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package uk.ac.ox.cs.pagoda.hermit;
import java.util.Collection;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.Set;
import org.semanticweb.HermiT.model.AnnotatedEquality;
import org.semanticweb.HermiT.model.Atom;
import org.semanticweb.HermiT.model.AtomicConcept;
import org.semanticweb.HermiT.model.AtomicRole;
import org.semanticweb.HermiT.model.Constant;
import org.semanticweb.HermiT.model.DLClause;
import org.semanticweb.HermiT.model.DLPredicate;
import org.semanticweb.HermiT.model.DatatypeRestriction;
import org.semanticweb.HermiT.model.Equality;
import org.semanticweb.HermiT.model.Individual;
import org.semanticweb.HermiT.model.NodeIDLessEqualThan;
import org.semanticweb.HermiT.model.NodeIDsAscendingOrEqual;
import org.semanticweb.HermiT.model.Term;
import org.semanticweb.HermiT.model.Variable;
import uk.ac.ox.cs.pagoda.util.Namespace;
import uk.ac.ox.cs.pagoda.util.Utility;
public class TermGraph {
Map<Term, Collection<Edge>> graph = new HashMap<Term, Collection<Edge>>();
Map<Term, Collection<AtomicConcept>> term2concepts = new HashMap<Term, Collection<AtomicConcept>>();
Set<Term> choosen = new HashSet<Term>(), allTerms = new HashSet<Term>();
DLClause clause;
Set<Atom> newBodyAtoms = new HashSet<Atom>();
public TermGraph(DLClause clause) {
this.clause = clause;
for (Atom atom: clause.getHeadAtoms())
for (int i = 0; i < atom.getArity(); ++i)
allTerms.add(atom.getArgument(i));
for (Atom atom: clause.getBodyAtoms())
for (int i = 0; i < atom.getArity(); ++i)
allTerms.add(atom.getArgument(i));
}
public DLClause simplify() {
constructGraph();
chooseTerms();
PriorityQueue<Term> queue = new PriorityQueue<Term>(allTerms.size(), new Comparator<Term>() {
@Override
public int compare(Term o1, Term o2) {
int diff = 0;
@SuppressWarnings("rawtypes")
Collection set1 = term2concepts.get(o1), set2 = term2concepts.get(o2);
int num1 = size(set1), num2 = size(set2);
if ((diff = num2 - num1) != 0)
return diff;
set1 = graph.get(o1); set2 = graph.get(o2);
num1 = size(set1); num2 = size(set2);
return num2 - num1;
}
private int size(@SuppressWarnings("rawtypes") Collection c) {
return c == null ? 0 : c.size();
}
});
for (Term term: allTerms)
queue.add(term);
while (!queue.isEmpty()) {
Term term = queue.remove();
if (!choosen.contains(term) && isRepresentative(term))
choosen.add(term);
}
boolean flag;
for (Iterator<Atom> iter = newBodyAtoms.iterator(); iter.hasNext(); ) {
flag = true;
Atom atom = iter.next();
for (int i = 0; i < atom.getArity(); ++i) {
if (!choosen.contains(atom.getArgument(i))) {
flag = false;
break;
}
}
if (!flag) iter.remove();
}
return DLClause.create(clause.getHeadAtoms(), newBodyAtoms.toArray(new Atom[0]));
}
private boolean isRepresentative(Term term) {
boolean flag = true;
for (Term otherTerm: choosen)
if (!term.equals(otherTerm) && isSubsumedBy(term, otherTerm)) {
flag = false;
}
return flag;
}
private boolean isSubsumedBy(Term t1, Term t2) {
Collection<AtomicConcept> set1 = term2concepts.get(t1);
Collection<AtomicConcept> set2 = term2concepts.get(t2);
if (set1 != null)
if (set2 == null)
return false;
else if (!set2.containsAll(set1))
return false;
Collection<Edge> edgeSet1 = graph.get(t1);
Collection<Edge> edgeSet2 = graph.get(t2);
