Difference between revisions of "About CVC4"
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| − | CVC4 is a [http://en.wikipedia.org/wiki/Satisfiability_Modulo_Theories Satisifiability Modulo Theories (SMT) ] (for a more formal introduction to SMT see the following book chapter [https://cs.nyu.edu/~barrett/pubs/BSST09.pdf Satisfiability Modulo Theories] ). Technically, it is an automated validity checker for a many-sorted (i.e., typed) first-order logic with built-in theories. | + | CVC4 is a solver for [http://en.wikipedia.org/wiki/Satisfiability_Modulo_Theories Satisifiability Modulo Theories (SMT) ] (for a more formal introduction to SMT see the following book chapter [https://cs.nyu.edu/~barrett/pubs/BSST09.pdf Satisfiability Modulo Theories] ). Technically, it is an automated validity checker for a many-sorted (i.e., typed) first-order logic with built-in theories. |
CVC4 currently has support for the following theories: | CVC4 currently has support for the following theories: | ||
* equality over free (aka uninterpreted) function and predicate symbols | * equality over free (aka uninterpreted) function and predicate symbols | ||
| − | * real and integer linear arithmetic | + | * real and integer linear arithmetic |
* bit-vectors, | * bit-vectors, | ||
* arrays | * arrays | ||
| Line 9: | Line 9: | ||
* records | * records | ||
* user-defined inductive data types. | * user-defined inductive data types. | ||
| + | |||
| + | It also supports the use of quantifiers through heuristic instantiation and can produce models for quantifier-free satisfiable queries. | ||
=History of CVC= | =History of CVC= | ||
Revision as of 17:29, 30 November 2012
CVC4 is a solver for Satisifiability Modulo Theories (SMT) (for a more formal introduction to SMT see the following book chapter Satisfiability Modulo Theories ). Technically, it is an automated validity checker for a many-sorted (i.e., typed) first-order logic with built-in theories.
CVC4 currently has support for the following theories:
- equality over free (aka uninterpreted) function and predicate symbols
- real and integer linear arithmetic
- bit-vectors,
- arrays
- tuples
- records
- user-defined inductive data types.
It also supports the use of quantifiers through heuristic instantiation and can produce models for quantifier-free satisfiable queries.
History of CVC
The Cooperating Validity Checker series has a long history. The Stanford Validity Checker (SVC) came first in 1996, incorporating theories and its own SAT solver. Its successor, the Cooperating Validity Checker (CVC), had a more optimized internal design, produced proofs, used the Chaff SAT solver, and featured a number of usability enhancements. Its name comes from the cooperative nature of decision procedures in Nelson-Oppen theory combination, which share amongst each other equalities between shared terms. CVC Lite, first made available in 2003, was a rewrite of CVC that attempted to make CVC more flexible (hence the "lite") while extending the feature set: CVC Lite supported quantifiers where its predecessors did not. CVC3 was a major overhaul of portions of CVC Lite: it added better decision procedure implementations, added support for using MiniSat in the core, and had generally better performance.
CVC4 is the new version, the fifth generation of this validity checker line that is now celebrating sixteen years of heritage. It represents a complete re-evaluation of the core architecture to be both performant and to serve as a cutting-edge research vehicle for the next several years. Rather than taking CVC3 and redesigning problem parts, we've taken a clean-room approach, starting from scratch. Before using any designs from CVC3, we have thoroughly scrutinized, vetted, and updated them. Many parts of CVC4 bear only a superficial resemblance, if any, to their correspondent in CVC3.
However, CVC4 is fundamentally similar to CVC3 and many other modern SMT solvers: it is a DPLL(T) solver, with a SAT solver at its core and a delegation path to different decision procedure implementations, each in charge of solving formulas in some background theory.
The re-evaluation and ground-up rewrite was necessitated, we felt, by the performance characteristics of CVC3. CVC3 has many useful features, but some core aspects of the design led to high memory use, and the use of heavyweight computation (where more nimble engineering approaches could suffice) makes CVC3 a much slower prover than other tools. As these designs are central to CVC3, a new version was preferable to a selective re-engineering, which would have ballooned in short order. Some specific deficiencies of CVC3 are mentioned in this article.
