Lecture 5
7
Refinement checking and FDR
nLimits of trace semantics:
nIt is not compositional. Namely, trace refinement
nis not preserved under contexts.
nThis means that the analysis based on traces cannot
nbe performed modularly: it must be performed on
nthe whole system at once.
n
nExample   
nA = a -> (b -> Stop [] c -> Stop)
nB  =  a -> Stop [] a -> c -> Stop
n
a
c
b
a
a
b
c
Tr(A)  =
Tr(B)  =
{ a.b, a.c}
Context
C  =  a -> b  -> Stop
Tr(C || A)  =  {a.b}
                =/=
Tr(C || B)  =  {a.b , a}
A
B