"Christian Schulte" <[email protected]> writes:
> Sounds like a pretty good idea. I'll leave it to Guido as the master of set
> variables (he is away right now).
> [...]
>> From: Luca Di Gaspero <[email protected]>
>> [...]
>> would it be possible to have channeling constraints between SetVarArrays in
>> the new gecode version. Even though they are just implemented with
>> decomposition they would be extremely useful in modeling (and in teaching).
>> The constraints I am thinking about are of the form:
>>
>> i \in SetA_j \iff j \in SetB_i
Here you go:
Index: gecode/set.hh
===================================================================
--- gecode/set.hh (revision 12448)
+++ gecode/set.hh (working copy)
@@ -894,6 +894,10 @@
GECODE_SET_EXPORT void
channel(Home home, const BoolVarArgs& x, SetVar y);
+ /// Post propagator for \f$j\in x_i \Leftrightarrow i\in y_j\f$
+ GECODE_SET_EXPORT void
+ channel(Home home, const SetVarArgs& x, const SetVarArgs& y);
+
/// Post propagator for \f$ |s|=x \f$
GECODE_SET_EXPORT void
cardinality(Home home, SetVar s, IntVar x);
Index: gecode/set/int.cpp
===================================================================
--- gecode/set/int.cpp (revision 12448)
+++ gecode/set/int.cpp (working copy)
@@ -179,6 +179,19 @@
::post(home,xv,y)));
}
+ void
+ channel(Home home, const SetVarArgs& x, const SetVarArgs& y)
+ {
+ if (home.failed()) return;
+ ViewArray<Set::CachedView<Set::SetView> > xa(home, x.size());
+ for (int i=x.size(); i--;)
+ new (&xa[i]) Int::CachedView<Set::SetView>(x[i]);
+ ViewArray<Set::CachedView<Set::SetView> > ya(home, y.size());
+ for (int i=y.size(); i--;)
+ new (&ya[i]) Set::CachedView<Set::SetView>(y[i]);
+ GECODE_ES_FAIL((Set::Int::ChannelSet<Set::SetView>::post(home,xa,ya)));
+ }
+
void weights(Home home, IntSharedArray elements, IntSharedArray weights,
SetVar x, IntVar y) {
if (home.failed()) return;
Index: gecode/set/int/channel-int.hpp
===================================================================
--- gecode/set/int/channel-int.hpp (revision 12448)
+++ gecode/set/int/channel-int.hpp (working copy)
@@ -153,6 +153,136 @@
return (assigned==xs.size()) ? home.ES_SUBSUMED(*this) : ES_NOFIX;
}
+ template <typename View>
+ forceinline
+ ChannelSet<View>::ChannelSet(Home home,
+ ViewArray<CachedView<View> >& xs0,
+ ViewArray<CachedView<View> >& ys0)
+ : Propagator(home), xs(xs0), ys(ys0)
+ {
+ for (int i=xs.size(); i--;)
+ xs[i].initCache(home,IntSet::empty,IntSet(0,ys.size()-1));
+ for (int i=ys.size(); i--;)
+ ys[i].initCache(home,IntSet::empty,IntSet(0,xs.size()-1));
+ xs.subscribe(home,*this, PC_SET_ANY);
+ ys.subscribe(home,*this, PC_SET_ANY);
+ }
+
+ template <typename View>
+ forceinline
+ ChannelSet<View>::ChannelSet(Space& home, bool share, ChannelSet& p)
+ : Propagator(home, share, p)
+ {
+ xs.update(home, share, p.xs);
+ ys.update(home, share, p.ys);
+ }
+
+ template <typename View>
+ forceinline ExecStatus
+ ChannelSet<View>::post(Home home,
+ ViewArray<CachedView<View> >& xs,
+ ViewArray<CachedView<View> >& ys)
+ {
+ int xssize = xs.size();
+ for (int i=ys.size(); i--;)
+ {
+ GECODE_ME_CHECK(ys[i].exclude(home, xssize, Limits::max));
+ GECODE_ME_CHECK(ys[i].exclude(home, Limits::min, -1));
+ }
+ int yssize = ys.size();
+ for (int i=xs.size(); i--;)
+ {
+ GECODE_ME_CHECK(xs[i].exclude(home, yssize, Limits::max));
+ GECODE_ME_CHECK(xs[i].exclude(home, Limits::min, -1));
+ }
+ (void) new (home) ChannelSet(home,xs,ys);
+ return ES_OK;
+ }
+
+template <typename View>
+ PropCost
+ ChannelSet<View>::cost(const Space&, const ModEventDelta&) const
+ {
+ return PropCost::quadratic(PropCost::HI, xs.size()+ys.size());
+ }
+
+ template <typename View>
+ forceinline size_t
+ ChannelSet<View>::dispose(Space& home)
+ {
+ xs.cancel(home, *this, PC_SET_ANY);
+ ys.cancel(home, *this, PC_SET_ANY);
+ (void) Propagator::dispose(home);
+ return sizeof(*this);
+ }
+
+ template <typename View>
+ Actor*
+ ChannelSet<View>::copy(Space& home, bool share)
