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A collection of equivalence oracles
/* Copyright (C) 2013-2018 TU Dortmund
* This file is part of LearnLib, http://www.learnlib.de/.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package de.learnlib.oracle.equivalence;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Random;
import java.util.stream.Stream;
import de.learnlib.api.oracle.MembershipOracle;
import net.automatalib.automata.UniversalDeterministicAutomaton;
import net.automatalib.automata.concepts.Output;
import net.automatalib.automata.fsa.DFA;
import net.automatalib.automata.transout.MealyMachine;
import net.automatalib.util.automata.Automata;
import net.automatalib.util.automata.cover.Covers;
import net.automatalib.words.Word;
import net.automatalib.words.WordBuilder;
/**
* Implements an equivalence test by applying the W-method test on the given hypothesis automaton. Generally the
* Wp-method performs better in finding counter examples. Instead of enumerating the test suite in order, this is a
* sampling implementation: 1. sample uniformly from the states for a prefix 2. sample geometrically a random word 3.
* sample a word from the set of suffixes / state identifiers There are two parameters: minimalSize determines the
* minimal size of the random word, this is useful when one first performs a W(p)-method with some depth and continue
* with this randomized tester from that depth onward. The second parameter rndLength determines the expected length of
* the random word. (The expected length in effect is minimalSize + rndLength.) In the unbounded case it will not
* terminate for a correct hypothesis.
*
* @param
* automaton type
* @param
* input symbol type
* @param
* output domain type
*
* @author Joshua Moerman
*/
public class RandomWMethodEQOracle & Output, I, D>
extends AbstractTestWordEQOracle {
private final int minimalSize;
private final int rndLength;
private final int bound;
private final Random rand;
/**
* Constructor for an unbounded testing oracle.
*
* @param sulOracle
* oracle which answers tests.
* @param minimalSize
* minimal size of the random word
* @param rndLength
* expected length (in addition to minimalSize) of random word
*/
public RandomWMethodEQOracle(MembershipOracle sulOracle, int minimalSize, int rndLength) {
this(sulOracle, minimalSize, rndLength, 0);
}
/**
* Constructor for a bounded testing oracle.
*
* @param sulOracle
* oracle which answers tests.
* @param minimalSize
* minimal size of the random word
* @param rndLength
* expected length (in addition to minimalSize) of random word
* @param bound
* specifies the bound (set to 0 for unbounded).
*/
public RandomWMethodEQOracle(MembershipOracle sulOracle,
int minimalSize,
int rndLength,
int bound) {
this(sulOracle, minimalSize, rndLength, bound, new Random(), 1);
}
/**
* Constructor for a bounded testing oracle with a specific batch size.
*
* @param sulOracle
* oracle which answers tests.
* @param minimalSize
* minimal size of the random word
* @param rndLength
* expected length (in addition to minimalSize) of random word
* @param bound
* specifies the bound (set to 0 for unbounded).
* @param batchSize
* size of the batches sent to the membership oracle
*/
public RandomWMethodEQOracle(MembershipOracle sulOracle,
int minimalSize,
int rndLength,
int bound,
int batchSize) {
this(sulOracle, minimalSize, rndLength, bound, new Random(), batchSize);
}
/**
* Constructor for a bounded testing oracle with a specific batch size.
*
* @param sulOracle
* oracle which answers tests.
* @param minimalSize
* minimal size of the random word
* @param rndLength
* expected length (in addition to minimalSize) of random word
* @param bound
* specifies the bound (set to 0 for unbounded).
* @param random
* custom Random generator.
