com.bigdata.rdf.rules.InferenceEngine Maven / Gradle / Ivy
/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
[email protected]
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package com.bigdata.rdf.rules;
import java.util.Properties;
import org.apache.log4j.Logger;
import com.bigdata.bop.joinGraph.fast.DefaultEvaluationPlanFactory2;
import com.bigdata.rdf.axioms.Axioms;
import com.bigdata.rdf.axioms.NoAxioms;
import com.bigdata.rdf.axioms.RdfsAxioms;
import com.bigdata.rdf.inf.BackchainTypeResourceIterator;
import com.bigdata.rdf.inf.ClosureStats;
import com.bigdata.rdf.inf.Justification;
import com.bigdata.rdf.inf.TruthMaintenance;
import com.bigdata.rdf.store.AbstractTripleStore;
import com.bigdata.rdf.store.DataLoader;
import com.bigdata.rdf.store.TempTripleStore;
import com.bigdata.relation.accesspath.IElementFilter;
import com.bigdata.relation.rule.Program;
import com.bigdata.relation.rule.eval.ActionEnum;
import com.bigdata.relation.rule.eval.IJoinNexus;
import com.bigdata.relation.rule.eval.IJoinNexusFactory;
/**
* Flyweight object encapsulates some configuration state and provides methods
* to compute or update the closure of the database. An instance of this is
* obtained from {@link AbstractTripleStore#getInferenceEngine()}.
*
* @author Bryan Thompson
* @version $Id$
*
* @todo Improve write efficiency for the proofs - they are slowing things way
* down. Perhaps turn off the range count metadata inside of the B+Tree
* for that index? Note that using magic sets or a backward chainer will
* let us avoid writing proofs altogether since we can prove whether or
* not a statement is still entailed without recourse to reading proofs
* chains.
*
* @todo explore an option for "owl:sameAs" semantics using destructive merging
* (the terms are assigned the same term identifier, one of them is
* treated as a canonical, and there is no way to retract the sameAs
* assertion). If you take this approach then you must also re-write all
* existing assertions using the term whose term identifier is changed to
* be that of another term.
*/
public class InferenceEngine {
final static protected Logger log = Logger.getLogger(InferenceEngine.class);
/**
* True iff the {@link #log} level is INFO or less.
*/
final static protected boolean INFO = log.isInfoEnabled();
/**
* True iff the {@link #log} level is DEBUG or less.
*/
final static protected boolean DEBUG = log.isDebugEnabled();
/**
* The database whose closure is being maintained.
*/
final public AbstractTripleStore database;
/**
* A filter for keeping certain entailments out of the database. It is
* configured based on how the {@link InferenceEngine} is configured.
*
* @see DoNotAddFilter
*/
public final DoNotAddFilter doNotAddFilter;
/**
* Options for the {@link InferenceEngine}.
*
* @author Bryan Thompson
* @version $Id$
*/
public static interface Options {
/**
* When true (default
* {@value #DEFAULT_FORWARD_RDF_TYPE_RDFS_RESOURCE})
* (?x rdf:type rdfs:Resource) entailments are computed
* AND stored in the database. When false, rules that
* produce those entailments are turned off such that they are neither
* computed NOR stored and a backward chainer or magic sets technique
* must be used to generate the entailments at query time.
*
* Note: Eagerly materializing those entailments takes a lot of time and
* space but it reduces time during query IF you are asking for these
* entailments (many realistic queries do not). Therefore it is
* generally a win to turn this option off.
*
* @see BackchainAccessPath
* @see BackchainTypeResourceIterator
*/
String FORWARD_CHAIN_RDF_TYPE_RDFS_RESOURCE = InferenceEngine.class
.getName()
+ ".forwardChainRdfTypeRdfsResource";
String DEFAULT_FORWARD_RDF_TYPE_RDFS_RESOURCE = "false";
/**
* When true (default
* {@value #DEFAULT_FORWARD_CHAIN_OWL_SAMEAS_CLOSURE}) the reflexive
* entailments for owl:sameAs are computed by forward
* chaining and stored in the database unless
* {@link com.bigdata.rdf.store.AbstractTripleStore.Options#AXIOMS_CLASS}
* is used to completely disable those entailments, e.g., by specifying
* either {@link NoAxioms} or {@link RdfsAxioms}. When
* false those entailments are not computed and
* owl:sameAs processing is disabled.
