Fix model unsoundness in bounded set quantification #11268
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| (set-option :finite-model-find true) | ||
| (set-option :fmf-bound true) | ||
| (declare-const r (Set (Tuple Int))) | ||
| (declare-const M (Set (Tuple Int Bool))) |
There was a problem hiding this comment.
This line can be deleted
tomerH98
pushed a commit
to tomerH98/cvc5_nesteddt
that referenced
this pull request
Oct 28, 2024
This bug was introduced in cvc5#2200. The PR cvc5#10586 modified our handling of set+cardinality+quantifiers but did not fix the issue. In the former PR, we incorrectly computed the cardinality of set values. In the latter PR, we no longer introduced set.card terms when finding finite bounds for bounded set quantification, to avoid issues of incompleteness at the quantifier-free level. However, in doing so, we could ignore cardinality for bounds altogether, potentially leading to model unsoundness. This PR keeps cardinality in bounding terms, but eliminates literals of the form `(set.card S) < n` eagerly, based on finite unions of `set.choose` terms.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This bug was introduced in #2200. The PR #10586 modified our handling of set+cardinality+quantifiers but did not fix the issue.
In the former PR, we incorrectly computed the cardinality of set values. In the latter PR, we no longer introduced set.card terms when finding finite bounds for bounded set quantification, to avoid issues of incompleteness at the quantifier-free level. However, in doing so, we could ignore cardinality for bounds altogether, potentially leading to model unsoundness.
This PR keeps cardinality in bounding terms, but eliminates literals of the form
(set.card S) < neagerly, based on finite unions ofset.chooseterms.