enrich
rtc-ref,
refset
with
functions reach : ref × (ref × ref → bool) → refset;
variables rrp : ref × ref → bool;
r : ref;
axioms
reachset : ⊦ r1 ∈ reach(r0, rrp) ↔ rrp ^*(r0, r1);
used for: s, ls;
end enrich