Issues in Or-parallelism: Illustration

, p(X),

p(X) :- , X=a, , !,
p(X) :- , X=b,

main :- l, s.

:- parallel l/0.
l :- large_work_a.
l :- large_work_b.

:- parallel s/0.
s :- small_work_a.
s :- small_work_b.