Refinement checking and FDR

n Limits of trace semantics: It is not compositional. Namely, trace refinement is not preserved under contexts. This means that the analysis based on traces cannot be performed modularly: it must be performed on the whole system at once. n Example n A = a -> (b -> Stop [] c -> Stop) n B  =  a -> Stop [] a -> c -> Stop

A

B

Tr(A)  = Tr(B)  = { a.b, a.c}

a

a

a

c

b

b

c