 
Summary: Finitestate concurrent programs can be expressed
pairwise
Paul C. Attie
College of Computer Science,
Northeastern University,
Cullinane Hall,
360 Huntington Avenue, Boston, Massachusetts 02115.
attie@ccs.neu.edu
Abstract
We present a pairwise normal form for nitestate shared memory con
current programs: all variables are shared between exactly two processes,
and the guards on transitions are conjunctions of conditions over this
pairwise shared state. This representation has been used to eÆciently
(in polynomial time) synthesize and modelcheck correctness properties
of concurrent programs. Our main result is that any nite state concur
rent program can be transformed into pairwise normal form. Specically,
if Q is an arbitrary nitestate shared memory concurrent program, then
there exists a nitestate shared memory concurrent program P expressed
in pairwise normal form such that P is strongly bisimilar to Q. Our result
is constructive: we give an algorithm for producing P , given Q.
