Added relaxation abstraction for LNS

git-svn-id: file:///Volumes/GecodeGitMigration/gecode-svn-mirror/gecode/trunk@15218 e85b7adc-8362-4630-8c63-7469d557c915

Author: Christian Schulte

Makefile.dep

@@ -267,7 +267,8 @@ SEARCHHDR0 = \
 	meta/rbs.hh meta/rbs.hpp meta/nogoods.hh meta/dead.hh \
 	meta/sequential/pbs.hh meta/parallel/pbs.hh \
 	meta/sequential/pbs.hpp meta/parallel/pbs.hpp \
-	dfs.hpp bab.hpp lds.hpp rbs.hpp pbs.hpp
+	dfs.hpp bab.hpp lds.hpp rbs.hpp pbs.hpp \
+	relax.hh
 
 SEARCHSRC	= $(SEARCHSRC0:%=gecode/search/%.cpp)
 SEARCHHDR	= gecode/search.hh $(SEARCHHDR0:%=gecode/search/%)
@@ -328,6 +329,7 @@ INTSRC0 = \
 	arithmetic/mult.cpp  \
 	branch/view-sel.cpp branch/val-sel-commit.cpp \
 	branch/view-values.cpp \
+	relax.cpp \
 	ldsb.cpp ldsb/sym-imp.cpp ldsb/sym-obj.cpp \
 	trace.cpp trace/tracer.cpp \
 	exception.cpp
@@ -465,6 +467,7 @@ FLOATSRC0 = \
 	var/float.cpp arithmetic.cpp array.cpp branch.cpp rel.cpp linear.cpp \
 	linear/post.cpp branch/activity.cpp rounding.cpp exec.cpp \
 	branch/val-sel-commit.cpp branch/view-sel.cpp dom.cpp \
+	relax.cpp \
 	trace.cpp trace/tracer.cpp \
 	exception.cpp
 
@@ -545,6 +548,7 @@ SETSRC0 =								 \
 	exec.cpp branch/activity.cpp branch/view-sel.cpp \
 	branch/val-sel-commit.cpp  branch/ngl.cpp \
 	ldsb.cpp ldsb/sym-imp.cpp \
+	relax.cpp \
 	trace.cpp trace/tracer.cpp \
 	exception.cpp
 SETHDR0 =								     \

Makefile.in

@@ -72,6 +72,38 @@ Date: 2015-?-?
 [DESCRIPTION]
 Gaga
 
+[ENTRY]
+Module: float
+What:   new
+Rank:   minor
+[DESCRIPTION]
+Added relax() function for relaxed assignment of float variables
+from a previous solution, see MPG for details.
+
+[ENTRY]
+Module: set
+What:   new
+Rank:   minor
+[DESCRIPTION]
+Added relax() function for relaxed assignment of set variables
+from a previous solution, see MPG for details.
+
+[ENTRY]
+Module: int
+What:   new
+Rank:   minor
+[DESCRIPTION]
+Added relax() function for relaxed assignment of integer and
+Boolean variables from a previous solution, see MPG for details.
+
+[ENTRY]
+Module: driver
+What:   new
+Rank:   minor
+[DESCRIPTION]
+The probability for relaxing variables in LNS can be passed with
+the -relax commandline option.
+
 [ENTRY]
 Module: int
 What:   bug

changelog.in

@@ -41,6 +41,7 @@
 
 using namespace Gecode;
 