*/
String FORWARD_CHAIN_OWL_SAMEAS_CLOSURE = InferenceEngine.class
.getName()
+ ".forwardChainOwlSameAsClosure";
String DEFAULT_FORWARD_CHAIN_OWL_SAMEAS_CLOSURE = "true";
/**
* When true (default
* {@value #DEFAULT_FORWARD_CHAIN_OWL_SAMEAS_PROPERTIES}) the
* entailments that replication properties between instances that are
* identified as "the same" using owl:sameAs will be
* forward chained and stored in the database. When false,
* rules that produce those entailments are turned off such that they
* are neither computed NOR stored and the entailments may be accessed
* at query time using the {@link BackchainAccessPath}.
*
* Note: The default is false since those entailments can
* take up a LOT of space in the store and are expensive to compute
* during data load. It is a lot easier to compute them dynamically when
* presented with a specific triple pattern. While more computation is
* performed if a fill triple scan is frequently requested, that is an
* unusual case and significantly less data will be stored regardless.
*
* Note: I've changed the default to true until we fix the query
* time computation, which is currently broken. --MP
*
* @see BackchainAccessPath
*/
String FORWARD_CHAIN_OWL_SAMEAS_PROPERTIES = InferenceEngine.class
.getName()
+ ".forwardChainOwlSameAsProperties";
String DEFAULT_FORWARD_CHAIN_OWL_SAMEAS_PROPERTIES = "true";
/**
* When true (default
* {@value #DEFAULT_FORWARD_CHAIN_OWL_EQUIVALENT_PROPERTY}) the
* entailments for owl:equivilantProperty are computed by
* forward chaining and stored in the database. When false,
* rules that produce those entailments are turned off such that they
* are neither computed NOR stored and a backward chainer or magic sets
* technique must be used to generate the entailments at query time.
*
* @todo implement backward chaining for owl:equivalentProperty and
* compare performance?
*/
String FORWARD_CHAIN_OWL_EQUIVALENT_PROPERTY = InferenceEngine.class
.getName()
+ ".forwardChainOwlEquivalentProperty";
String DEFAULT_FORWARD_CHAIN_OWL_EQUIVALENT_PROPERTY = "true";
/**
* When true (default
* {@value #DEFAULT_FORWARD_CHAIN_OWL_EQUIVALENT_CLASS}) the
* entailments for owl:equivilantClass are computed by
* forward chaining and stored in the database. When false,
* rules that produce those entailments are turned off such that they
* are neither computed NOR stored and a backward chainer or magic sets
* technique must be used to generate the entailments at query time.
*
* @todo implement backward chaining for owl:equivalentClass and compare
* performance?
*/
String FORWARD_CHAIN_OWL_EQUIVALENT_CLASS = InferenceEngine.class
.getName()
+ ".forwardChainOwlEquivalentClass";
String DEFAULT_FORWARD_CHAIN_OWL_EQUIVALENT_CLASS = "true";
/**
* When true (default
* {@value #FORWARD_CHAIN_OWL_INVERSE_OF}) the entailments for
* owl:InverseOf are computed by forward chaining and
* stored in the database. When false, rules that
* produce those entailments are turned off such that they are neither
* computed NOR stored and a backward chainer or magic sets technique
* must be used to generate the entailments at query time.
*/
String FORWARD_CHAIN_OWL_INVERSE_OF = InferenceEngine.class.getName()
+ ".forwardChainOwlInverseOf";
String DEFAULT_FORWARD_CHAIN_OWL_INVERSE_OF = "true";
/**
* When true (default
* {@value #DEFAULT_FORWARD_CHAIN_OWL_TRANSITIVE_PROPERTY}) the
* entailments for owl:TransitiveProperty are computed by
* forward chaining and stored in the database. When false,
* rules that produce those entailments are turned off such that they
* are neither computed NOR stored and a backward chainer or magic sets
* technique must be used to generate the entailments at query time.
*/
String FORWARD_CHAIN_OWL_TRANSITIVE_PROPERTY = InferenceEngine.class
.getName()
+ ".forwardChainOwlTransitiveProperty";
String DEFAULT_FORWARD_CHAIN_OWL_TRANSITIVE_PROPERTY = "true";
/**
* When true (default
* {@value #DEFAULT_FORWARD_CHAIN_OWL_HAS_VALUE}) the
* entailments for owl:hasValue are computed by
* forward chaining and stored in the database. When false,
* rules that produce those entailments are turned off such that they
* are neither computed NOR stored and a backward chainer or magic sets
* technique must be used to generate the entailments at query time.
