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This commit replaces (old) internal string kind names to match the API / smt2 standard names.
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Fixes #6057. The reductions of `str.replace_re` and `str.replace_re_all`
were not correctly enforcing that the operations replace the _first_
occurrence of some regular expression in a string. This commit fixes the
issue by introducing a new operator `str.indexof_re(s, r, n)`, which,
analoguously to `str.indexof`, returns the index of the first match of
the regular expression `r` in `s`. The commit adds basic rewrites for
evaluating the operator as well as its reduction. Additionally, it
converts the reductions of `str.replace_re` and `str.replace_re_all` to
use that new operator. This simplifies the reductions of the two
operators and ensures that the semantics are consistent between the two.
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applicable (#6529)
Fixes #6510.
This PR also eliminates a deprecated variant mkBooleanTermVariable from SkolemManager.
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This formalizes more skolems in preparation for moving Theory::expandDefinitions to Rewriter::expandDefinitions.
It also adds proof support for datatypes purification.
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This is in preparation for refactoring skolem creation throughout the code base to improve proofs and migrate Theory::expandDefinitions to Rewriter::expandDefinitions.
This PR also eliminates some unused code in TheoryArithPrivate.
Followup PRs will start formalizing/eliminating calls to mkDummySkolem.
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This PR ensures that several optimizations are not performed in the reference implementation of skolem sharing (d_useOpts=false). This is to ensure that the many of the rules in the strings proof checker do not depend on the rewriter.
These errors were caught by the LFSC proof checker.
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This uses BoundVarManager for several key places where bound variables are introduced, including for array extensionality witness terms, string preprocessing, quantifiers rewriting, and skolemization.
This is motivated by making certain steps in solving deterministic for the sake of proofs, and gives a more consistent pattern in general for constructing bound variables.
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Expand definitions for sequences was wrong in two ways: (1) we replaced str.from_code with a witness term. This led to it being unevaluatable in models. (2) we did not handle seq.nth, meaning its model value was unevaluatable if it was out of bounds. Now it evaluates the value of the uninterpreted function we replace with.
This corrects both issues and adds a regression to demonstrate both kinds of terms evaluate correctly.
To do this, I added a helper function to skolem cache as well as a new (internal-only) kind SEQ_NTH_TOTAL. Notice applications of this kind should only be used for model evaluation.
Notice this fixes several check-model warnings in the regressions. It still does not fix others since other things must be corrected for model evaluation (e.g. expandDefinitions must be applied on theory assertions for --debug-check-models). This will be done in later PRs.
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This PR updates the update-copyright.pl script to also update/add copyright headers to CMake specific files. It further fixes a small typo in the header.
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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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This PR makes strings skolem cache call the ProofSkolemCache. This is required for proper proof checking, as it makes all skolems be associated with their formal definition, encapsulated by a witness term.
It furthermore makes skolem sharing more uniform and aggressive by noting that most string skolems correspond to purification variables (typically for some substr term). A purification variable for a term that rewrites to a constant can be replaced by the constant itself.
It also introduces an attribute IndexVarAttribute which is used to ensure reductions involving universal variables are deterministic.
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This fixes a soundness issue in strings caused by an incorrect skolem share.
This adds a regression that corresponds to the rewrite that this skolem share was justified by, which is "sat" (the rewrite does not hold). This benchmark in fact was answered "unsat" by CVC4 prior to this PR.
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This is in preparation for making the strings rewriter configurable for stats.
This moves all utility functions from SequencesRewriter to a proper place. This includes three new groupings of utility functions: those involving arithmetic entailments, those involving string entailments, those involving regular expression entailments. Here, "entailments" loosely means any question regarding a (set of) terms or formulas.
No major code changes. Added some missing documentation and lightly cleaned a few blocks of code in cpp.
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Organization towards theory of sequences.
The motivation of this PR is to ensure that string-specific operators in the rewriter are in their own file; thus the use of mkConst<String> / getConst<String> is allowable in rewriter_str.cpp.
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This PR makes the skolem normalization in the string solver quite a bit
more aggressive by reducing more skolems to prefix and suffix skolems.
Experiments show that this PR significantly improves performance on CMU
benchmarks.
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In certain cases, we can share skolems between similar reductions, e.g.
`(str.replace x y z)` and `(str.replace (str.substr x 0 n) y z)` because the
first occurrence of `y` in `x` has to be the first occurrence
of `y` in `(str.substr x 0 n)` (assuming that `y` appears in both, otherwise the value of
the skolems does not matter). This commit adds a helper function in the
skolem cache that does some of those simplifications.
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(#2478)
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This PR is in preparation for doing more aggressive caching of skolems (for example, in the strings preprocessor).
It refactors sendLengthLemma -> registerLength, which unifies how length lemmas for skolems and other string terms are handled.
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