+ {
+ return new (home) ChannelSet(home,share,*this);
+ }
+
+ template <typename View>
+ ExecStatus
+ ChannelSet<View>::propagate(Space& home, const ModEventDelta&)
+ {
+ int assigned = 0;
+ bool again = true;
+ while (again)
+ {
+ assigned = 0;
+ again = false;
+ for (int i=xs.size(); i--;)
+ {
+ if (xs[i].assigned())
+ ++assigned;
+ if (xs[i].glbModified())
+ {
+ GlbDiffRanges<View> xilb(xs[i]);
+ Iter::Ranges::ToValues<GlbDiffRanges<View> > dv(xilb);
+ for (;dv();++dv)
+ GECODE_ME_CHECK(ys[dv.val()].include(home,i));
+ xs[i].cacheGlb(home);
+ again = true;
+ }
+ if (xs[i].lubModified())
+ {
+ LubDiffRanges<View> xiub(xs[i]);
+ Iter::Ranges::ToValues<LubDiffRanges<View> > dv(xiub);
+ for (;dv();++dv)
+ GECODE_ME_CHECK(ys[dv.val()].exclude(home,i));
+ xs[i].cacheLub(home);
+ again = true;
+ }
+ }
+ for (int i=ys.size(); i--;)
+ {
+ if (ys[i].assigned())
+ ++assigned;
+ if (ys[i].glbModified())
+ {
+ GlbDiffRanges<View> yilb(ys[i]);
+ Iter::Ranges::ToValues<GlbDiffRanges<View> > dv(yilb);
+ for (;dv();++dv)
+ GECODE_ME_CHECK(xs[dv.val()].include(home,i));
+ ys[i].cacheGlb(home);
+ again = true;
+ }
+ if (ys[i].lubModified())
+ {
+ LubDiffRanges<View> yiub(ys[i]);
+ Iter::Ranges::ToValues<LubDiffRanges<View> > dv(yiub);
+ for (;dv();++dv)
+ GECODE_ME_CHECK(xs[dv.val()].exclude(home,i));
+ ys[i].cacheLub(home);
+ again = true;
+ }
+ }
+ }
+
+ return (assigned == xs.size()+ys.size()) ? home.ES_SUBSUMED(*this) : ES_FIX;
+ }
}}}
// STATISTICS: set-prop
Index: gecode/set/int.hh
===================================================================
--- gecode/set/int.hh (revision 12448)
+++ gecode/set/int.hh (working copy)
@@ -406,6 +406,48 @@
};
/**
+ * \brief %Propagator for successors/predecessors channelling
+ *
+ * Implements channelling constraints between 2 sequences of SetVars.
+ * For SetVars \f$x_0,\dots,x_n\f$ and SetVars \f$y_0,\dots,y_m\f$ it
+ * propagates the constraint \f$j\in x_i \Leftrightarrow i\in y_i\f$.
+ * \f$x_i\f$ is the set of successors of \f$i\f$, and \f$y_j\f$ is the
+ * set of predecessors of \f$j\f$.
+ *
+ * Requires \code #include <gecode/set/int.hh> \endcode
+ * \ingroup FuncSetProp
+ */
+
+ template<typename View>
+ class ChannelSet: public Propagator {
+ protected:
+ /// SetViews, \f$x_i\f$ reflects the successors of \f$i\f$
+ ViewArray<CachedView<View> > xs;
+ /// SetViews, \f$y_j\f$ reflects the predecessors of \f$j\f$
+ ViewArray<CachedView<View> > ys;
+
+ /// Constructor for cloning \a p
+ ChannelSet(Space& home, bool share, ChannelSet& p);
+ /// Constructor for posting
+ ChannelSet(Home home,
+ ViewArray<CachedView<View> >&,
+ ViewArray<CachedView<View> >&);
+ public:
+ /// Copy propagator during cloning
+ virtual Actor* copy(Space& home, bool);
+ /// Cost function (defined as PC_QUADRATIC_HI)
+ virtual PropCost cost(const Space& home, const ModEventDelta& med) const;
+ /// Delete propagator and return its size
+ virtual size_t dispose(Space& home);
+ /// Perform propagation
+ virtual ExecStatus propagate(Space& home, const ModEventDelta& med);
+ /// Post propagator for \f$j\in x_i \Leftrightarrow i\in y_j\f$
+ static ExecStatus post(Home home,
+ ViewArray<CachedView<View> >& x,
+ ViewArray<CachedView<View> >& y);
+ };
+
+ /**
* \brief %Propagator for weight of a set
*
* Requires \code #include <gecode/set/int.hh> \endcode
Index: gecode/set/branch/post-view.cpp
===================================================================
--- gecode/set/branch/post-view.cpp (revision 12448)
+++ gecode/set/branch/post-view.cpp (working copy)
@@ -2,7 +2,7 @@
* CAUTION:
* This file has been automatically generated. Do not edit,
* edit the specification file
- * gecode/set/branch/post-view.bs
+ * ../gecode/set/branch/post-view.bs
* instead.
*
* This file contains generated code fragments which are
Cheers,
--Denys
PS: Guido, you might want to shuffle the code to different files. I just
wasn't sure where to put it.
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