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Diffstat (limited to 'src/proof/er/er_proof.h')
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diff --git a/src/proof/er/er_proof.h b/src/proof/er/er_proof.h new file mode 100644 index 000000000..0a0038738 --- /dev/null +++ b/src/proof/er/er_proof.h @@ -0,0 +1,208 @@ +/********************* */ +/*! \file er_proof.h + ** \verbatim + ** Top contributors (to current version): + ** Alex Ozdemir + ** This file is part of the CVC4 project. + ** Copyright (c) 2009-2019 by the authors listed in the file AUTHORS + ** in the top-level source directory) and their institutional affiliations. + ** All rights reserved. See the file COPYING in the top-level source + ** directory for licensing information.\endverbatim + ** + ** \brief ER Proof Format + ** + ** Declares C++ types that represent an ER/TRACECHECK proof. + ** Defines serialization for these types. + ** + ** You can find details about the way ER is encoded in the TRACECHECK + ** format at these locations: + ** https://github.com/benjaminkiesl/drat2er + ** http://www.cs.utexas.edu/users/marijn/publications/ijcar18.pdf + ** + **/ + +#include "cvc4_private.h" + +#ifndef __CVC4__PROOF__ER__ER_PROOF_H +#define __CVC4__PROOF__ER__ER_PROOF_H + +#include <memory> +#include <vector> + +#include "proof/clause_id.h" +#include "prop/sat_solver_types.h" + +namespace CVC4 { +namespace proof { +namespace er { + +using ClauseUseRecord = std::vector<std::pair<ClauseId, prop::SatClause>>; + +/** + * A definition of the form: + * newVar <-> p v (~x_1 ^ ~x_2 ^ ... ^ ~x_n) + */ +struct ErDefinition +{ + ErDefinition(prop::SatVariable newVariable, + prop::SatLiteral oldLiteral, + std::vector<prop::SatLiteral>&& otherLiterals) + : d_newVariable(newVariable), + d_oldLiteral(oldLiteral), + d_otherLiterals(otherLiterals) + { + } + + // newVar + prop::SatVariable d_newVariable; + // p + prop::SatLiteral d_oldLiteral; + // A list of the x_i's + std::vector<prop::SatLiteral> d_otherLiterals; +}; + +// For representing a clause's index within a TRACECHECK proof. +using TraceCheckIdx = size_t; + +/** + * A single line in a TRACECHECK proof. + * + * Consists of the index of a new clause, the literals of that clause, and the + * indices for preceding clauses which can be combined in a resolution chain to + * produce this new clause. + */ +struct TraceCheckLine +{ + TraceCheckLine(TraceCheckIdx idx, + std::vector<prop::SatLiteral>&& clause, + std::vector<TraceCheckIdx>&& chain) + : d_idx(idx), d_clause(clause), d_chain(chain) + { + } + + // The index of the new clause + TraceCheckIdx d_idx; + // The new clause + std::vector<prop::SatLiteral> d_clause; + /** + * Indices of clauses which must be resolved to produce this new clause. + * While the TRACECHECK format does not specify the order, we require them to + * be in resolution-order. + */ + std::vector<TraceCheckIdx> d_chain; +}; + +/** + * A TRACECHECK proof -- just a list of lines + */ +struct TraceCheckProof +{ + static TraceCheckProof fromText(std::istream& in); + TraceCheckProof() : d_lines() {} + + // The lines of this proof. + std::vector<TraceCheckLine> d_lines; +}; + +/** + * An extended resolution proof. + * It supports resolution, along with extensions of the form + * + * newVar <-> p v (~x_1 ^ ~x_2 ^ ... ^ ~x_n) + */ +class ErProof +{ + public: + /** + * Construct an ER proof from a DRAT proof, using drat2er + * + * @param usedClauses The CNF formula that we're deriving bottom from. + * @param dratBinary The DRAT proof from the SAT solver, as a binary stream. + */ + static ErProof fromBinaryDratProof(const ClauseUseRecord& usedClauses, + const std::string& dratBinary); + + /** + * Construct an ER proof from a TRACECHECK ER proof + * + * This basically just identifies groups of lines which correspond to + * definitions, and extracts them. + * + * @param usedClauses The CNF formula that we're deriving bottom from. + * @param tracecheck The TRACECHECK proof, as a stream. + */ + ErProof(const ClauseUseRecord& usedClauses, TraceCheckProof&& tracecheck); + + /** + * Write the ER proof as an LFSC value of type (holds cln). + * The format is from the LFSC signature er.plf + * + * Reads the current `ProofManager` to determine what the variables should be + * named. + * + * @param os the stream to write to + */ + void outputAsLfsc(std::ostream& os) const; + + const std::vector<ClauseId>& getInputClauseIds() const + { + return d_inputClauseIds; + } + + const std::vector<ErDefinition>& getDefinitions() const + { + return d_definitions; + } + + const TraceCheckProof& getTraceCheckProof() const { return d_tracecheck; } + + private: + /** + * Creates an empty ErProof. + */ + ErProof() : d_inputClauseIds(), d_definitions(), d_tracecheck() {} + + /** + * Computes the pivots on the basis of which an in-order resolution chain is + * resolved. + * + * c0 c1 + * \ / Clauses c_i being resolved in a chain around + * v1 c2 pivots v_i. + * \ / + * v2 c3 + * \ / + * v3 c4 + * \ / + * v4 + * + * + * @param chain the chain, of N clause indices + * + * @return a list of N - 1 variables, the list ( v_i ) from i = 1 to N - 1 + */ + std::vector<prop::SatLiteral> computePivotsForChain( + const std::vector<TraceCheckIdx>& chain) const; + + /** + * Write the LFSC identifier for the proof of a clause + * + * @param o where to write to + * @param i the TRACECHECK index for the clause whose proof identifier to + * print + */ + void writeIdForClauseProof(std::ostream& o, TraceCheckIdx i) const; + + // A list of the Ids for the input clauses, in order. + std::vector<ClauseId> d_inputClauseIds; + // A list of new variable definitions, in order. + std::vector<ErDefinition> d_definitions; + // The underlying TRACECHECK proof. + TraceCheckProof d_tracecheck; +}; + +} // namespace er +} // namespace proof +} // namespace CVC4 + +#endif // __CVC4__PROOF__ER__ER_PROOF_H |