Hans Hüttel

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Baeten, Bergstra, and Klop (and later Caucal) have proved the remarkable result that bisimulation equivalence is decidable for irredundant context-free grammars. In this paper we provide a much simpler and much more direct proof of this result using a tableau decision method involving goal-directed rules. The decision procedure also provides the essential(More)
Article history: Received 10 December 2007 Revised 18 November 2008 Available online 31 January 2009 The trace equivalence of BPP was shown to be undecidable by Hirshfeld. We show that all the preorders and equivalences except bisimulation in Glabbeek’s linear time-branching time spectrum are undecidable for BPP. The results are obtained by extending(More)
The spi-calculus, proposed by Abadi and Gordon, is a process calculus based on the π-calculus and is intended for reasoning about the behaviour of cryptographic protocols. We consider the finite-control fragment of the spi-calculus, showing it to be Turing-powerful (a result which is joint work with Josva Kleist, Uwe Nestmann, and Björn Victor.) Next, we(More)
Over the past decade much attention has been devoted to the study of process calculi such as CCS Mil80, Mil89], ACP BK84, BK88] and CSP Hoa88] as the foundations of a mathematical model for nondeterminism and concurrency. Of particular interest has been the study of the behavioural semantics of these calculi as given by transition graphs arising from(More)