deals with fluke regression for F* reported by Guido Martinez
Background:
The automatic pattern inference facility looks for terms that contains all bound variables of a quantifier. It may end up with a term that contains all bound variables but the extracted term can be simplified.
Example. The pattern
(ApplyTT (ApplyTT @x3!1 (ApplyTT @x4!0 (:var 1))) (ApplyTT @x4!0 (:var 0)))
can be decomposed into a multi-pattern
(ApplyTT @x4!0 (:var 1))) (ApplyTT @x4!0 (:var 0))
The multi-pattern may enable a quantifier instantiation while the original pattern does not. The multi-pattern should be preferred.
The regression showed up based on a change that should not be considered harmful but turned out to be noticeable.
The change was a simplification of and-or expressions based on sorting. This played with the case split queue used by F* (smt.case_split = 3) that uses a top-level case split of clauses to avoid redundant branches. The net effect was that without sorting, the benchmarks would always choose the opportune branch that enabled matching against the larger term. With sorting it would mostly choose inopportune branches.
- add option pp.no_lets (default = false) to print formulas without let (used by the low-level SMT2 printer).
- print lemmas2console faster by using the low level printer
- enforce elim-and in bool-rewriter when invoking hoisting.
- make cnf tactic more resilient to non-normalized input.
- enable eliminate predicates on ground formulas
- the literal false should not appear in clauses
- the literal true forces a tautology
- fix early return in is_cnf check. It should check all clauses for nested Booleans.
Add the ability to customize incremental pre-processing simplification for the SMTLIB2 front-end. The main new capability is to use pre-processing tactics in incremental mode that were previously not available. The main new capabilities are
- solve-eqs
- reduce-args
- elim-unconstrained
There are several more. Documentation and exposed simplifiers are populated incrementally. The current set of supported simplifiers can be inspected by using z3 with the --simplifiers flag or referring to https://microsoft.github.io/z3guide/docs/strategies/simplifiers
Some pending features are:
- add the ability to update parameters to simplifiers similar to how tactics can be controlled using parameters.
- expose simplification solvers over the binary API.
move sat_smt_preprocess to solver
fix bugs in model_reconstruction_trail for dependency replay
This is a preparatory step for exposing pre-processing as tactics.
