This update includes an experimental feature to access a congruence closure data-structure after search.
It comes with several caveats as pre-processing is free to eliminate terms. It is therefore necessary to use a solver that does not eliminate the terms you want to track for congruence of. This is partially addressed by using SimpleSolver or incremental mode solving.
```python
from z3 import *
s = SimpleSolver()
x, y, z = Ints('x y z')
s.add(x == y)
s.add(y == z)
s.check()
print(s.root(x), s.root(y), s.root(z))
print(s.next(x), s.next(y), s.next(z))
```
This would crash before:
(declare-fun x () (_ BitVec 4))
(assert (not (bvule x #x1)))
(apply elim-uncnstr2)
That's because the index_set iterator was querying qtail to compute the end of the iteration
But the problem is that elim-uncnstr2 may add new fmls to the goal, as in this case.
The bvule is replaced with an 'or', but since it's negated, it turns into 2 goals
Solve the issue by freezing the qtail for the iteration loop.
This is the right behavior for elim-uncnstr2, as it can't rewrite exprs that haven't been analyzed before
@NikolajBjorner please check if this the right behavior for the other simplifiers. Thank you
- enable sat.smt in smt_tactic that
is invoked by default on first goals
add flatten-clauses
add push-ite
have tptp5 front-end pretty print SMT2 formulas a little nicer.
rename size() to qtail() and introduce shortcuts
ensure tactic goals are not updated if they are in inconsistent state (because indices could be invalidated)
- add sat.smt option to enable the new incremental core (it is not ready for mainstream consumption as cloning and other features are not implemented and it hasn't been tested in any detail yet).
- move "name" into attribute on simplifier so it can be reused for diagnostics by the seq-simplifier.
other updates:
- change signature of advance_qhead to simplify call sites
- have model reconstruction replay work on a tail of dependent_expr state, while adding formulas to the tail.
