/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */ /* * Main authors: * Christian Schulte * Guido Tack * * Contributing authors: * Gabor Szokoli * * Copyright: * Christian Schulte, 2002 * Guido Tack, 2004 * Gabor Szokoli, 2003 * * Last modified: * $Date: 2008-07-11 09:28:48 +0200 (Fri, 11 Jul 2008) $ by $Author: tack $ * $Revision: 7285 $ * * This file is part of Gecode, the generic constraint * development environment: * http://www.gecode.org * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. * */ #ifndef __GECODE_INT_DISTINCT_HH__ #define __GECODE_INT_DISTINCT_HH__ #include "gecode/int.hh" #include "gecode/int/rel.hh" /** * \namespace Gecode::Int::Distinct * \brief %Distinct propagators */ namespace Gecode { namespace Int { namespace Distinct { /** * \brief Naive value distinct propagator * * Eliminates values of assigned views of type \a View. * * Requires \code #include "gecode/int/distinct.hh" \endcode * \ingroup FuncIntProp */ template class Val : public NaryPropagator { protected: using NaryPropagator::x; /// Constructor for posting Val(Space* home, ViewArray& x); /// Constructor for cloning \a p Val(Space* home, bool share, Val& p); public: /// Copy propagator during cloning virtual Actor* copy(Space* home, bool share); /// Perform propagation virtual ExecStatus propagate(Space* home, ModEventDelta med); /// Specification for this propagator virtual Reflection::ActorSpec spec(const Space* home, Reflection::VarMap& m) const; /// Name of this propagator static Support::Symbol ati(void); /// Post propagator for specification static void post(Space* home, Reflection::VarMap& vars, const Reflection::ActorSpec& spec); /// Post propagator for view array \a x static ExecStatus post(Space* home, ViewArray& x); }; /** * \brief Eliminate singletons by naive value propagation * * This is actually the propagation algorithm for Distinct::Val. * It is available as separate function as it is reused for * both bounds consistent and domain consistent distinct * propagators. * * If \a complete is true, computes fixpoint, otherwise might not * compute fixpoint. This can be helpful when used together with * bounds or domain propagation to protect from pathological cases * which can be handled more efficiently with bounds propagation. */ template ExecStatus prop_val(Space* home, ViewArray&); /** * \brief Bounds consistent distinct propagator * * The propagator uses staging: first it uses naive value-based * propagation and only then uses bounds consistent propagation. * Due to using naive value-based propagation, the propagator * might actually achieve stronger consistency than just * bounds consistency. * * The algorithm is taken from: * A. Lopez-Ortiz, C.-G. Quimper, J. Tromp, and P. van Beek. * A fast and simple algorithm for bounds consistency of the * alldifferent constraint. IJCAI-2003. * * This implementation uses the code that is provided by * Peter Van Beek: * http://ai.uwaterloo.ca/~vanbeek/software/software.html * The code (originally by John Tromp) here has only been slightly modified * to fit %Gecode (taking idempotent/non-idempotent propagation into account) * and uses a more efficient layout of datastructures (keeping the number * of different arrays small). * * Requires \code #include "gecode/int/distinct.hh" \endcode * \ingroup FuncIntProp */ template class Bnd : public Propagator { protected: /// Views on which to perform bounds-propagation ViewArray x; /// Views on which to perform value-propagation (subset of \c x) ViewArray y; /// Constructor for posting Bnd(Space* home, ViewArray& x); /// Constructor for cloning \a p Bnd(Space* home, bool share, Bnd& p); public: /// Post propagator for view array \a x static ExecStatus post(Space* home, ViewArray& x); /// Post propagator for specification static void post(Space* home, Reflection::VarMap& vars, const Reflection::ActorSpec& spec); /// Perform propagation virtual ExecStatus propagate(Space* home, ModEventDelta med); /** * \brief Cost function * * If in stage for naive value propagation, the cost is dynamic * PC_LINEAR_LO. Otherwise it is dynamic PC_LINEAR_HI. */ virtual PropCost cost(ModEventDelta med) const; /// Copy propagator during cloning virtual Actor* copy(Space* home, bool share); /// Destructor virtual size_t dispose(Space* home); /// Specification for this propagator virtual Reflection::ActorSpec spec(const Space* home, Reflection::VarMap& m) const; /// Name of this propagator static Support::Symbol ati(void); }; /** * \brief Perform bounds consistent distinct propagation * * This is actually the propagation algorithm for Distinct::Bnd. * It is available as separate function as it is reused for * both bounds consistent