+
 /// Specifications for the photo example
 class PhotoSpec {
 public:
@@ -82,10 +83,13 @@ class Photo : public IntMinimizeScript {
   /// Photo specification
   const PhotoSpec& spec;
   /// Person's position on photo
-  IntVarArray      pos;
+  IntVarArray pos;
   /// Number of violated preferences
-  IntVar           violations;
-
+  IntVar violations;
+  /// Random number generator for LNS
+  Rnd rnd;
+  /// Relaxation probability
+  double p;
 public:
   /// Branching to use for model
   enum {
@@ -97,7 +101,8 @@ class Photo : public IntMinimizeScript {
     IntMinimizeScript(opt),
     spec(opt.size() == 0 ? p_small : p_large),
     pos(*this,spec.n_names, 0, spec.n_names-1),
-    violations(*this,0,spec.n_prefs)
+    violations(*this,0,spec.n_prefs),
+    rnd(opt.seed()), p(opt.relax())
   {
     // Map preferences to violation
     BoolVarArgs viol(spec.n_prefs);
@@ -120,10 +125,20 @@ class Photo : public IntMinimizeScript {
              INT_VAL_MIN());
     }
   }
-
+  /// Slave function for restarts
+  bool slave(const MetaInfo& mi) {
+    if ((mi.type() == MetaInfo::RESTART) &&
+        (mi.restart() > 0) && (p > 0.0)) {
+      const Photo& l = static_cast<const Photo&>(*mi.last());
+      relax(*this, pos, l.pos, rnd, p);
+      return false;
+    } else {
+      return true;
+    }
+  }
   /// Constructor for cloning \a s
   Photo(bool share, Photo& s) :
-    IntMinimizeScript(share,s), spec(s.spec) {
+    IntMinimizeScript(share,s), spec(s.spec), rnd(s.rnd), p(s.p) {
     pos.update(*this, share, s.pos);
     violations.update(*this, share, s.violations);
   }
@@ -154,6 +169,7 @@ main(int argc, char* argv[]) {
   opt.size(1);
   opt.iterations(10);
   opt.ipl(IPL_BND);
+  opt.relax(0.7);
   opt.branching(Photo::BRANCH_DEGREE);
   opt.branching(Photo::BRANCH_NONE,   "none");
   opt.branching(Photo::BRANCH_DEGREE, "degree");
@@ -162,6 +178,5 @@ main(int argc, char* argv[]) {
   return 0;
 }
 
-
 // STATISTICS: example-any
 

examples/photo.cpp

@@ -395,6 +395,7 @@ namespace Gecode {
     Driver::UnsignedIntOption _r_scale;       ///< Restart scale factor
     Driver::BoolOption        _nogoods;       ///< Whether to use no-goods
     Driver::UnsignedIntOption _nogoods_limit; ///< Limit for no-good extraction
+    Driver::DoubleOption      _relax;         ///< Probability to relax variable
     Driver::BoolOption        _interrupt;     ///< Whether to catch SIGINT
     //@}
 
@@ -548,6 +549,11 @@ namespace Gecode {
     /// Return depth limit for nogoods
     unsigned int nogoods_limit(void) const;
 
+    /// Set default relax probability
+    void relax(double d);
+    /// Return default relax probability
+    double relax(void) const;
+
     /// Set default interrupt behavior
     void interrupt(bool b);
     /// Return interrupt behavior

gecode/driver.hh

@@ -533,6 +533,7 @@ namespace Gecode {
       _nogoods("-nogoods","whether to use no-goods from restarts",false),
       _nogoods_limit("-nogoods-limit","depth limit for no-good extraction",
                      Search::Config::nogoods_limit),
+      _relax("-relax","probability for relaxing variable", 0.0),
       _interrupt("-interrupt","whether to catch Ctrl-C (true) or not (false)",
                  true),
 
@@ -568,6 +569,7 @@ namespace Gecode {
     add(_assets); add(_slice);
     add(_restart); add(_r_base); add(_r_scale);
     add(_nogoods); add(_nogoods_limit);
+    add(_relax);
     add(_mode); add(_iterations); add(_samples); add(_print_last);
     add(_out_file); add(_log_file); add(_trace);
   }

gecode/driver/options.cpp

@@ -418,6 +418,15 @@ namespace Gecode {
     return _nogoods_limit.value();
   }
 
+  inline void
+  Options::relax(double d) {
+    _relax.value(d);
+  }
+  inline double
+  Options::relax(void) const {
+    return _relax.value();
+  }
+
 
 
   inline void

gecode/driver/options.hpp

@@ -1814,6 +1814,34 @@ namespace Gecode {
 
 }
 
+namespace Gecode {
+
+  /*
+   * \brief Relaxed assignment of variables in \a x from values in \a sx
+   *
+   * The variables in \a x are assigned values from the assigned variables
+   * in the solution \a sx with a relaxation probability \a p. That is, 
+   * if \$fp=0.1\f$ approximately 10% of the variables in \a x will be 
+   * assigned a value from \a sx.
+   *
+   * The random numbers are generated from the generator \a r. At least
+   * one variable will not be assigned: in case the relaxation attempt 
+   * would suggest that all variables should be assigned, a single
+   * variable will be selected randomly to remain unassigned.
+   *
+   * Throws an exception of type Float::ArgumentSizeMismatch, if \a x and
+   * \a sx are of different size.
+   *
+   * Throws an exception of type Float::OutOfLimits, if \a p is not between
+   * \a 0.0 and \a 1.0.
+   *
+   * \ingroup TaskModeFloat
+   */
+  GECODE_FLOAT_EXPORT void 
+  relax(Home home, const FloatVarArgs& x, const FloatVarArgs& sx,
+        Rnd r, double p);
+
+}
 
