Intuitively, a system simulates another system if is can match all of its moves.
The basic definition relates states within one transition system, but this is easily addapted to relate two separate transition systems by building a system consisting of the disjoint union of the corresponding components.
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2 Similarity of separate transition systems 3 See also |
Given a labelled state transition system (S, &Lambda, &rarr), a simulation relation is a binary relation R over S (i.e. R &sube S × S) such that for every pair of elements p, q &isin S, if (p,q)&isin R then for all &alpha &isin &Lambda, and for all p' &isin S,
Given two states p and q in S, p simulates q, written q &le p if there is a simulation R such that (q, p) &isin R. In such case p and q are said to be similar and &le is called the similarity relation.
The similarity relation &le is a preorder. Furthermore, it is the largest simulation relation over a given transition system.
When comparing two different transition systems (S', &Lambda', &rarr') and (S' ', &Lambda' ', &rarr' '), the basic notions of simulation and similarity can be used by forming the disjoint composition of the two machines, (S, &Lambda, &rarr) with S = S' &cup S' ', &Lambda = &Lambda' &cup &Lambda' ' and &rarr = &rarr' &cup &rarr' ', where &cup is the disjoint union operator between sets.
Formal definition
implies that there is a q' &isin S such that
and (p',q') &isin R.Similarity of separate transition systems
See also