01136647

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01136647 Kasangian, Stefano Vigna, Sebastiano The topos of labelled trees: A categorical semantics for SCCS. Ann. Soc. Math. Pol., Ser. IV, Fundam. Inf. 32, No.1, 27-45 (1997). 1997 IOS Press, Amsterdam EN semantics for SCCS Summary: We give a semantics for SCCS using the constructions of the topos of labelled trees. The semantics accounts for all aspects of the original formulation of SCCS, including unbounded non-determinism. Then, a partial solution to the problem of characterizing bisimulation in terms of a class of morphisms is proposed. We define a class of morphisms of the topos of trees, called conflict preserving, such that two trees $T$ and $U$ are bisimilar iff there is a pair of conflict preserving morphisms $f: T\to U$ and $g:U\to T$ such that $fgf= f$ and $gfg= g$. It is the first characterization which does not require the existence of a third quotient object. The results can be easily extended to more general transition systems.