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This option only marginally helped and will be difficult to support with the new proof infrastructure.
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This commit fixes the following Coverity issues:
- 1495606: uninitialized field
- 1495605: uninitialized field
- 1488953: uninitialized field
- 1495604: mismatched iterator
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This makes it much easier to set custom properties of lemmas (e.g. preprocess) and also will allow proof tracking and debugging in the future.
This also enables a fix on the IAND branch related to preprocessing lemmas.
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This PR changes the design of ProofSkolemCache so that it has facilities for tracking proofs. This is required so that the term formula removal pass can be made proof-producing.
This makes it so that ProofSkolemCache is renamed to SkolemManager, which lives in NodeManager. Creating (most) skolems must be accompanied by a corresponding ProofGenerator that can provide the proof for the existential corresponding to their witness form.
Further updates will include refactoring the mkSkolemExists method of SkolemManager so that its contract wrt proofs is simpler.
Once all calls to mkSkolem go through the standard interface, then NodeManager::mkSkolem will be moved to SkolemManager::mkSkolemInternal.
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Also makes CVC4::theory::arith::nl namespace.
This includes some formatting changes.
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Fixes #4525. The actual problem in the issue is not that the unsat core
is satisfiable but that our unsat core check is not working as intended.
Our unsat core check uses the same `ExprManager` as the main `SmtEngine`
and thus also shares the same attributes for nodes. However, since we
have a different `SmtEngine` instance for the check, we also have
different instances of `TheoryArith`. This leads to the check failing
due to the following:
- Our only input assertion is `(> (cot 0.0) (/ 1 0)))`.
- `TheoryArith::expandDefinition()` gets called on `(> (cot 0.0) (/ 1
0))` but nothing happens.
- `TheoryArith::expandDefinition()` gets called on `(/ 1 0)`, which gets
expanded as expected but no attribute is set because it happens in a
simple `TheoryArith::eliminateOperators()` call.
- `TheoryArith::expandDefinition()` on `(cot (/ 0 1))` first expands to
`(/ 1 0)` (not cached) and then we expand it recursively to the
expected term and cache `(/ 1 0) ---> (ite (= 0 0) (divByZero 1.0) (/
1 0))`.
Up to this point, things are suboptimal but there are no correctness
issues. The problem starts when we do the same process in the unsat core
check:
- Our only input assertion is again `(> (cot 0.0) (/ 1 0)))`.
- `TheoryArith::expandDefinition()` gets called on `(> (cot 0.0) (/ 1
0))` but nothing happens.
- `TheoryArith::expandDefinition()` gets called on `(/ 1 0)`, which gets
expanded as expected but no attribute is set or checked because it
happens in a simple `TheoryArith::eliminateOperators()` call. Note
that the skolem introduced here for the division-by-zero case is
different from the skolem introduced above because this is in a
different `TheoryArith` instance that does not know the existing
skolems.
- `TheoryArith::expandDefinition()` on `(cot (/ 0 1))` first expands to
`(/ 1 0)` (not cached) and then we use the cache from our solving call
to expand it `(/ 1 0) ---> (ite (= 0 0) (divByZero 1.0) (/ 1 0))`.
Note that `divByZero` here is the skolem from the main solver.
As a result, the preprocessed assertions mix skolems from the main
`SmtEngine` with the `SmtEngine` of the unsat core check, making the
constraints satisfiable.
To solve this problem, this commit removes the caching-by-attribute
mechanism. The reason for removing it is that it is currently
ineffective (since most eliminations do not seem to be cached) and there
are caches at other levels, e.g. when expanding definitions. If we deem
the operator elimination to be a bottleneck, we can introduce a similar
mechanism at the level of `TheoryArith`.
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This is a major refactor of how operators are eliminated in arithmetic. Currently there were (at least) two things wrong:
(1) ppRewriteTerm sent lemmas on the output channel. This behavior is incompatible with how preprocessing works. In particular, this caused unconstrained simplification to be unaware of terms from such lemmas, leading to incorrect "sat" answers.
