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This fixes an unsoundness issue in the sets + cardinality solver.
One rule of this solver applies in sets when two parents of a child of a cardinality graph are equal, in which case we know that child or one of its siblings must be equal to the opposite parent. For example, this rule tells us that:
if T = (union T S), then (intersect T S) = S.
The explanation of this rule could consider the representative term of one the parents instead of the term itself say (union T S) is representative T, giving the unsound inference: if (union T S) = (union T S), then (intersect T S) = S. This ensures we use the original terms.
This PR also does some minor cleanup.
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Fixes cases of satisfiable unsat cores when proofs are enabled.
Unfortunately, this bug was also preventing us from doing the final scope check for all proof checking. As this was not being tested, this PR uncovers that proof checking is now failing on 6 regressions. I'm disabling proof checking here and will address these issues on later PRs.
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This makes it so that we attempt evaluation + rewriting on applications of operators that do not always evaluate, and return constants in case the evaluation was successful.
This fixes warnings for check-models on 43 of our regressions, and also uncovered one regression where our model was wrong but check-models silently succeeded. I've opened CVC4/cvc4-projects#276 for fixing the latter.
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Fixes #5942.
This benchmark was fixed by recent changes to ppRewrite.
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Fixes #4370.
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We were getting types for set singleton/membership in a way that was unsafe for subtyping, which was leading to incorrectly computing care graphs for sets of reals.
Fixes #5705.
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This commit removes parser and printer support for old SMT-LIB standards and also converts all regression tests to 2.6.
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In rare cases, theory combination would be run when theory engine still needs check. This was limited to cases where the output channel is used but no lemmas were sent (TheoryEngine::needCheck() vs. d_lemmasAdded).
This led to problems in the theory of sets, which does not run a full effort check if theory engine needs check (since it knows it will be called to check again). However, running theory combination in these cases is not safe since theory of sets computes information pertaining to the care graph during its full effort check. Running theory combination otherwise would lead to theory of sets using stale data, leading to crashes due to terms not appearing in the equality engine.
This fixes #4124 (which appears not to trigger on master anyways currently).
This bug has also appeared on my sat relevancy development branch, hence fixing on master.
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Currently --check-models is implemented by replaying several preprocessing steps, including theory-specific expand definitions, and then checking whether the result evaluates to true.
However, by having --check-models rely on complex preprocessing machinery defeats its purpose, as these steps are part of its trusted base.
Moreover, issue #5645 demonstrates that this may lead to spurious errors where we incorrectly conclude that an input assertion is false, when it is not.
This PR significantly simplifies --check-models so that it only relies on define-fun expansion + rewriting + evaluation. This ensures that --check-models is "sound" i.e. it does not falsely report a formula as evaluating to false. As a consequence, this makes check-models give warnings more often, i.e. when partial operators are involved, thus -q is added to silence warnings on some regressions.
A followup PR will use a satisfiability check on the input formula post-expand-definitions to properly implement a trustworthy version of check-models that is robust for partial operators.
Fixes #5645.
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This adds a net +82 regressions to regress[0-2] and adds several additional disabled regressions to regress3 and regress4. This involved fixing the status on several regressions, and ensuring CMakeLists.txt includes all files (exactly once) in the test/regress/ subdirectory.
It also moves several regressions to the proper regression levels (those that take >30 seconds in debug are moved to regress3+).
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This updates the preprocessor so that expand definitions does not expand theory symbols at the beginning of preprocessing.
This also restores the previous expandDefinitions method in arithmetic, which is required for correctly interpreting division by zero in models, but should not be applied at the beginning of preprocessing. Moreover it ensures that only partial operators are eliminated in arithmetic expandDefinitions, which required an additional argument partialOnly to arith::OperatorElim.
This adds -q to suppress warnings for many quantified regressions which now emit warnings with --check-model. This will be addressed later as part of CVC4/cvc4-wishues#43.
The purpose of this PR is two-fold:
(1) Currently our responses to get-value are incorrect for partial operators like div, mod, seq.nth since partial operators can be left unevaluated.
(2) The preprocessor should have the opportunity to rewrite and eliminate extended operators before they are expanded. This is required for addressing performance issues for non-linear arithmetic. It is also required for ensuring that trigger selection can be done properly for datatype selectors (to be addressed on a later PR).
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This PR makes it so that extended arithmetic operators are not expanded during expand definitions. Instead they are eliminated at theory preprocessing, which occurs as the last step of preprocessing.
The motivation for this is three fold:
(1) Some quantified LIA benchmarks lead to CVC4 failing to eliminate div functions from quantifier instantiation, this leads to spurious logic failures. A regression is included, which now is correctly solved.
