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Diffstat (limited to 'src/theory/arith/pure_update_simplex.h')
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diff --git a/src/theory/arith/pure_update_simplex.h b/src/theory/arith/pure_update_simplex.h new file mode 100644 index 000000000..50b751d7b --- /dev/null +++ b/src/theory/arith/pure_update_simplex.h @@ -0,0 +1,118 @@ +/********************* */ +/*! \file simplex.h + ** \verbatim + ** Original author: taking + ** Major contributors: none + ** Minor contributors (to current version): kshitij, mdeters + ** This file is part of the CVC4 prototype. + ** Copyright (c) 2009-2012 New York University and The University of Iowa + ** See the file COPYING in the top-level source directory for licensing + ** information.\endverbatim + ** + ** \brief This is an implementation of the Simplex Module for the Simplex for DPLL(T) + ** decision procedure. + ** + ** This implements the Simplex module for the Simpelx for DPLL(T) decision procedure. + ** See the Simplex for DPLL(T) technical report for more background.(citation?) + ** This shares with the theory a Tableau, and a PartialModel that: + ** - satisfies the equalities in the Tableau, and + ** - the assignment for the non-basic variables satisfies their bounds. + ** This is required to either produce a conflict or satisifying PartialModel. + ** Further, we require being told when a basic variable updates its value. + ** + ** During the Simplex search we maintain a queue of variables. + ** The queue is required to contain all of the basic variables that voilate their bounds. + ** As elimination from the queue is more efficient to be done lazily, + ** we do not maintain that the queue of variables needs to be only basic variables or only + ** variables that satisfy their bounds. + ** + ** The simplex procedure roughly follows Alberto's thesis. (citation?) + ** There is one round of selecting using a heuristic pivoting rule. (See PreferenceFunction + ** Documentation for the available options.) + ** The non-basic variable is the one that appears in the fewest pivots. (Bruno says that + ** Leonardo invented this first.) + ** After this, Bland's pivot rule is invoked. + ** + ** During this proccess, we periodically inspect the queue of variables to + ** 1) remove now extraneous extries, + ** 2) detect conflicts that are "waiting" on the queue but may not be detected by the + ** current queue heuristics, and + ** 3) detect multiple conflicts. + ** + ** Conflicts are greedily slackened to use the weakest bounds that still produce the + ** conflict. + ** + ** Extra things tracked atm: (Subject to change at Tim's whims) + ** - A superset of all of the newly pivoted variables. + ** - A queue of additional conflicts that were discovered by Simplex. + ** These are theory valid and are currently turned into lemmas + **/ + + +#include "cvc4_private.h" + +#pragma once + +#include "theory/arith/simplex.h" +#include "util/dense_map.h" +#include "util/statistics_registry.h" +#include <stdint.h> +#include "theory/arith/arithvar.h" +#include "theory/arith/delta_rational.h" + +namespace CVC4 { +namespace theory { +namespace arith { + +class PureUpdateSimplexDecisionProcedure : public SimplexDecisionProcedure{ +public: + PureUpdateSimplexDecisionProcedure(LinearEqualityModule& linEq, ErrorSet& errors, RaiseConflict conflictChannel, TempVarMalloc tvmalloc); + + Result::Sat findModel(bool exactResult); + +private: + ArithVar d_focusErrorVar; + + bool attemptPureUpdates(); + + /** + * This is the main simplex for DPLL(T) loop. + * It runs for at most maxIterations. + * + * Returns true iff it has found a conflict. + * d_conflictVariable will be set and the conflict for this row is reported. + */ + bool searchForFeasibleSolution(uint32_t maxIterations); + + bool processSignals(){ + TimerStat &timer = d_statistics.d_processSignalsTime; + IntStat& conflictStat = d_statistics.d_foundConflicts; + return standardProcessSignals(timer, conflictStat); + } + + /** These fields are designed to be accessible to TheoryArith methods. */ + class Statistics { + public: + IntStat d_pureUpdateFoundUnsat; + IntStat d_pureUpdateFoundSat; + IntStat d_pureUpdateMissed; + IntStat d_pureUpdates; + IntStat d_pureUpdateDropped; + IntStat d_pureUpdateConflicts; + + IntStat d_foundConflicts; + + TimerStat d_attemptPureUpdatesTimer; + TimerStat d_processSignalsTime; + + TimerStat d_constructionTimer; + + Statistics(); + ~Statistics(); + } d_statistics; +};/* class PureUpdateSimplexDecisionProcedure */ + +}/* CVC4::theory::arith namespace */ +}/* CVC4::theory namespace */ +}/* CVC4 namespace */ + |