(2) Lemmas used to eliminate certain "div-like" terms were processed in a context-independent way. However, lemmas should be cached in a user-context-dependent way. This was leading to incorrect "sat" answers in incremental.
The solution to these issues is to eliminate operators via the construction of witness terms. No lemmas are sent out, and instead these lemmas are the consequence of term formula removal in the standard way.
As a result of the refactor, 2 quantifiers regressions time out due to infinite branch and bound issues (one only during --check-unsat-cores). These appear to be random and I've changed the options to avoid these issues. 3 others now have check-model warnings, which I've added --quiet to. Improving check-model will be addressed on a future PR.
This PR is not required for SMT COMP since we have workarounds that avoid both the incorrect behaviors in our scripts.
Also notice that --rewrite-divk is effectively now enabled by default always.
Fixes #4484, fixes #4486, fixes #4481.
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When we eliminate a variable x -> v during simplification, it may be the case that v contains "unevaluated" operators like forall, choice, etc. Thus, we do not produce correct models for such inputs unless simplification is disabled.
This PR ensures we only eliminate variables when v contains only evaluated operators.
Additionally, the kinds registered as unevaluated were slightly modified so that when we are in a logic like QF_LIA, there are no registered unevaluated operators, hence the check above is unnecessary. This is to minimize the performance impact of this change.
Fixes #4500.
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Renamed operator CHOICE to WITNESS, and removed it from the front end
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This splits the "non-linear solver" from "NonlinearExtension". The non-linear solver is the module that implements the inference schemas whereas NonlinearExtension is the glue code that manages the solver(s) for non-linear.
This also involves moving utilities from the non-linear solver to their own file.
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Fixes #3971 and fixes #3991. In incremental mode, the logic can change from one
(check-sat) call to another. In the reported issue, we start with QF_NIA
but then switch to QF_UFNIA because there is a div term (which has a UF in
its expanded form). Dealing with this issue is challenging in general. As a
result, we have decided not to allow theory widening in
Theory::expandDefinitions() anymore but instead to do it eagerly in
SmtEngine::setDefaults().
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This commit adds statistics for string rewrites. This is work towards proof
support in the string solver. At a high level, this commit adds a pointer to a
`SequenceStatistics` in the rewriters and modifies
`SequencesRewriter::returnRewrite()` to count the rewrites done. In practice,
to make this work requires a couple of changes, some of them temporary:
- We can't have a single `Rewriter` instance shared between different
`SmtEngine` instances anymore. Thus the `Rewriter` is now owned by the
`SmtEngine` and calling the rewriter retrieves the rewriter associated with
the current `SmtEngine`. This is a temporary workaround before we get rid of
singletons.
- Methods in the `SequencesRewriter` and the `StringsRewriter` are made
non-`static` because they need access to the statistics instance.
- `StringsEntail` now has non-`static` methods because it needs a reference to
the sequences rewriter that it can call.
- The interaction between the `StringsRewriter` and the `SequencesRewriter`
changed: the `StringsRewriter` is now a proper `TheoryRewriter` that inherits
from `SequencesRewriter` and calls its `postRewrite()` before applying its
own rewrites (this is essentially a reversal of roles from before: the
`SequencesRewriter` used to call `static` methods in the `StringsRewriter`).
- The theory rewriters are now owned by the individual theories. This design
mirrors the `EqualityEngine`s owned by the individual theories.
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Until now, the `Rewriter` was responsible for creating `TheoryRewriter`
instances. This commit adds a method `mkTheoryRewriter()` that theories
override to create an instance of their corresponding theory rewriter.
The advantage is that the theories can pass additional information to
their theory rewriter (e.g. a statistics object).
