crash due to not checking for dead rows.
non-termination due to solving div and mod separately.
To ensure termination one needs to at least process them simultaneously, otherwise the metric of number-of-terms x under number of mod/div does not decrease. Substituting in K*y + z under either a mod or div increases the number of terms under a mod/div when eliminating only one of the kinds.
Currently handling divides constraints separately because pre-existing solution uses the model to determine z as a constant between 0 and K-1. The treatment of mod/div is supposed to be more general and use a variable while at the same time reducing the mod/div terms where the eliminated variable is used (the variable z is not added under the mod/div terms, but instead the model is used to determine cut-offs to calculate mod/div directly.
The existing comment describes macros as "formulas of the form
`(forall X (= (f X) T[X]))` ... where `T[X]` does not contain `X`". This is
incorrect; of course the macros' definitions are allowed to be in terms of
the macros' arguments. The comment should say "...does not contain `f`" because
macros can't be recursive.
This commit overhauls the proof format (in development) for the new core.
NOTE: this functionality is work in progress with a long way to go.
It is shielded by the sat.euf option, which is off by default and in pre-release state.
It is too early to fuzz or use it. It is pushed into master to shed light on road-map for certifying inferences of sat.euf.
It retires the ad-hoc extension of DRUP used by the SAT solver.
Instead it relies on SMT with ad-hoc extensions for proof terms.
It adds the following commands (consumed by proof_cmds.cpp):
- assume - for input clauses
- learn - when a clause is learned (or redundant clause is added)
- del - when a clause is deleted.
The commands take a list of expressions of type Bool and the
last argument can optionally be of type Proof.
When the last argument is of type Proof it is provided as a hint
to justify the learned clause.
Proof hints can be checked using a self-contained proof
checker. The sat/smt/euf_proof_checker.h class provides
a plugin dispatcher for checkers.
It is instantiated with a checker for arithmetic lemmas,
so far for Farkas proofs.
Use example:
```
(set-option :sat.euf true)
(set-option :tactic.default_tactic smt)
(set-option :sat.smt.proof f.proof)
(declare-const x Int)
(declare-const y Int)
(declare-const z Int)
(declare-const u Int)
(assert (< x y))
(assert (< y z))
(assert (< z x))
(check-sat)
```
Run z3 on a file with above content.
Then run z3 on f.proof
```
(verified-smt)
(verified-smt)
(verified-smt)
(verified-farkas)
(verified-smt)
```
a recent opened and closed bug report was due to an error of taking bit-wise or between two bit-vectors of different size. The error message was not understood by the user. Adding a little extra generic information to see if it helps.
this update addresses some perf regressions introduced when handling axioms for bv2int and a memory smash regression when decoupling bv-ackerman from in-processing. It adds a filter based on bv_eq_axioms for disabling ackerman reductions on disequalities.
