Transition : computation step; rewriting using user predicates
if
, and and have the same predicate
symbol, or
if there is no rule
of such that and have the
same predicate symbol ( is a set of argument-wise equations)
if is a predicate symbol selected by the computation rule
Transition : selects constraints
if is a constraint selected by the computation rule
Transition : infers new constraints
In particular, may turn passive constraints into active ones