


Lecture 5
Refinement checking and FDR
nWe want to define formally the notion of refinement wrt
trace semantics, in such a way that it captures the concept of “less
nondeterministic”.
nQuestion: what should be the formal definition of “A is a refinement of B” in terms of
their traces?
• Answer: Tr(A) is a subset of Tr(B)
B
A
Tr(A)