We propose a new framework for overcoming these obstacles, and provide the first definitions of computational solution concepts that guarantee sequential rationality. We argue that natural computational variants of subgame perfection are too strong for cryptographic protocols. As an alternative, we introduce a weakening called threat free Nash equilibrium that is more permissive but still eliminates the undesirable ``empty threats'' of non-sequential solution concepts.
To demonstrate the applicability of our framework, we revisit the problem of implementing a mediator for correlated equilibria (Dodis Halevi-Rabin, Crypto'00), and propose a variant of their protocol that is sequentially rational for a non-trivial class of correlated equilibria. Our treatment provides a better understanding of the conditions under which mediators in a correlated equilibrium can be replaced by a stable protocol.Category / Keywords: foundations / Date: received 18 Aug 2010 Contact author: alon rosen at idc ac il Available format(s): PDF | BibTeX Citation Version: 20100818:211031 (All versions of this report) Short URL: ia.cr/2010/448 Discussion forum: Show discussion | Start new discussion