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A simple efficiency preorder for CCS processes is introduced in whichp≲q means thatq is at least as fast asp, or more generally,p uses at least as much resources asq. It is shown to be preserved by all CCS contexts except summation and it is used to analyse a non-trivial example: two different implementations of a bounded buffer. Finally we give a sound and(More)
Model checking timed automata becomes increasingly complex with the increase in the number of clocks. Hence it is desirable that one constructs an automaton with the minimum number of clocks possible. The problem of checking whether there exists a timed automaton with a smaller number of clocks such that the timed language accepted by the original automaton(More)
We introduce a quantitative concept for bisimulations by integrating the notion of amortisation (cf. [3]). This allows us to make behavioural comparisons between nondeterministic systems that are inherently non-terminating and to analyse the relative long-term costs of deploying them. To this end, we conservatively extend CCS to include a new set of(More)
Return address corruption on the stack using buffer overflow attacks is one of the most common ways in which the security of a system can be compromised. This paper provides a way of detecting return address corruption on the stack using dynamic code instrumentation. The detection is done at run-time and it does not depend on the availability of source code(More)
  • S. Arun-Kumar
  • 2006
In this paper, we give a straightforward generalization of bisimulations to "bisimulations induced by a pair of relations" on the underlying action set. We establish that many of the nice properties of bisimulations and bisimilarities may be thought of as actually being inherited from properties of the underlying relations on actions. We show that many(More)
In this paper, we propose an at least as fast as relation between two timed automata states and investigate its decidability. The proposed relation is a prebisimulation and we show that given two processes with rational clock valuations it is decidable to check whether such a prebisimulation relation exists between them. Though bisimulation relations have(More)