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/*
* #%L
* ELK Reasoner
* $Id:$
* $HeadURL:$
* %%
* Copyright (C) 2011 - 2016 Department of Computer Science, University of Oxford
* %%
* 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.
* #L%
*/
package org.semanticweb.elk.reasoner.consistency;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.ConcurrentLinkedQueue;
import org.semanticweb.elk.reasoner.entailments.impl.IndividualInconsistencyEntailsOntologyInconsistencyImpl;
import org.semanticweb.elk.reasoner.entailments.impl.OntologyInconsistencyImpl;
import org.semanticweb.elk.reasoner.entailments.impl.OwlThingInconsistencyEntailsOntologyInconsistencyImpl;
import org.semanticweb.elk.reasoner.entailments.impl.TopObjectPropertyInBottomEntailsOntologyInconsistencyImpl;
import org.semanticweb.elk.reasoner.entailments.model.EntailmentInference;
import org.semanticweb.elk.reasoner.entailments.model.OntologyInconsistencyEntailmentInference;
import org.semanticweb.elk.reasoner.indexing.classes.OntologyIndexDummyChangeListener;
import org.semanticweb.elk.reasoner.indexing.model.IndexedClass;
import org.semanticweb.elk.reasoner.indexing.model.IndexedClassEntity;
import org.semanticweb.elk.reasoner.indexing.model.IndexedContextRoot;
import org.semanticweb.elk.reasoner.indexing.model.IndexedIndividual;
import org.semanticweb.elk.reasoner.indexing.model.IndexedObjectProperty;
import org.semanticweb.elk.reasoner.indexing.model.IndexedPropertyChain;
import org.semanticweb.elk.reasoner.indexing.model.OntologyIndex;
import org.semanticweb.elk.reasoner.proof.ReasonerProof;
import org.semanticweb.elk.reasoner.saturation.SaturationState;
import org.semanticweb.elk.reasoner.saturation.SaturationStateDummyChangeListener;
import org.semanticweb.elk.reasoner.saturation.conclusions.classes.SaturationConclusionBaseFactory;
import org.semanticweb.elk.reasoner.saturation.conclusions.model.ClassInconsistency;
import org.semanticweb.elk.reasoner.saturation.conclusions.model.SaturationConclusion;
import org.semanticweb.elk.reasoner.saturation.context.Context;
import org.semanticweb.elk.reasoner.stages.PropertyHierarchyCompositionState;
import org.semanticweb.elk.util.collections.Operations;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Stores information about the state of consistency checking computation
*
* @author Yevgeny Kazakov
* @author Peter Skocovsky
*/
public class ConsistencyCheckingState {
// logger for this class
private static final Logger LOGGER_ = LoggerFactory
.getLogger(ConsistencyCheckingState.class);
/**
* the saturation state of the reasoner
*/
private final SaturationState saturationState_;
private final SaturationConclusion.Factory conclusionFactory_ = new SaturationConclusionBaseFactory();
private final IndexedClass owlThing_;
private final IndexedObjectProperty bottomProperty_;
private final IndexedObjectProperty topProperty_;
/**
* {@code true} if inconsistency is derived for {@code owl:Thing}
*/
private volatile boolean isOwlThingInconsistent_ = false;
/**
* {@code true} if inconsistency is derived for
* {@code owl:bottomObjectProperty}
*/
private volatile boolean isTopObjectPropertyInBottom_ = false;
/**
* the set of individuals for which inconsistency is derived
*/
private final Set inconsistentIndividuals_ = Collections
.synchronizedSet(new HashSet());
/**
* the entities for which consistency needs to be checked
*/
private final Queue toDoEntities_;
private ConsistencyCheckingState(
SaturationState saturationState,
final PropertyHierarchyCompositionState propertHierarchyState) {
this.saturationState_ = saturationState;
final OntologyIndex index = saturationState.getOntologyIndex();
this.owlThing_ = index.getOwlThing();
this.bottomProperty_ = index.getOwlBottomObjectProperty();
this.topProperty_ = index.getOwlTopObjectProperty();
toDoEntities_ = new ConcurrentLinkedQueue(
index.getIndividuals());
toDoEntities_.add(index.getOwlThing());
// listening to changes in the ontology
index.addListener(new OntologyIndexDummyChangeListener() {
@Override
public void individualAddition(IndexedIndividual ind) {
toDoEntities_.add(ind);
}
@Override
public void individualRemoval(IndexedIndividual ind) {
inconsistentIndividuals_.remove(ind);
}
});
// listening to changes in the saturation state
saturationState
.addListener(new SaturationStateDummyChangeListener() {
@Override
public void contextsClear() {
toDoEntities_.addAll(index.getIndividuals());
toDoEntities_.add(owlThing_);
inconsistentIndividuals_.clear();
isOwlThingInconsistent_ = false;
}
@Override
public void contextMarkedNonSaturated(C context) {
IndexedContextRoot root = context.getRoot();
if (root instanceof IndexedIndividual) {
IndexedIndividual ind = (IndexedIndividual) root;
inconsistentIndividuals_.remove(ind);
toDoEntities_.add(ind);
} else if (root == owlThing_) {
isOwlThingInconsistent_ = false;
toDoEntities_.add(owlThing_);
}
}
@Override
public void contextMarkedSaturated(C context) {
IndexedContextRoot root = context.getRoot();
if (!context.containsConclusion(
conclusionFactory_.getContradiction(root))) {
return;
}
// else
if (root instanceof IndexedIndividual) {
tellInconsistentIndividual(
(IndexedIndividual) root);
} else if (root == owlThing_) {
tellInconsistentOwlThing();
}
}
});
