2,096 research outputs found
YAPA: A generic tool for computing intruder knowledge
Reasoning about the knowledge of an attacker is a necessary step in many
formal analyses of security protocols. In the framework of the applied pi
calculus, as in similar languages based on equational logics, knowledge is
typically expressed by two relations: deducibility and static equivalence.
Several decision procedures have been proposed for these relations under a
variety of equational theories. However, each theory has its particular
algorithm, and none has been implemented so far. We provide a generic procedure
for deducibility and static equivalence that takes as input any convergent
rewrite system. We show that our algorithm covers most of the existing decision
procedures for convergent theories. We also provide an efficient
implementation, and compare it briefly with the tools ProVerif and KiSs
Nothing new under the sun, or the moon, or both
PC and CR were supported by the PRIN grant 2010RP5RNM_001 from the Italian Ministry of University./nLB was supported by MINECO grant PSI2012-31961
A Weakest Pre-Expectation Semantics for Mixed-Sign Expectations
We present a weakest-precondition-style calculus for reasoning about the
expected values (pre-expectations) of \emph{mixed-sign unbounded} random
variables after execution of a probabilistic program. The semantics of a
while-loop is well-defined as the limit of iteratively applying a functional to
a zero-element just as in the traditional weakest pre-expectation calculus,
even though a standard least fixed point argument is not applicable in this
context. A striking feature of our semantics is that it is always well-defined,
even if the expected values do not exist. We show that the calculus is sound,
allows for compositional reasoning, and present an invariant-based approach for
reasoning about pre-expectations of loops
A probabilistic analysis of argument cogency
This paper offers a probabilistic treatment of the conditions for argument cogency as endorsed in informal logic: acceptability, relevance, and sufficiency. Treating a natural language argument as a reason-claim-complex, our analysis identifies content features of defeasible argument on which the RSA conditions depend, namely: change in the commitment to the reason, the reason’s sensitivity and selectivity to the claim, one’s prior commitment to the claim, and the contextually determined thresholds of acceptability for reasons and for claims. Results contrast with, and may indeed serve to correct, the informal understanding and applications of the RSA criteria concerning their conceptual dependence, their function as update-thresholds, and their status as obligatory rather than permissive norms, but also show how these formal and informal normative approachs can in fact align
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