and domain consistent distinct * propagators. */ template ExecStatus prop_bnd(Space* home, ViewArray& x, int m); template class ViewNode; template class ValNode; /** * \brief Propagation controller for domain consistent distinct * * The propagation controller provides convenient access to * performing incremental domain consistent distinct propagation * so that the routines can be reused easily. * * Requires \code #include "gecode/int/distinct.hh" \endcode * \ingroup FuncIntProp */ template class DomCtrl { protected: /// View-value graph for propagation class ViewValGraph { public: /// Array of view nodes ViewNode** view; /// Number of view nodes int n_view; /// Array of value nodes ValNode* val; /// Number of value nodes int n_val; /// Marking counter unsigned int count; public: /// Construct graph as not yet initialized ViewValGraph(void); /// Test whether graph has been initialized bool initialized(void) const; /// Initialize graph ExecStatus init(Space* home, int n, View* x); /// Mark edges in graph void mark(void); /// Prune unmarked edges, \a assigned is true if a view got assigned ExecStatus tell(Space* home, bool& assigned); /// Purge graph if necessary void purge(void); /// Synchronize graph with new view domains bool sync(void); public: /// Stack used during matching typedef Support::SentinelStack*> MatchStack; /// Find a matching for node \a x bool match(MatchStack& m, ViewNode* x); }; /// Propagation is performed on a view-value graph ViewValGraph vvg; public: /// Initialize with non-initialized view-value graph DomCtrl(void); /// Check whether a view-value graph is available bool available(void); /// Initialize view-value graph for views \a x ExecStatus init(Space* home, int n, View* x); /// Synchronize available view-value graph ExecStatus sync(void); /// Perform propagation, \a assigned is true if a view gets assigned ExecStatus propagate(Space* home, bool& assigned); }; /** * \brief Domain consistent distinct propagator * * The propagator uses staging: first it uses naive value-based * propagation and only then uses domain consistent propagation. * * The algorithm is taken from: * Jean-Charles Régin, A filtering algorithm for constraints * of difference in CSPs, Proceedings of the Twelfth National * Conference on Artificial Intelligence, pages 362--367. * Seattle, WA, USA, 1994. * * Requires \code #include "gecode/int/distinct.hh" \endcode * \ingroup FuncIntProp */ template class Dom : public NaryPropagator { protected: using NaryPropagator::x; /// Propagation controller DomCtrl dc; /// Constructor for cloning \a p Dom(Space* home, bool share, Dom& p); /// Constructor for posting Dom(Space* home, ViewArray& x); public: /// Perform propagation virtual ExecStatus propagate(Space* home, ModEventDelta med); /** * \brief Cost function * * If in stage for naive value propagation, the cost is dynamic * PC_LINEAR_LO. Otherwise it is dynamic PC_CUBIC_LO. */ virtual PropCost cost(ModEventDelta med) const; /// Copy propagator during cloning virtual Actor* copy(Space* home, bool share); /// Specification for this propagator virtual Reflection::ActorSpec spec(const Space* home, Reflection::VarMap& m) const; /// Name of this propagator static Support::Symbol ati(void); /// Post propagator for views \a x static ExecStatus post(Space* home, ViewArray& x); /// Post propagator for specification static void post(Space* home, Reflection::VarMap& vars, const Reflection::ActorSpec& spec); }; /** * \brief Ternary domain consistent distinct propagator * * Requires \code #include "gecode/int/distinct.hh" \endcode * \ingroup FuncIntProp */ template class TerDom : public TernaryPropagator { protected: using TernaryPropagator::x0; using TernaryPropagator::x1; using TernaryPropagator::x2; /// Constructor for cloning \a p TerDom(Space* home, bool share, TerDom& p); /// Constructor for posting TerDom(Space* home, View x0, View x1, View x2); public: /// Perform propagation virtual ExecStatus propagate(Space* home, ModEventDelta med); /// Copy propagator during cloning virtual Actor* copy(Space* home, bool share); /// Specification for this propagator virtual Reflection::ActorSpec spec(const Space* home, Reflection::VarMap& m) const; /// Name of this propagator static Support::Symbol ati(void); /// Post propagator for views \a x static ExecStatus post(Space* home, View x0, View x1, View x2); /// Post propagator for specification static void post(Space* home, Reflection::VarMap& vars, const Reflection::ActorSpec& spec); }; }}} #include "gecode/int/distinct/val.icc" #include "gecode/int/distinct/bnd.icc" #include "gecode/int/distinct/ter-dom.icc" #include "gecode/int/distinct/dom.icc" #endif // STATISTICS: int-prop