From 76729f9670ba63a9146079b081bdb5b5ae0bbd3d Mon Sep 17 00:00:00 2001
From: Kenny Ballou <kballou@devnulllabs.io>
Date: Fri, 28 Feb 2020 15:36:09 -0700
Subject: CASA fork: initial commit

Snapshot from http://cse.unl.edu/~citportal/.
---
 casa/annealing/AnnealingFilter.H | 93 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 casa/annealing/AnnealingFilter.H

(limited to 'casa/annealing/AnnealingFilter.H')

diff --git a/casa/annealing/AnnealingFilter.H b/casa/annealing/AnnealingFilter.H
new file mode 100644
index 0000000..f787ae4
--- /dev/null
+++ b/casa/annealing/AnnealingFilter.H
@@ -0,0 +1,93 @@
+// Copyright 2008, 2009 Brady J. Garvin
+
+// This file is part of Covering Arrays by Simulated Annealing (CASA).
+
+// CASA is free software: you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// CASA is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with CASA.  If not, see <http://www.gnu.org/licenses/>.
+
+
+#ifndef ANNEALING_FILTER_H
+#define ANNEALING_FILTER_H
+
+#include <cassert>
+#include <iostream>
+
+#include "search/GreedyFilter.H"
+#include "events/Listener.H"
+
+// Decides, according to the rules of simulated annealing, when to take good
+// moves and when to take bad ones.
+
+// Should be added as a listener to search iterations in order that cooling be
+// synchronized with the search.
+
+template<class STATE, class COST>class AnnealingFilter :
+  public GreedyFilter<STATE,COST>,
+  public Listener<SearchIteration> {
+
+  typedef Heuristic<STATE,COST>		HeuristicT;
+  typedef Goal<STATE>			GoalT;
+
+  double				temperature;
+  const double				decay;
+
+public:
+  AnnealingFilter(double temperature, double decay) :
+    temperature(temperature),
+    decay(decay) {
+    assert(0 <= decay);
+    assert(decay <= 1);
+  }
+  virtual ~AnnealingFilter() {}
+
+  void setTemperature(double temperature) {
+    this->temperature = temperature;
+  }
+
+  virtual double convertToDelta(COST childEstimate, COST parentEstimate) const
+    = 0;
+
+  void signal(const SearchIteration&message) {
+    temperature *= decay;
+  }
+
+  void operator()
+    (std::set<STATE>&children,
+     const STATE&parent,
+     const HeuristicT&heuristic,
+     const GoalT&goal) const {
+    GreedyFilter<STATE,COST>::operator()(children, heuristic, goal);
+    assert(children.size() <= 1);
+    if (children.size()) {
+      typename std::set<STATE>::iterator child = children.begin();
+      COST childEstimate = heuristic.estimate(*child, goal);
+      COST parentEstimate = heuristic.estimate(parent, goal);
+      if (!(parentEstimate < childEstimate)) {
+	// Always take good moves.
+	return;
+      }
+      double delta = convertToDelta(childEstimate, parentEstimate);
+      double probability = exp(delta / temperature);
+      int boundary = (int)(probability * RAND_MAX);
+      if (rand() < boundary) {
+	// Sometimes take bad moves.
+	return;
+      }
+      children.clear();
+    }
+    // When no moves are possible or a bad move is rejected, keep the parent.
+    children.insert(parent);
+  }
+};
+
+#endif
-- 
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