52 lines
1.9 KiB
Java
52 lines
1.9 KiB
Java
// Copyright 2010-2022 Google LLC
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package com.google.ortools.sat.samples;
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import com.google.ortools.Loader;
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import com.google.ortools.sat.BoolVar;
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import com.google.ortools.sat.CpModel;
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import com.google.ortools.sat.Literal;
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/**
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* Reification is the action of associating a Boolean variable to a constraint. This boolean
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* enforces or prohibits the constraint according to the value the Boolean variable is fixed to.
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*
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* <p>Half-reification is defined as a simple implication: If the Boolean variable is true, then the
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* constraint holds, instead of an complete equivalence.
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*
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* <p>The SAT solver offers half-reification. To implement full reification, two half-reified
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* constraints must be used.
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*/
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public class ReifiedSampleSat {
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public static void main(String[] args) throws Exception {
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Loader.loadNativeLibraries();
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CpModel model = new CpModel();
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BoolVar x = model.newBoolVar("x");
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BoolVar y = model.newBoolVar("y");
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BoolVar b = model.newBoolVar("b");
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// Version 1: a half-reified boolean and.
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model.addBoolAnd(new Literal[] {x, y.not()}).onlyEnforceIf(b);
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// Version 2: implications.
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model.addImplication(b, x);
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model.addImplication(b, y.not());
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// Version 3: boolean or.
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model.addBoolOr(new Literal[] {b.not(), x});
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model.addBoolOr(new Literal[] {b.not(), y.not()});
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}
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}
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