net.automatalib.util.automata.equivalence.NearLinearEquivalenceTest Maven / Gradle / Ivy
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This artifact provides various common utility operations for analyzing and manipulating
automata and graphs, such as traversal, minimization and copying.
/* Copyright (C) 2013 TU Dortmund
* This file is part of AutomataLib, http://www.automatalib.net/.
*
* AutomataLib is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 3.0 as published by the Free Software Foundation.
*
* AutomataLib 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with AutomataLib; if not, see
* http://www.gnu.de/documents/lgpl.en.html.
*/
package net.automatalib.util.automata.equivalence;
import java.util.ArrayDeque;
import java.util.Collection;
import java.util.Objects;
import java.util.Queue;
import net.automatalib.automata.UniversalDeterministicAutomaton;
import net.automatalib.automata.concepts.StateIDs;
import net.automatalib.commons.util.UnionFind;
import net.automatalib.words.Word;
import net.automatalib.words.WordBuilder;
public class NearLinearEquivalenceTest {
private static final class Record {
private final S state1;
private final S2 state2;
private final I reachedBy;
private final Record reachedFrom;
private final int depth;
public Record(S state1, S2 state2) {
this(state1, state2, null, null);
}
public Record(S state1, S2 state2, I reachedBy, Record reachedFrom) {
this.state1 = state1;
this.state2 = state2;
this.reachedBy = reachedBy;
this.reachedFrom = reachedFrom;
this.depth = (reachedFrom != null) ? reachedFrom.depth + 1 : 0;
}
}
private final UniversalDeterministicAutomaton target;
public NearLinearEquivalenceTest(UniversalDeterministicAutomaton target) {
this.target = target;
}
public Word findSeparatingWord(UniversalDeterministicAutomaton other, Collection inputs) {
return findSeparatingWord(target, other, inputs);
}
public static Word findSeparatingWord(UniversalDeterministicAutomaton target,
UniversalDeterministicAutomaton other, Collection inputs) {
int targetStates = target.size();
UnionFind uf = new UnionFind(targetStates + other.size());
S init1 = target.getInitialState();
S2 init2 = other.getInitialState();
Object sprop1 = target.getStateProperty(init1);
Object sprop2 = other.getStateProperty(init2);
if(!Objects.equals(sprop1, sprop2))
return Word.epsilon();
StateIDs targetStateIds = target.stateIDs();
StateIDs otherStateIds = other.stateIDs();
int id1 = targetStateIds.getStateId(init1);
int id2 = otherStateIds.getStateId(init2) + targetStates;
uf.link(id1, id2);
Queue> queue = new ArrayDeque>();
queue.add(new Record(init1, init2));
I lastSym = null;
Record current;
explore:while((current = queue.poll()) != null) {
S state1 = current.state1;
S2 state2 = current.state2;
for(I sym : inputs) {
T trans1 = target.getTransition(state1, sym);
T2 trans2 = other.getTransition(state2, sym);
if(trans1 == null) {
if(trans2 == null)
continue;
lastSym = sym;
break explore;
}
else if(trans2 == null) {
lastSym = sym;
break explore;
}
Object tprop1 = target.getTransitionProperty(trans1);
Object tprop2 = other.getTransitionProperty(trans2);
if(!Objects.equals(tprop1, tprop2)) {
lastSym = sym;
break explore;
}
S succ1 = target.getSuccessor(trans1);
S2 succ2 = other.getSuccessor(trans2);
id1 = targetStateIds.getStateId(succ1);
id2 = otherStateIds.getStateId(succ2) + targetStates;
int r1 = uf.find(id1), r2 = uf.find(id2);
if(r1 == r2)
continue;
sprop1 = target.getStateProperty(succ1);
sprop2 = other.getStateProperty(succ2);
if(!Objects.equals(sprop1, sprop2)) {
lastSym = sym;
break explore;
}
uf.link(r1, r2);
queue.add(new Record<>(succ1, succ2, sym, current));
}
}
if(current == null)
return null;
int ceLength = current.depth;
if(lastSym != null)
ceLength++;
WordBuilder wb = new WordBuilder(null, ceLength);
int index = ceLength;
if(lastSym != null)
wb.setSymbol(--index, lastSym);
while(current.reachedFrom != null) {
wb.setSymbol(--index, current.reachedBy);
current = current.reachedFrom;
}
return wb.toWord();
}
public static Word findSeparatingWord(UniversalDeterministicAutomaton target,
S init1, S init2, Collection inputs) {
UnionFind uf = new UnionFind(target.size());
Object sprop1 = target.getStateProperty(init1);
Object sprop2 = target.getStateProperty(init2);
if(!Objects.equals(sprop1, sprop2))
return Word.epsilon();
StateIDs stateIds = target.stateIDs();
int id1 = stateIds.getStateId(init1), id2 = stateIds.getStateId(init2);
uf.link(id1, id2);
Queue> queue = new ArrayDeque>();
queue.add(new Record(init1, init2));
I lastSym = null;
Record current;
explore:while((current = queue.poll()) != null) {
S state1 = current.state1;
S state2 = current.state2;
for(I sym : inputs) {
T trans1 = target.getTransition(state1, sym);
T trans2 = target.getTransition(state2, sym);
if(trans1 == null) {
if(trans2 == null)
continue;
lastSym = sym;
break explore;
}
else if(trans2 == null) {
lastSym = sym;
break explore;
}
Object tprop1 = target.getTransitionProperty(trans1);
Object tprop2 = target.getTransitionProperty(trans2);
if(!Objects.equals(tprop1, tprop2)) {
lastSym = sym;
break explore;
}
S succ1 = target.getSuccessor(trans1);
S succ2 = target.getSuccessor(trans2);
id1 = stateIds.getStateId(succ1);
id2 = stateIds.getStateId(succ2);
int r1 = uf.find(id1), r2 = uf.find(id2);
if(r1 == r2)
continue;
sprop1 = target.getStateProperty(succ1);
sprop2 = target.getStateProperty(succ2);
if(!Objects.equals(sprop1, sprop2)) {
lastSym = sym;
break explore;
}
uf.link(r1, r2);
queue.add(new Record<>(succ1, succ2, sym, current));
}
}
if(current == null)
return null;
int ceLength = current.depth;
if(lastSym != null)
ceLength++;
WordBuilder wb = new WordBuilder(null, ceLength);
int index = ceLength;
if(lastSym != null)
wb.setSymbol(--index, lastSym);
while(current.reachedFrom != null) {
wb.setSymbol(--index, current.reachedBy);
current = current.reachedFrom;
}
return wb.toWord();
}
}