Task-structured probabilistic I/O automata

Ran Canetti, Ling Cheung, Dilsun Kaynar, Moses Liskov, Nancy Lynch, Olivier Pereira, Roberto Segala

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Modeling frameworks such as Probabilistic I/O Automata (PIOA) and Markov Decision Processes permit both probabilistic and nondeterministic choices. In order to use such frameworks to express claims about probabilities of events, one needs mechanisms for resolving the nondeterministic choices. For PIOAs, nondeterministic choices have traditionally been resolved by schedulers that have perfect information about the past execution. However, such schedulers are too powerful for certain settings, such as cryptographic protocol analysis, where information must sometimes be hidden. Here, we propose a new, less powerful nondeterminismresolution mechanism for PIOAs, consisting of tasks and local schedulers. Tasks are equivalence classes of system actions that are scheduled by oblivious, global task sequences. Local schedulers resolve nondeterminism within system components, based on local information only. The resulting task-PIOA framework yields simple notions of external behavior and implementation, and supports simple compositionality results. We also define a new kind of simulation relation, and show it to be sound for proving implementation. We illustrate the potential of the task-PIOA framework by outlining its use in verifying an Oblivious Transfer protocol.

Original languageEnglish
Title of host publicationProceedings - Eighth International Workshop on Discrete Event Systems, WODES 2006
Number of pages8
StatePublished - 2006
Externally publishedYes
Event8th International Workshop on Discrete Event Systems, WODES 2006 - Ann Arbor, MI, United States
Duration: 10 Jul 200612 Jul 2006

Publication series

NameProceedings - Eighth International Workshop on Discrete Event Systems, WODES 2006


Conference8th International Workshop on Discrete Event Systems, WODES 2006
Country/TerritoryUnited States
CityAnn Arbor, MI


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