*/
String FORWARD_CHAIN_OWL_HAS_VALUE = InferenceEngine.class
.getName()
+ ".forwardChainOwlHasValue";
String DEFAULT_FORWARD_CHAIN_OWL_HAS_VALUE = "true";
/**
* When true (default
* {@value #DEFAULT_FORWARD_CHAIN_OWL_SYMMETRIC_PROPERTY}) the
* entailments for owl:SymmetricProperty are computed by
* forward chaining and stored in the database. When false,
* rules that produce those entailments are turned off such that they
* are neither computed NOR stored and a backward chainer or magic sets
* technique must be used to generate the entailments at query time.
*/
String FORWARD_CHAIN_OWL_SYMMETRIC_PROPERTY = InferenceEngine.class
.getName()
+ ".forwardChainOwlSymmetricProperty";
String DEFAULT_FORWARD_CHAIN_OWL_SYMMETRIC_PROPERTY = "true";
/**
* When true (default
* {@value #DEFAULT_ENABLE_OWL_FUNCTIONAL_AND_INVERSE_FUNCTIONAL_PROPERTY}
* ) the data is tested for violations of owl:FunctionalProperty and
* owl:InverseFunctionalProperty. When this is enabled, closure will
* fail if violations are found in the data.
*/
String ENABLE_OWL_FUNCTIONAL_AND_INVERSE_FUNCTIONAL_PROPERTY = InferenceEngine.class
.getName()
+ ".enableOwlFunctionalAndInverseFunctionalProperty";
String DEFAULT_ENABLE_OWL_FUNCTIONAL_AND_INVERSE_FUNCTIONAL_PROPERTY = "true";
}
/**
* Configure {@link InferenceEngine} using the properties used to configure
* the database.
*
* @param database
* The database.
*
* @see AbstractTripleStore#getInferenceEngine()
*/
public InferenceEngine(AbstractTripleStore database) {
if (database == null)
throw new IllegalArgumentException();
this.database = database;
final Properties properties = database.getProperties();
this.forwardChainRdfTypeRdfsResource = Boolean.parseBoolean(properties
.getProperty(Options.FORWARD_CHAIN_RDF_TYPE_RDFS_RESOURCE,
Options.DEFAULT_FORWARD_RDF_TYPE_RDFS_RESOURCE));
if(INFO)
log.info(Options.FORWARD_CHAIN_RDF_TYPE_RDFS_RESOURCE + "="
+ forwardChainRdfTypeRdfsResource);
final Axioms axioms = database.getAxioms();
final boolean rdfsOnly = axioms.isRdfSchema() && !axioms.isOwlSameAs();
if (rdfsOnly) {
this.forwardChainOwlSameAsClosure = false;
this.forwardChainOwlSameAsProperties = false;
this.forwardChainOwlEquivalentProperty = false;
this.forwardChainOwlEquivalentClass = false;
this.forwardChainOwlInverseOf = false;
this.forwardChainOwlTransitiveProperty = false;
this.forwardChainOwlHasValue = false;
this.forwardChainOwlSymmetricProperty = false;
this.enableOwlFunctionalAndInverseFunctionalProperty = false;
} else {
this.forwardChainOwlSameAsClosure = Boolean.parseBoolean(properties
.getProperty(Options.FORWARD_CHAIN_OWL_SAMEAS_CLOSURE,
Options.DEFAULT_FORWARD_CHAIN_OWL_SAMEAS_CLOSURE));
if(INFO)
log.info(Options.FORWARD_CHAIN_OWL_SAMEAS_CLOSURE + "="
+ forwardChainOwlSameAsClosure);
if(forwardChainOwlSameAsClosure) {
this.forwardChainOwlSameAsProperties = Boolean.parseBoolean(properties
.getProperty(Options.FORWARD_CHAIN_OWL_SAMEAS_PROPERTIES,
Options.DEFAULT_FORWARD_CHAIN_OWL_SAMEAS_PROPERTIES));
} else {
this.forwardChainOwlSameAsProperties = false;
}
if(INFO)
log.info(Options.FORWARD_CHAIN_OWL_SAMEAS_CLOSURE + "="
+ forwardChainOwlSameAsClosure);
this.forwardChainOwlEquivalentProperty = Boolean