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* Attempting to split transcendental function solver
* Clean
* Format
* More
* Format
* Attempt link
* Format
* Fix
* Another refactor
* More
* More
* Rename
* Format
Co-authored-by: Ahmed Irfan <43099566+ahmed-irfan@users.noreply.github.com>
Co-authored-by: Aina Niemetz <aina.niemetz@gmail.com>
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* unit-cude test wip
* test for wip unit cube test
* fixed simple rounding
* wip
* Passing tests except for sat vs unknown ones
* added flag for cube test
* put example back to normal
* Fixed for style guidelines.
* fixed rewrite bug
* removed extra comments
* unit-cude test wip
* test for wip unit cube test
* fixed simple rounding
* wip
* Passing tests except for sat vs unknown ones
* added flag for cube test
* put example back to normal
* Fixed for style guidelines.
* fixed rewrite bug
* removed extra comments
* Small fixes based on PR feedback
* replace NodeManager::currentNM with nm and clang formatted
* renamed test
* Added a regression test that triggers branch and bound
* Added ; COMMAND-LINE: --arith-brab
* Updated arith-brab test
* arith-brab enabled by default
* Added --nl-ext-tplanes to regress0/nl/ext-rew-aggr-test.smt2
Co-authored-by: Amalee Wilson <amalee@cis.uab.edu>
Co-authored-by: Ahmed Irfan <43099566+ahmed-irfan@users.noreply.github.com>
Co-authored-by: Andrew Reynolds <andrew.j.reynolds@gmail.com>
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Fixes #4112.
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I'll remove the error later
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Before, a "simple farkas proof" was one that just applied the farkas
lemma.
Now it allows for the antecedents to (optionally) be tightened.
Note that hasSimpleFarkasProof was (and is) dead code.
We will use it to decide whether to print a proof or a hole.
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* Fix assertion in resolution bound inferences
* Format
* Minor
Co-authored-by: Ahmed Irfan <43099566+ahmed-irfan@users.noreply.github.com>
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Fixes #3803.
When non-linear arithmetic determines there is a model, then it should not send model values for multiplication terms that the linear solver assigned when abstracting (non-linear) multiplication. This avoids conflicts if the non-linear solver changed a value for a variable occurring in a non-linear monomial. This avoids check-model failures.
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Fixes #3952 and fixes #3940 and fixes #3941 and fixes #3968.
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This PR refactors and fixes how bounds are set for transcendental functions. The new code ensures that all transcendental function applications are given bounds. (Our previous failures to do so were hindering our ability to say "sat", due to NlModel::checkModel failures).
There were previously two issues on why transcendental function applications were not being assigned bounds:
"Slave" transcendental functions (e.g. those that we reduce via sin(t) = sin(y) ^ -pi <= y <= pi ^ y + 2*pi*N = t) were not being given bounds explicitly,
Transcendental functions that are congruent to others (e.g. f(x) where f(y) exists and x=y in the current context) were being ignored and hence not bound.
This PR clarifies the master/slave relationship that tracks which transcendental function applications have been purified, and furthermore tracks congruence classes.
The setting of bounds and the check-model is further simplified by setting bounds on the original terms, whereas the current code sets bounds on the model values of terms. In other words, previously if we had term sin(y) and y^M = c, then we'd set bounds for sin(c), whereas the new code sets the bound on sin(y) directly.
Fixes #3783. We answer unknown without an assertion failure on that benchmark now. Further work based on ignoring literals from internally generated lemmas is necessary for solving it sat.
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Fixes #3944.
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This rule is used when a bound on an integer expression is tightened
because of integer reasoning.
Before this rule was subsumed by IntHoleAP, a catch-all rule for integer
reasoning. We are now articulating IntTightenAP separately, because we
can produce proofs for it.
For IntHoleAP, we will have to omit a hole.
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This reverts commit c360b3af4371cf871935a8bae96be5f8fecf741b.
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This rule is used when a bound on an integer expression is tightened
because of integer reasoning.
Before this rule was subsumed by IntHoleAP, a catch-all rule for integer
reasoning. We are now articulating IntTightenAP separately, because we
can produce proofs for it.
