The one-lie Rnyi-Ulam liar game is a two-player perfect information zero-sum game, lasting q rounds, on the set [n] {colon equals} {1, ..., n}. In each round Paul chooses a subset A [n] and Carole either assigns one lie to each element of A or to each element of [n] {set minus} A. Paul wins the original (resp. pathological) game if after q rounds there is at most one (resp. at least one) element with one or fewer lies. We exhibit a simple, unified, optimal strategy for Paul to follow in both games, and use this to determine which player can win for all q, n and for both games. 2007 Elsevier B.V. All rights reserved.
