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/********************* */
/*! \file lrat_proof.h
** \verbatim
** Top contributors (to current version):
** Alex Ozdemir, Mathias Preiner
** This file is part of the CVC4 project.
** Copyright (c) 2009-2020 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 LRAT Proof Format
**
** Declares C++ types that represent a LRAT proof.
** Defines serialization for these types.
**
** Represents an **abstract** LRAT proof.
** Does **not** represent an LFSC LRAT proof, or an LRAT proof being used to
** prove things about bit-vectors.
**
** Paper on LRAT: https://www.cs.utexas.edu/~marijn/publications/lrat.pdf
**/
#include "cvc4_private.h"
#ifndef CVC4__PROOF__LRAT__LRAT_PROOF_H
#define CVC4__PROOF__LRAT__LRAT_PROOF_H
#include <iosfwd>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
#include "proof/clause_id.h"
// Included because we need operator<< for the SAT types
#include "prop/sat_solver.h"
#include "util/statistics_registry.h"
namespace CVC4 {
namespace proof {
namespace lrat {
// Refers to clause position within an LRAT proof
using ClauseIdx = size_t;
// This is conceptually an Either<Addition,Deletion>
class LratInstruction
{
public:
/**
* Write this LRAT instruction in textual format
*
* @param out the stream to write to
*/
virtual void outputAsText(std::ostream& out) const = 0;
/**
* Write this LRAT instruction as an LFSC value
*
* @param out the stream to write to
* @param closeParen the stream to write any closing parentheses to
*
*/
virtual void outputAsLfsc(std::ostream& o,
std::ostream& closeParen) const = 0;
virtual ~LratInstruction() = default;
};
class LratDeletion : public LratInstruction
{
public:
LratDeletion(ClauseIdx idxOfClause, std::vector<ClauseIdx>&& clauses)
: d_idxOfClause(idxOfClause), d_clauses(clauses)
{
// Nothing left to do
}
LratDeletion() = default;
void outputAsText(std::ostream& out) const override;
void outputAsLfsc(std::ostream& o, std::ostream& closeParen) const override;
private:
// This idx doesn't really matter, but it's in the format anyway, so we parse
// it.
ClauseIdx d_idxOfClause;
// Clauses to delete
std::vector<ClauseIdx> d_clauses;
};
// A sequence of locations that will contain unit clauses during unit
// propegation
using LratUPTrace = std::vector<ClauseIdx>;
class LratAddition : public LratInstruction
{
public:
LratAddition(ClauseIdx idxOfClause,
prop::SatClause&& clause,
LratUPTrace&& atTrace,
std::vector<std::pair<ClauseIdx, LratUPTrace>> resolvants)
: d_idxOfClause(idxOfClause),
d_clause(clause),
d_atTrace(atTrace),
d_resolvants(resolvants)
{
// Nothing left to do
}
void outputAsText(std::ostream& out) const override;
void outputAsLfsc(std::ostream& o, std::ostream& closeParen) const override;
private:
// The idx for the new clause
ClauseIdx d_idxOfClause;
// The new clause
prop::SatClause d_clause;
// UP trace based on the negation of that clause
LratUPTrace d_atTrace;
// Clauses that can resolve with `clause` on its first variable,
// together with a UP trace after that resolution.
// Used for RAT checks.
std::vector<std::pair<ClauseIdx, LratUPTrace>> d_resolvants;
};
class LratProof
{
public:
/**
* @brief Construct an LRAT proof from a DRAT proof, using drat-trim
*
* @param clauses A store of clauses that might be in our formula
* @param usedIds the ids of clauses that are actually in our formula
* @param dratBinary The DRAT proof from the SAT solver, as a binary stream.
*
* @return an LRAT proof an a timer for how long it took to run drat-trim
*/
static LratProof fromDratProof(
const std::unordered_map<ClauseId, prop::SatClause>& clauses,
const std::vector<ClauseId> usedIds,
const std::string& dratBinary,
TimerStat& toolTimer);
/**
* @brief Construct an LRAT proof from its textual representation
*
* @param textualProof the textual encoding of the LRAT proof. See the paper
* in the file's header comment.
*/
LratProof(std::istream& textualProof);
/**
* Construct a LRAT proof from an explicit instruction list
*
* @param instructions
*/
LratProof(std::vector<std::unique_ptr<LratInstruction>>&& instructions)
: d_instructions(std::move(instructions))
{
// Nothing else
}
const std::vector<std::unique_ptr<LratInstruction>>& getInstructions() const
{
return d_instructions;
}
void outputAsLfsc(std::ostream& o) const;
private:
// The instructions in the proof. Each is a deletion or addition.
std::vector<std::unique_ptr<LratInstruction>> d_instructions;
};
// Prints the LRAT proof in textual format
std::ostream& operator<<(std::ostream& o, const LratProof& p);
std::ostream& operator<<(std::ostream& o, const LratInstruction& i);
} // namespace lrat
} // namespace proof
} // namespace CVC4
#endif
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