For IntHoleAP, we will have to omit a hole.
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Fixes all -Wshadow warnings and enables the -Wshadow compile flag globally.
Co-authored-by: Clark Barrett <barrett@cs.stanford.edu>
Co-authored-by: Andres Noetzli <andres.noetzli@gmail.com>
Co-authored-by: Aina Niemetz <aina.niemetz@gmail.com>
Co-authored-by: Alex Ozdemir <aozdemir@hmc.edu>
Co-authored-by: makaimann <makaim@stanford.edu>
Co-authored-by: yoni206 <yoni206@users.noreply.github.com>
Co-authored-by: Andrew Reynolds <andrew.j.reynolds@gmail.com>
Co-authored-by: AleksandarZeljic <zeljic@stanford.edu>
Co-authored-by: Caleb Donovick <cdonovick@users.noreply.github.com>
Co-authored-by: Amalee <amaleewilson@gmail.com>
Co-authored-by: Scott Kovach <dskovach@gmail.com>
Co-authored-by: ntsis <nekuna@gmail.com>
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Work towards CVC4/cvc4-projects#113 and #3783.
This PR adds the ability to mark certain literals as being tautological, since they can be assumed to hold in all models. This is important for internally generated literals whose purpose is to guide models generated by the linear solver but should not hinder our ability to answer "sat".
This PR is required for further refactoring of check-model for transcendental functions.
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Fixes #3647.
Previously, when doing incremental linearization for transcedental functions, we would add points to the list of secant points at the time when linearization lemmas were generated. However, our strategy has been updated such that lemmas may be abandoned (say in the case that a higher priority lemma is found). Thus, our list of secant points had spurious points corresponding to lemmas that weren't sent. This led to assertion failures, and likely led to gaps in our linearization, hindering our ability to say sat/unsat.
This PR introduces a "lemma side effect" class to ensure that modifications to the state of the nonlinear solver are in sync with the lemmas we send out.
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Fixes #3300.
This adds an option --model-witness-choice that ensures that choices in models are of the form (choice ((x Int)) (or (= x c) P)), which is helpful if the user wants to know a potential value in the range of the choice.
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This commit adds statistics for all resource steps. A resource statistic is incremented by 1 if the resource is spent (via `spendResource`).
Fixes #3751.
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rewrite (#3747)
* Fix bounds for negative sine apps
* Format
* Comment
Co-authored-by: Ahmed Irfan <43099566+ahmed-irfan@users.noreply.github.com>
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This was introduced 7 years ago in https://github.com/CVC4/CVC4/commit/9098391fe334d829ec4101f190b8f1fa21c30752.
This impacted any case of integer div/mod of the form `(mod c t)` or `(div c t)` where c is a constant and `t` is not.
Fixes #3765.
Also improves `--dump=t-lemmas` trace to result in smt-lib compatible output, which was required for debugging this.
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(#3739)
* Fix non-linear equality solving that involves mixed real/integer.
* Format
* Fix
* Revert
Co-authored-by: Ahmed Irfan <43099566+ahmed-irfan@users.noreply.github.com>
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Co-authored-by: Ahmed Irfan <43099566+ahmed-irfan@users.noreply.github.com>
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* Fix for 3614
* Add regression
* Remove regression
Co-authored-by: Ahmed Irfan <43099566+ahmed-irfan@users.noreply.github.com>
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transcendentals (#3577)
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This commit adds support for code generation of options with modes (enums). From now on option enums can be specified in the corresponding *.toml files without the need of extra code. All option enums are now in the options namespace.
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This commit changes theory rewriters to be non-static. This refactoring
is needed as a stepping stone to making our rewriter configurable: If we
have multiple solver objects with different rewrite configurations, we
cannot use `static` variables for the rewriter table in the BV rewriter
for example. It is also in line with our goal of getting rid of
singletons in general. Note that the `Rewriter` class is still a
singleton, which will be changed in a future commit.
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solver (#3525)
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