TY - GEN
T1 - Task-structured probabilistic I/O automata
AU - Canetti, Ran
AU - Cheung, Ling
AU - Kaynar, Dilsun
AU - Liskov, Moses
AU - Lynch, Nancy
AU - Pereira, Olivier
AU - Segala, Roberto
PY - 2006
Y1 - 2006
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=34250771232&partnerID=8YFLogxK
U2 - 10.1109/WODES.2006.1678432
DO - 10.1109/WODES.2006.1678432
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AN - SCOPUS:34250771232
SN - 1424400538
SN - 9781424400539
T3 - Proceedings - Eighth International Workshop on Discrete Event Systems, WODES 2006
SP - 207
EP - 214
BT - Proceedings - Eighth International Workshop on Discrete Event Systems, WODES 2006
T2 - 8th International Workshop on Discrete Event Systems, WODES 2006
Y2 - 10 July 2006 through 12 July 2006
ER -