if (edgeSet1 != null)
if (edgeSet2 == null)
return false;
else {
if (!edgeSet2.containsAll(edgeSet1))
return false;
// else {
// Collection<Edge> restEdge1 = new HashSet<Edge>();
// for (Edge edge: edgeSet1)
// if (edge.term == t2);
// else restEdge1.add(edge);
//
// Collection<Edge> restEdge2 = new HashSet<Edge>();
// for (Edge edge: edgeSet2)
// if (edge.term == t1);
// else restEdge2.add(edge);
//
// return restEdge2.containsAll(edgeSet1);
// }
}
return true;
}
private void chooseTerms() {
Set<Variable> headVariables = new HashSet<Variable>();
for (Atom atom: clause.getHeadAtoms()) {
atom.getVariables(headVariables);
}
choosen.addAll(headVariables);
for (Term term: allTerms)
if (term instanceof Constant || term instanceof Individual)
choosen.add(term);
if (choosen.isEmpty()) choosen.add(Variable.create("X"));
// propagate();
}
// private void propagate() {
// LinkedList<Term> queue = new LinkedList<Term>(choosen);
// Term term;
// while (!queue.isEmpty()) {
// term = queue.pop();
// if (graph.containsKey(term))
// for (Edge edge: graph.get(term))
// if (!choosen.contains(edge.term)) {
// choosen.add(edge.term);
// queue.add(term);
// }
// }
// }
private void constructGraph() {
DLPredicate p;
for (Atom bodyAtom: clause.getBodyAtoms()) {
p = bodyAtom.getDLPredicate();
if (p instanceof AtomicConcept) {
newBodyAtoms.add(bodyAtom);
addConcept(bodyAtom.getArgument(0), (AtomicConcept) p);
}
else if (p instanceof AtomicRole) {
newBodyAtoms.add(bodyAtom);
addEdges(bodyAtom.getArgument(0), bodyAtom.getArgument(1), (AtomicRole) p);
}
else if (p instanceof DatatypeRestriction)
newBodyAtoms.add(bodyAtom);
else if (p instanceof NodeIDLessEqualThan || p instanceof NodeIDsAscendingOrEqual);
else if (p instanceof Equality || p instanceof AnnotatedEquality) {
newBodyAtoms.add(bodyAtom);
addEdges(bodyAtom.getArgument(0), bodyAtom.getArgument(1), AtomicRole.create(Namespace.EQUALITY));
} else {
Utility.logError("Unknown DLPredicate in TermGraph: " + p);
}
}
}
private void addEdges(Term t1, Term t2, AtomicRole p) {
addEdge(t1, new Edge(p, t2, false));
addEdge(t2, new Edge(p, t1, true));
}
private void addEdge(Term t, Edge edge) {
Collection<Edge> edges;
if ((edges = graph.get(t)) == null) {
graph.put(t, edges = new HashSet<Edge>());
}
edges.add(edge);
}
private void addConcept(Term t, AtomicConcept p) {
Collection<AtomicConcept> concepts;
if ((concepts = term2concepts.get(t)) == null) {
term2concepts.put(t, concepts = new HashSet<AtomicConcept>());
}
concepts.add(p);
}
public boolean mark(Term t) {
return choosen.add(t);
}
}
class Edge {
boolean isInverse;
AtomicRole role;
Term term;
public Edge(AtomicRole role, Term term, boolean isInverse) {
this.role = role;
this.term = term;
this.isInverse = isInverse;
}
@Override
public int hashCode() {
return role.hashCode() * 1997 + term.hashCode() * 2 + (isInverse ? 1 : 0);
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof Edge)) return false;
Edge other = (Edge) obj;
return isInverse == other.isInverse && role.equals(other.role) && term.equals(other.term);
}
@Override
public String toString() {
if (isInverse)
return "inv_" + role.toString() + "_" + term.toString();
return role.toString() + "_" + term.toString();
}
}
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