.parseBoolean(properties
.getProperty(
Options.FORWARD_CHAIN_OWL_EQUIVALENT_PROPERTY,
Options.DEFAULT_FORWARD_CHAIN_OWL_EQUIVALENT_PROPERTY));
if(INFO)
log.info(Options.FORWARD_CHAIN_OWL_EQUIVALENT_PROPERTY + "="
+ forwardChainOwlEquivalentProperty);
this.forwardChainOwlEquivalentClass = Boolean
.parseBoolean(properties.getProperty(
Options.FORWARD_CHAIN_OWL_EQUIVALENT_CLASS,
Options.DEFAULT_FORWARD_CHAIN_OWL_EQUIVALENT_CLASS));
if(INFO)
log.info(Options.FORWARD_CHAIN_OWL_EQUIVALENT_CLASS + "="
+ forwardChainOwlEquivalentClass);
this.forwardChainOwlInverseOf = Boolean
.parseBoolean(properties.getProperty(
Options.FORWARD_CHAIN_OWL_INVERSE_OF,
Options.DEFAULT_FORWARD_CHAIN_OWL_INVERSE_OF));
if(INFO)
log.info(Options.FORWARD_CHAIN_OWL_INVERSE_OF + "="
+ forwardChainOwlInverseOf);
this.forwardChainOwlTransitiveProperty = Boolean
.parseBoolean(properties.getProperty(
Options.FORWARD_CHAIN_OWL_TRANSITIVE_PROPERTY,
Options.DEFAULT_FORWARD_CHAIN_OWL_TRANSITIVE_PROPERTY));
if(INFO)
log.info(Options.FORWARD_CHAIN_OWL_TRANSITIVE_PROPERTY + "="
+ forwardChainOwlTransitiveProperty);
this.forwardChainOwlHasValue = Boolean
.parseBoolean(properties.getProperty(
Options.FORWARD_CHAIN_OWL_HAS_VALUE,
Options.DEFAULT_FORWARD_CHAIN_OWL_HAS_VALUE));
if(INFO)
log.info(Options.FORWARD_CHAIN_OWL_HAS_VALUE + "="
+ forwardChainOwlHasValue);
this.forwardChainOwlSymmetricProperty = Boolean
.parseBoolean(properties.getProperty(
Options.FORWARD_CHAIN_OWL_SYMMETRIC_PROPERTY,
Options.DEFAULT_FORWARD_CHAIN_OWL_SYMMETRIC_PROPERTY));
if(INFO)
log.info(Options.FORWARD_CHAIN_OWL_SYMMETRIC_PROPERTY + "="
+ forwardChainOwlSymmetricProperty);
this.enableOwlFunctionalAndInverseFunctionalProperty = Boolean
.parseBoolean(properties.getProperty(
Options.ENABLE_OWL_FUNCTIONAL_AND_INVERSE_FUNCTIONAL_PROPERTY,
Options.DEFAULT_ENABLE_OWL_FUNCTIONAL_AND_INVERSE_FUNCTIONAL_PROPERTY));
if(INFO)
log.info(Options.ENABLE_OWL_FUNCTIONAL_AND_INVERSE_FUNCTIONAL_PROPERTY + "="
+ enableOwlFunctionalAndInverseFunctionalProperty);
}
doNotAddFilter = new DoNotAddFilter(database.getVocabulary(), database
.getAxioms(), forwardChainRdfTypeRdfsResource);
}
/**
* The object that generates the {@link Program}s that we use to maintain
* the closure of the database.
*
* Note: This is lazily instantiated in order to avoid a cyclic
* initialization dependency between the {@link InferenceEngine} and the
* {@link BaseClosure} constructors.
*/
private BaseClosure baseClosure = null;
/**
* Set based on {@link Options#FORWARD_CHAIN_RDF_TYPE_RDFS_RESOURCE}. When
* true the {@link InferenceEngine} is configured to forward
* chain and store entailments of the form
* (x rdf:type rdfs:Resource). When false,
* those entailments are computed at query time by
* {@link #backchainIterator(long, long, long)}.
*/
final protected boolean forwardChainRdfTypeRdfsResource;
/**
* Set based on {@link Options#FORWARD_CHAIN_OWL_SAMEAS_CLOSURE}. When
* true we will forward chain and store the reflexive and
* transitive closure of owl:sameAs using
* {@link RuleOwlSameAs1} and {@link RuleOwlSameAs2}.
*
* Note: When false, NO owl:sameAs processing will be
* performed since there is no privision for backward chaining the
* owl:sameAs closure.
