5,838 research outputs found
A wide-spectrum language for verification of programs on weak memory models
Modern processors deploy a variety of weak memory models, which for
efficiency reasons may (appear to) execute instructions in an order different
to that specified by the program text. The consequences of instruction
reordering can be complex and subtle, and can impact on ensuring correctness.
Previous work on the semantics of weak memory models has focussed on the
behaviour of assembler-level programs. In this paper we utilise that work to
extract some general principles underlying instruction reordering, and apply
those principles to a wide-spectrum language encompassing abstract data types
as well as low-level assembler code. The goal is to support reasoning about
implementations of data structures for modern processors with respect to an
abstract specification.
Specifically, we define an operational semantics, from which we derive some
properties of program refinement, and encode the semantics in the rewriting
engine Maude as a model-checking tool. The tool is used to validate the
semantics against the behaviour of a set of litmus tests (small assembler
programs) run on hardware, and also to model check implementations of data
structures from the literature against their abstract specifications
Soft Concurrent Constraint Programming
Soft constraints extend classical constraints to represent multiple
consistency levels, and thus provide a way to express preferences, fuzziness,
and uncertainty. While there are many soft constraint solving formalisms, even
distributed ones, by now there seems to be no concurrent programming framework
where soft constraints can be handled. In this paper we show how the classical
concurrent constraint (cc) programming framework can work with soft
constraints, and we also propose an extension of cc languages which can use
soft constraints to prune and direct the search for a solution. We believe that
this new programming paradigm, called soft cc (scc), can be also very useful in
many web-related scenarios. In fact, the language level allows web agents to
express their interaction and negotiation protocols, and also to post their
requests in terms of preferences, and the underlying soft constraint solver can
find an agreement among the agents even if their requests are incompatible.Comment: 25 pages, 4 figures, submitted to the ACM Transactions on
Computational Logic (TOCL), zipped file
Conformance Verification of Normative Specifications using C-O Diagrams
C-O Diagrams have been introduced as a means to have a visual representation
of normative texts and electronic contracts, where it is possible to represent
the obligations, permissions and prohibitions of the different signatories, as
well as what are the penalties in case of not fulfillment of their obligations
and prohibitions. In such diagrams we are also able to represent absolute and
relative timing constrains.
In this paper we consider a formal semantics for C-O Diagrams based on a
network of timed automata and we present several relations to check the
consistency of a contract in terms of realizability, to analyze whether an
implementation satisfies the requirements defined on its contract, and to
compare several implementations using the executed permissions as criteria.Comment: In Proceedings FLACOS 2012, arXiv:1209.169
Slot Games for Detecting Timing Leaks of Programs
In this paper we describe a method for verifying secure information flow of
programs, where apart from direct and indirect flows a secret information can
be leaked through covert timing channels. That is, no two computations of a
program that differ only on high-security inputs can be distinguished by
low-security outputs and timing differences. We attack this problem by using
slot-game semantics for a quantitative analysis of programs. We show how
slot-games model can be used for performing a precise security analysis of
programs, that takes into account both extensional and intensional properties
of programs. The practicality of this approach for automated verification is
also shown.Comment: In Proceedings GandALF 2013, arXiv:1307.416
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