// listening to changes in the property hierarchy state
propertHierarchyState
.addListener(new PropertyHierarchyCompositionState.Listener() {
@Override
public void propertyBecameSaturated(
final IndexedPropertyChain chain) {
if (bottomProperty_ == chain && chain.getSaturated()
.getSubProperties().contains(topProperty_)) {
tellTopObjectPropertyInBottom();
}
}
@Override
public void propertyBecameNotSaturated(
final IndexedPropertyChain chain) {
if (bottomProperty_ == chain) {
isTopObjectPropertyInBottom_ = false;
}
}
});
}
/**
* @param saturationState
* a {@link SaturationState} containing information about derived
* class axioms
* @param propertHierarchyState
* a {@link PropertyHierarchyCompositionState} containing
* information about derived property axioms
*
* @return a new {@link ConsistencyCheckingState} associated with the given
* {@link SaturationState} and {@link PropertyHierarchyCompositionState}
*/
public static ConsistencyCheckingState create(
SaturationState saturationState,
final PropertyHierarchyCompositionState propertHierarchyState) {
return new ConsistencyCheckingState(saturationState,
propertHierarchyState);
}
/**
* Removes from {@link #toDoEntities_} the entities which no longer occur in
* the ontology or for the context is already saturated (thus consistency is
* already checked)
*
* @return the number of the remaining entries in {@link #toDoEntities_}
*/
private int pruneToDo() {
int size = 0;
Iterator itr = toDoEntities_.iterator();
while (itr.hasNext()) {
IndexedClassEntity next = itr.next();
if (!next.occurs()) {
itr.remove();
continue;
}
// else
Context context = saturationState_.getContext(next);
if (context != null && context.isSaturated()) {
itr.remove();
continue;
}
size++;
}
return size;
}
public Collection getTestEntitites() {
int size = pruneToDo();
// since getting the size of the queue is not a linear operation,
// use the computed size
return Operations.getCollection(toDoEntities_, size);
}
/**
* tells that {@code owl:Thing} is inconsistent in the
* {@link SaturationState}, i.e., its context is saturated and contains
* {@link ClassInconsistency}
*/
private void tellInconsistentOwlThing() {
isOwlThingInconsistent_ = true;
LOGGER_.trace("owl:Thing inconsistent");
}
/**
* tells that derived sub-properties of {@code owl:bottomObjectProperty}
* contain {@code owl:topObjectProperty}
*/
private void tellTopObjectPropertyInBottom() {
isTopObjectPropertyInBottom_ = true;
LOGGER_.trace(
"owl:topObjectProperty is a sub-property of owl:bottomObjectProperty");
}
/**
* tells that the given {@link IndexedIndividual} is inconsistent in the
* {@link SaturationState},
*
* @param ind
*/
private void tellInconsistentIndividual(IndexedIndividual ind) {
inconsistentIndividuals_.add(ind);
LOGGER_.trace("{} inconsistent", ind);
}
/**
* @return {@code true} if the ontology is currently in the inconsistent
* state
*/
public boolean isInconsistent() {
return isOwlThingInconsistent_ || isTopObjectPropertyInBottom_
|| !inconsistentIndividuals_.isEmpty();
}
/**
* @return {@code true} if inconsistency for {@code owl:Thing} is derived
*/
public boolean isOwlThingInconsistent() {
return isOwlThingInconsistent_;
}
/**
* @return {@code true} if inconsistency is derived from object property
* hierarchy
*/
public boolean isTopObjectPropertyInBottom() {
return isTopObjectPropertyInBottom_;
}
/**
* @return all individuals for which inconsistency is derived
*/
public Collection getInconsistentIndividuals() {
return inconsistentIndividuals_;
}
/**
* Explains why an ontology inconsistency is entailed. If it is not
* entailed, the returned proof is empty.
*
* @param atMostOne
* Whether at most one explanation should be returned.
* @return An evidence of entailment of ontology inconsistency.
*/
public ReasonerProof getEvidence(
final boolean atMostOne) {
return new ReasonerProof() {
@Override
public Collection getInferences(
final Object conclusion) {
if (!OntologyInconsistencyImpl.INSTANCE.equals(conclusion)) {
return Collections.emptyList();
}
// else
final Collection inconsistentIndividuals = getInconsistentIndividuals();
Iterable result = Operations
.map(inconsistentIndividuals,
INDIVIDUAL_TO_ENTAILMENT_INFERENCE);
int size = inconsistentIndividuals.size();
if (isTopObjectPropertyInBottom_) {
result = Operations.concat(Operations
. singleton(
new TopObjectPropertyInBottomEntailsOntologyInconsistencyImpl(
conclusionFactory_
.getSubPropertyChain(
topProperty_,
bottomProperty_))),
result);
size++;
}
if (isOwlThingInconsistent_) {
result = Operations.concat(Operations
. singleton(
new OwlThingInconsistencyEntailsOntologyInconsistencyImpl(
conclusionFactory_.getContradiction(
owlThing_))),
result);
size++;
}
if (atMostOne) {
final Iterator iter = result
.iterator();
if (!iter.hasNext()) {
return Collections.emptyList();
}
// else
return Collections.singleton(iter.next());
}
// else
return Operations.getCollection(result, size);
}
};
}
private final Operations.Transformation INDIVIDUAL_TO_ENTAILMENT_INFERENCE = new Operations.Transformation() {
@Override
public OntologyInconsistencyEntailmentInference transform(
final IndexedIndividual ind) {
return new IndividualInconsistencyEntailsOntologyInconsistencyImpl(
conclusionFactory_.getContradiction(ind),
ind.getElkEntity());
}
};
}