| Age | Commit message (Collapse) | Author |
|---|
|
This commit adds testing infrastructure for LFSC signatures that is
enabled when CVC4 is configured with LFSC. The testing infrastructure
adopts run_test.py from https://github.com/CVC4/LFSC with minor
modifications (mainly adding support for a list of include directories
that are searched to resolve *.plf dependencies). The commit uses the
existing examples and test files from proofs/signatures as the initial
set of tests.
Co-authored-by: Alex Ozdemir aozdemir@hmc.edu
|
|
This comment was slightly out-of-date.
|
|
|
|
This commit enables DRAT-optimization, which consists of two sub-processes:
1. removing unnecessary instructions from DRAT-proofs and
2. not proving clauses which are not needed by DRAT proofs.
These changes have the effect of dramatically shortening some some bit-vector proofs. Specifically, proofs using lemmas in the ER, DRAT, and LRAT formats, since proofs in any of these formats are derived from a (now optimized!) DRAT proof produced by CryptoMiniSat. What follows is a description of the main parts of this PR:
## DRAT Optimization
The DRAT-optimization is done by `drat-trim`, which is bundled with `drat2er`. The (new) function `ClausalBitVectorProof::optimizeDratProof` is our interface to the optimization machinery, and most of the new logic in this PR is in that function.
## CNF Representation
The ability to not prove unused clauses requires a slight architectural change as well. In particular, we need to be able to describe **which** subset of the original clause set actually needs to be proved. To facilitate this, when the clause set for CryptoMiniSat is first formed it is represented as a (a) map from clause indices to clauses and (b) a list of indices. Then, when the CNF is optimized, we temporarily store a new list of the clauses in the optimized formula. This change in representation requires a number of small tweaks throughout the code.
## Small Fixes to Signatures
When we decided to check and accept two different kinds of DRAT, some of our DRAT-checking broke. In particular, when supporting one kind of DRAT, it is okay to `fail` (crash) when a proof fails to check. If you're supporting two kinds of DRAT, crashing in response to the first checker rejecting the proof denies the second checker an opportunity to check the proof. This PR tweaks the signatures slightly (and soundly!) to do something else instead of `fail`ing.
|
|
* Extended DRAT signature to operational DRAT
The DRAT signature now supports both operational and specified DRAT.
That is, either kind of proof will be accepted.
The goal of this implementation of operational DRAT was to re-use as
much of the specified DRAT machinery as possible. However, by writing a
separate operational signature, we could make it much more efficient
(after all, operational DRAT came about because of a push for efficient
cheking).
You can run the new AND old DRAT tests by running
```
lfscc sat.plf smt.plf lrat.plf drat.plf drat_test.plf
```
* Apply suggestions from code review (Yoni)
Co-Authored-By: alex-ozdemir <aozdemir@hmc.edu>
|
|
* Bugfix: LFSC clause equality
My implementation of clause equality had an undocumented assumption that
the clauses didn't have any duplicate literals. Now that assumption is
gone, and the tests suite has been expanded.
* Added an empty clause test
* Typo fix: Yoni
Co-Authored-By: alex-ozdemir <aozdemir@hmc.edu>
* Address Yoni's comments
* Remove a duplicate clause_eq test.
* Add an ordering clause_eq test.
* Improve the documentation of clause_eq.
|
|
* Extended Resolution Signature
While extended resolution is a fairly general technique, the paper
"Extended Resolution Simulates DRAT" / the drat2er uses exactly one new
type of rule: definitions of the form
new <=> old v (~l_1 ^ ~l_2 ^ ... ^ ~l_n)
This PR adds axioms supporting this kind of definition, and adds a test
making use of those new axioms. The axioms support the following ideas:
1. Introducing a **fresh** variable, defined in the form above
2. Clausifying that definition to produce proofs of $$ n + 2 $$ new
clauses in the form of two clauses, and a cnf with $$ n $$ clauses
3. An axiom for unrolling the proof of the cnf into proofs of the
original clauses.
* Addressing Yoni's comments
1. Added a new (trivial) test
2. Improved a bunch of documentation
* Update proofs/signatures/er.plf
Co-Authored-By: alex-ozdemir <aozdemir@hmc.edu>
* Removed references to RATs from the signature
There are still a few references in the header comment.
* Aside on continuations
* Scrap the elision annotations
|
|
* DRAT signature
Added the DRAT signature to CVC4.
We'll need this in order to compare three BV proof pipelines:
1. DRAT -> Resolution -> Check
2. DRAT -> LRAT -> Check
3. DRAT -> Check (this one!)
Tested the signature using the attached test file. i.e. running
```
lfscc sat.plf smt.plf lrat.plf drat.plf drat_test.plf
```
* Added type annotations for tests
* Respond to Yoni's review
* Apply Yoni's suggestions from code review
Documentation polish
Co-Authored-By: alex-ozdemir <aozdemir@hmc.edu>
* Whoops, missed a spot or two
|
