

Ulam's game, or the Rényi–Ulam game, is a mathematical game similar to the popular game of twenty questions. In Ulam's game, a player attempts to guess an unnamed object or number by asking yes–no questions of another, but one of the answers given may be a lie.{{cite web|title=How to Play Ulam's Game|url=http://math.iit.edu/~rellis/papers/9how.pdf|access-date=13 June 2013}}

{{harvs|txt|first=Alfréd|last=Rényi|authorlink=Alfréd Rényi|year=1961}} introduced the game in a 1961 paper, based on Hungary's Bar Kokhba game, but the paper was overlooked for many years.

Stanisław Ulam rediscovered the game, presenting the idea that there are a million objects and the answer to one question can be wrong, and considered the minimum number of questions required, and the strategy that should be adopted.{{sfnp|Ulam|1976|p=281}}{{cite arXiv |eprint=1609.07367|last1=Beluhov|first1=Nikolai |title=Renyi-Ulam Games and Forbidden Substrings|year=2016 |class=math.CO}} Pelc gave a survey of similar games and their relation to information theory.{{sfnp|Pelc|2002}}