diff options
author | Tim King <taking@cs.nyu.edu> | 2013-05-03 20:53:25 -0400 |
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committer | Tim King <taking@cs.nyu.edu> | 2013-05-03 20:53:25 -0400 |
commit | 5a20ba9f1f843fe066bbc8268f511a71902b88cb (patch) | |
tree | 222810c4451bb0c2385a4e499480fc99f342a313 /src/theory/arith/attempt_solution_simplex.h | |
parent | 9a490befefedfd40b7abab5080e84fb7c0540f86 (diff) |
Adding a smarter technique for pivoting in solutions for glpk.
Diffstat (limited to 'src/theory/arith/attempt_solution_simplex.h')
-rw-r--r-- | src/theory/arith/attempt_solution_simplex.h | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/src/theory/arith/attempt_solution_simplex.h b/src/theory/arith/attempt_solution_simplex.h new file mode 100644 index 000000000..5bcdc6aab --- /dev/null +++ b/src/theory/arith/attempt_solution_simplex.h @@ -0,0 +1,97 @@ +/********************* */ +/*! \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 "util/statistics_registry.h" +#include "theory/arith/simplex.h" +#include "theory/arith/approx_simplex.h" + +namespace CVC4 { +namespace theory { +namespace arith { + +class AttemptSolutionSDP : public SimplexDecisionProcedure { +public: + AttemptSolutionSDP(LinearEqualityModule& linEq, ErrorSet& errors, RaiseConflict conflictChannel, TempVarMalloc tvmalloc); + + Result::Sat attempt(const ApproximateSimplex::Solution& sol); + + Result::Sat findModel(bool exactResult){ + Unreachable(); + } + +private: + bool matchesNewValue(const DenseMap<DeltaRational>& nv, ArithVar v) const; + + bool processSignals(){ + TimerStat &timer = d_statistics.d_queueTime; + IntStat& conflictStat = d_statistics.d_conflicts; + return standardProcessSignals(timer, conflictStat); + } + /** These fields are designed to be accessible to TheoryArith methods. */ + class Statistics { + public: + TimerStat d_searchTime; + TimerStat d_queueTime; + IntStat d_conflicts; + + Statistics(); + ~Statistics(); + } d_statistics; +};/* class AttemptSolutionSDP */ + +}/* CVC4::theory::arith namespace */ +}/* CVC4::theory namespace */ +}/* CVC4 namespace */ + |