(2) We should allow better rewriting and preprocessing for extended arithmetic functions, especially for div/mod which is important for many users of QF_NIA.
(3) More generally,Theory::expandDefinitions will be deleted. All functionalities in expandDefinitions should move to Theory::ppRewrite.
This changes impacts many benchmarks that involve non-linear and quantifiers:
Many benchmarks (as expected) give a warning during check-models since (/ n 0) cannot be evaluated. I've added -q to disable these warnings. Fully addressing this is part of an agenda to improve our support for --check-models.
Several fuzzing benchmarks involving NL+quantifiers now time out. However, several can be solved by --sygus-inst, which is now the preferred instantiation strategy for NL+quantifiers.
2 other non-linear regressions time out, which are disabled in this PR.
one sygus-inference benchmark (regress1/sygus/issue3498.smt2), now correctly times out (previously it did not timeout since the preprocessor was unable to apply sygus-inference and resorted to normal methods, now sygus-inference can apply but as expected times out).
Fixes #5237.
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This PR fixes issue #5342 by adding the rewrite rule (setminus A (setminus A B)) = (intersection A B).
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This PR fixes #5271 by splitting on the equality of set members which ensures members are distinct when collectModelInfo is called.
Co-authored-by: Andrew Reynolds andrew-reynolds@uiowa.edu
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This PR fixes #5309 by ensuring singleton terms are added to the model builder as representatives.
Co-authored-by: Andrew Reynolds andrew-reynolds@uiowa.edu
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This pull request adds a new operator is_singleton for sets to determine whether a set is a singleton.
Before this operator, the user either uses an existential quantifier or the cardinality operator in smtlib. The former affects the performance especially when polarity is negative. The latter requires the cardinality extension in sets theory.
The implementation of is_singleton only uses an internal existential quantifier with the hope of optimizing it later.
New rewriting rules:
(is_singleton (singleton x)) is rewritten as true.
(is_singleton A) is rewritten as (= A (singleton x)) where x is a fresh skolem of the same type of elements of A.
(choose (singleton x)) is rewritten as x.
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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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Fixes #4391.
The sets cardinality cycle rule is analogous to the S-Cycle rule for strings (see Liang et al CAV 2014). This rule is typically never applied but can be applied in rare cases where theory combination does not determine a correct arrangement of equalities over sets terms that is consistent with the arithmetic arrangement of their cardinalities at full effort. Notice the regression from #4391 has non-linear arithmetic, (mod 0 d), which is translated to UF.
The cardinality cycle rule had a bug: it assumed that cycles that were encountered were loops e1 = e2 = ... = e1 but in general they can be lassos e1 = ... = e2 = ... = e2. This ensures the Venn region cycle e2 = ... = e2 is the conclusion in this case, instead of unsoundly concluding e1 = ... = e2.
Strings does not have a similar issue:
https://github.com/CVC4/CVC4/blob/master/src/theory/strings/core_solver.cpp#L488
Here, when a cycle is encountered, it is processed at the point in traversal where the loop is closed.
This is not critical for SMT-COMP but should be in the 1.8 release.
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This commit converts all v2.5 smt2 regressions to v2.6 (except for regress/regress0/lang_opts_2_5.smt2).
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This PR enables THEORY_UF by default for sets and adds the operator CHOOSE for sets which returns an element from a given set. The semantics is as follows:
If a set A = {x}, then the term (choose A) is equivalent to the term x.
If the set is empty, then (choose A) is an arbitrary value.
If the set has cardinality > 1, then (choose A) will deterministically return an element in A.
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* Fixed bug 3662
* format
* small change
* added bug3663.smt2 file
* throw Logic Exception
* throw Logic Exception
* ;EXIT: 1
Co-authored-by: Andrew Reynolds <andrew.j.reynolds@gmail.com>
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* rewrote set cardinality for finite-types
* small changes and format
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Until now, regression tests were split across tens of different
Makefile.am, which required a lot of code duplication and does not
really seem to be in the spirit of automake. If we want to change the
LOG_COMPILER/LOG_DRIVER for example, we have to change every single
Makefile.am, which is cumbersome (I was able to get something
semi-working by exporting those variables but it didn't seem very
clean). Additionally, it made the output of the regression tests fairly
verbose and split the output across multiple log files. Finally
it also limited parallelism when running the regression tests (this fix lowers
the time it takes to run regression level 1 from 3m to 1m45s on my
machine with 16 threads).
This commit moves all the regression tests into
test/regress/Makefile.tests and changes test/regress/Makefile.am to deal
with this new structure. Finally, it changes how the test summary in
test/Makefile.am is produced: instead of relying on the log files for
the subdirectories, it greps for the test results in the log files of
the individual tests. Not the most elegant solution but we should
probably anyway delegate that task to a Python script at some point.
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