* @param batchSize
* size of the batches sent to the membership oracle
*/
public RandomWMethodEQOracle(MembershipOracle sulOracle,
int minimalSize,
int rndLength,
int bound,
Random random,
int batchSize) {
super(sulOracle, batchSize);
this.minimalSize = minimalSize;
this.rndLength = rndLength;
this.bound = bound;
this.rand = random;
}
@Override
protected Stream> generateTestWords(A hypothesis, Collection inputs) {
UniversalDeterministicAutomaton aut = hypothesis;
return doGenerateTestWords(aut, inputs);
}
/*
* Delegate target, used to bind the state-parameter of the automaton
*/
private Stream> doGenerateTestWords(UniversalDeterministicAutomaton hypothesis,
Collection inputs) {
// Note that we want to use ArrayLists because we want constant time random access
// We will sample from this for a prefix
ArrayList> stateCover = new ArrayList<>(hypothesis.size());
Covers.stateCover(hypothesis, inputs, stateCover);
// Then repeatedly from this for a random word
ArrayList arrayAlphabet = new ArrayList<>(inputs);
// Finally we test the state with a suffix
ArrayList> globalSuffixes = new ArrayList<>();
Automata.characterizingSet(hypothesis, inputs, globalSuffixes);
final Stream> result =
Stream.generate(() -> generateSingleTestWord(stateCover, arrayAlphabet, globalSuffixes));
return bound > 0 ? result.limit(bound) : result;
}
private Word generateSingleTestWord(ArrayList> stateCover,
ArrayList arrayAlphabet,
ArrayList> globalSuffixes) {
final WordBuilder wb = new WordBuilder<>(minimalSize + rndLength + 1);
// pick a random state
wb.append(stateCover.get(rand.nextInt(stateCover.size())));
// construct random middle part (of some expected length)
int size = minimalSize;
while ((size > 0) || (rand.nextDouble() > 1 / (rndLength + 1.0))) {
wb.append(arrayAlphabet.get(rand.nextInt(arrayAlphabet.size())));
if (size > 0) {
size--;
}
}
// pick a random suffix for this state
if (!globalSuffixes.isEmpty()) {
wb.append(globalSuffixes.get(rand.nextInt(globalSuffixes.size())));
}
return wb.toWord();
}
public static class DFARandomWMethodEQOracle
extends RandomWMethodEQOracle, I, Boolean>
implements DFAEquivalenceOracle {
public DFARandomWMethodEQOracle(MembershipOracle mqOracle,
int minimalSize,
int rndLength) {
super(mqOracle, minimalSize, rndLength);
}
public DFARandomWMethodEQOracle(MembershipOracle mqOracle,
int minimalSize,
int rndLength,
int bound) {
super(mqOracle, minimalSize, rndLength, bound);
}
public DFARandomWMethodEQOracle(MembershipOracle mqOracle,
int minimalSize,
int rndLength,
int bound,
int batchSize) {
super(mqOracle, minimalSize, rndLength, bound, batchSize);
}
public DFARandomWMethodEQOracle(MembershipOracle mqOracle,
int minimalSize,
int rndLength,
int bound,
Random random,
int batchSize) {
super(mqOracle, minimalSize, rndLength, bound, random, batchSize);
}
}
public static class MealyRandomWMethodEQOracle
extends RandomWMethodEQOracle, I, Word>
implements MealyEquivalenceOracle {
public MealyRandomWMethodEQOracle(MembershipOracle> mqOracle,
int minimalSize,
int rndLength) {
super(mqOracle, minimalSize, rndLength);
}
public MealyRandomWMethodEQOracle(MembershipOracle> mqOracle,
int minimalSize,
int rndLength,
int bound) {
super(mqOracle, minimalSize, rndLength, bound);
}
public MealyRandomWMethodEQOracle(MembershipOracle> mqOracle,
int minimalSize,
int rndLength,
int bound,
int batchSize) {
super(mqOracle, minimalSize, rndLength, bound, batchSize);
}
public MealyRandomWMethodEQOracle(MembershipOracle> mqOracle,
int minimalSize,
int rndLength,
int bound,
Random random,
int batchSize) {
super(mqOracle, minimalSize, rndLength, bound, random, batchSize);
}
}
}