Issue #7502 shows that running nlsat eagerly during final check can block quantifier instantiation.
To give space for quantifier instances we introduce two levels for final check such that nlsat is only applied in the second and final level.
Add API solve_for(vars).
It takes a list of variables and returns a triangular solved form for the variables.
Currently for arithmetic. The solved form is a list with elements of the form (var, term, guard).
Variables solved in the tail of the list do not occur before in the list.
For example it can return a solution [(x, z, True), (y, x + z, True)] because first x was solved to be z,
then y was solved to be x + z which is the same as 2z.
Add congruent_explain that retuns an explanation for congruent terms.
Terms congruent in the final state after calling SimpleSolver().check() can be queried for
an explanation, i.e., a list of literals that collectively entail the equality under congruence closure.
The literals are asserted in the final state of search.
Adjust smt_context cancellation for the smt.qi.max_instantiations parameter.
It gets checked when qi-queue elements are consumed.
Prior it was checked on insertion time, which didn't allow for processing as many
instantations as there were in the queue. Moreover, it would not cancel the solver.
So it would keep adding instantations to the queue when it was full / depleted the
configuration limit.
* remove inheritance from bound propagation
Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
* less inheritance
Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
* less inheritance
Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
* fix the build
Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