 #include <gecode/float/trace/trace-view.hpp>
 

gecode/float.hh

@@ -0,0 +1,74 @@
+/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
+/*
+ *  Main authors:
+ *     Christian Schulte <schulte@gecode.org>
+ *
+ *  Copyright:
+ *     Christian Schulte, 2016
+ *
+ *  Last modified:
+ *     $Date$ by $Author$
+ *     $Revision$
+ *
+ *  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.
+ *
+ */
+
+#include <gecode/float.hh>
+#include <gecode/search/relax.hh>
+
+namespace Gecode { namespace Float {
+
+  /// Class for posting equalities for non-relaxed variables
+  class Relax {
+  public:
+    /// Post the actual equality for non-relaxed variables
+    ExecStatus operator ()(Home home, FloatVar x, FloatVar sx);
+  };
+
+  forceinline ExecStatus
+  Relax::operator ()(Home home, FloatVar x, FloatVar sx) {
+    FloatView xv(x);
+    return me_failed(xv.eq(home,sx.val())) ? ES_FAILED : ES_OK;
+  }
+
+}}
+
+namespace Gecode {
+
+  void 
+  relax(Home home, const FloatVarArgs& x, const FloatVarArgs& sx,
+        Rnd r, double p) {
+    if (x.size() != sx.size())
+      throw Float::ArgumentSizeMismatch("Float::relax");
+    if ((p < 0.0) || (p > 1.0))
+      throw Float::OutOfLimits("Float::relax");
+    Float::Relax fr;
+    Search::relax<FloatVarArgs,Float::Relax>(home,x,sx,r,p,fr);
+  }
+
+}
+
+// STATISTICS: float-other
+

gecode/float/relax.cpp

@@ -55,6 +55,7 @@
 #include <vector>
 
 #include <gecode/kernel.hh>
+#include <gecode/search.hh>
 #include <gecode/iter.hh>
 
 /*
@@ -4579,6 +4580,61 @@ namespace Gecode {
          BoolBranchFilter bf=NULL, BoolVarValPrint vvp=NULL);
 }
 
+namespace Gecode {
+
+  /*
+   * \brief Relaxed assignment of variables in \a x from values in \a sx
+   *
+   * The variables in \a x are assigned values from the assigned variables
+   * in the solution \a sx with a relaxation probability \a p. That is, 
+   * if \$fp=0.1\f$ approximately 10% of the variables in \a x will be 
+   * assigned a value from \a sx.
+   *
+   * The random numbers are generated from the generator \a r. At least
+   * one variable will not be assigned: in case the relaxation attempt 
+   * would suggest that all variables should be assigned, a single
+   * variable will be selected randomly to remain unassigned.
+   *
+   * Throws an exception of type Int::ArgumentSizeMismatch, if \a x and
+   * \a sx are of different size.
+   *
+   * Throws an exception of type Int::OutOfLimits, if \a p is not between
+   * \a 0.0 and \a 1.0.
+   *
+   * \ingroup TaskModelInt
+   */
+  GECODE_INT_EXPORT void 
+  relax(Home home, const IntVarArgs& x, const IntVarArgs& sx,
+        Rnd r, double p);
+
+  /*
+   * \brief Relaxed assignment of variables in \a x from values in \a sx
+   *
+   * The variables in \a x are assigned values from the assigned variables
+   * in the solution \a sx with a relaxation probability \a p. That is, 
+   * if \$fp=0.1\f$ approximately 10% of the variables in \a x will be 
+   * assigned a value from \a sx.
+   *
+   * The random numbers are generated from the generator \a r. At least
+   * one variable will not be assigned: in case the relaxation attempt 
+   * would suggest that all variables should be assigned, a single
+   * variable will be selected randomly to remain unassigned.
+   *
+   * Throws an exception of type Int::ArgumentSizeMismatch, if \a x and
+   * \a sx are of different size.
+   *
+   * Throws an exception of type Int::OutOfLimits, if \a p is not between
+   * \a 0.0 and \a 1.0.
+   *
+   * \ingroup TaskModelInt
+   */
+  GECODE_INT_EXPORT void
+  relax(Home home, const BoolVarArgs& x, const BoolVarArgs& sx,
+        Rnd r, double p);
+
+}
+
+
 #include <gecode/int/trace/int-trace-view.hpp>
 #include <gecode/int/trace/bool-trace-view.hpp>