*/
final protected boolean forwardChainOwlSameAsClosure;
/**
* Set based on {@link Options#FORWARD_CHAIN_OWL_SAMEAS_PROPERTIES}. When
* true, we will forward chain {@link RuleOwlSameAs2} and
* {@link RuleOwlSameAs3} which replicate properties on individuals
* identified as the "same" by owl:sameAs. When
* false, we will compute those entailments at query time in
* {@link #backchainIterator(long, long, long)}.
*/
final protected boolean forwardChainOwlSameAsProperties;
/**
* Set based on {@link Options#FORWARD_CHAIN_OWL_EQUIVALENT_PROPERTY}. When
* true, we will forward chain and store those entailments.
* When false, those entailments will NOT be available.
*/
final protected boolean forwardChainOwlEquivalentProperty;
/**
* Set based on {@link Options#FORWARD_CHAIN_OWL_EQUIVALENT_CLASS}. When
* true, we will forward chain and store those entailments.
* When false, those entailments will NOT be available.
*/
final protected boolean forwardChainOwlEquivalentClass;
/**
* Set based on {@link Options#FORWARD_CHAIN_OWL_INVERSE_OF}. When
* true, we will forward chain and store those entailments.
* When false, those entailments will NOT be available.
*/
final protected boolean forwardChainOwlInverseOf;
/**
* Set based on {@link Options#FORWARD_CHAIN_OWL_TRANSITIVE_PROPERTY}. When
* true, we will forward chain and store those entailments.
* When false, those entailments will NOT be available.
*/
final protected boolean forwardChainOwlTransitiveProperty;
/**
* Set based on {@link Options#FORWARD_CHAIN_OWL_HAS_VALUE}. When
* true, we will forward chain and store those entailments.
* When false, those entailments will NOT be available.
*/
final protected boolean forwardChainOwlHasValue;
/**
* Set based on {@link Options#FORWARD_CHAIN_OWL_SYMMETRIC_PROPERTY}. When
* true, we will forward chain and store those entailments.
* When false, those entailments will NOT be available.
*/
final protected boolean forwardChainOwlSymmetricProperty;
/**
* Set based on {@link Options#ENABLE_OWL_FUNCTIONAL_AND_INVERSE_FUNCTIONAL_PROPERTY}. When
* true, we will test for violations of owl:FunctionalProperty and
* owl:InverseFunctionalProperty.
*/
final protected boolean enableOwlFunctionalAndInverseFunctionalProperty;
/**
* Compute the forward closure of a focusStore against the database using
* the algorithm selected by
* {@link AbstractTripleStore.Options#CLOSURE_CLASS}.
*
* Note: before calling this method with a non-null
* focusStore, the caller SHOULD examine the statements in the
* focusStore and then database. For each statement in the
* focusStore, if this statement exists explicitly in the database then
* remove it from the focusStore. If this statement exists implicitly in the
* database. Regardless of whether the statement was explicit or inferred in
* the database, remove it from the focusStore. This step prevents the
* needless (and expensive) reapplication of the rules to data already known
* to the database!
*
* Note: If the focusStore is given, then the entailments will be
* asserted against the focusStore. Either this method or the caller MUST
* copy the focusStore onto the database using
* {@link AbstractTripleStore#copyStatements(AbstractTripleStore, IElementFilter, boolean)}.
* If you are loading data from some kind of resource, then see
* {@link DataLoader} which already knows how to do this.
*
* See {@link TruthMaintenance#assertAll(TempTripleStore)}, which first
* handles statements already in the database, then calls this method, and
* finally copies the remaining explicit statements in the focusStore and
* the entailments into the database.
*
* @param focusStore
* The data set that will be closed against the database
* (optional). When null the store will be closed
* against itself.
*
* @return Statistics about the operation.
*/
public ClosureStats computeClosure(AbstractTripleStore focusStore) {
return computeClosure(focusStore, database.isJustify());
}
/**
* This variant allows you to explicitly NOT generate {@link Justification}s
* for the computed entailments. It is used by the {@link TruthMaintenance}
* class as part of the algorithm for truth maintenance when retracting
* statements from the database. It SHOULD NOT be used for any other purpose
* or you may risk failing to generate justifications.
*
* Note: While this is synchronized, there is a stronger constraint on truth
* maintenance -- only one process can safely update the closure of the
* database at a time. Concurrent closure updates will result in an
* incoherent knowledge base (the closure will not be at fixed point but the
* underlying indices will be coherent). Closure operations MUST be
* serialized to avoid inconsistency in the knowledge base.
*
* @param focusStore
* The data set that will be closed against the database.
* @param justify
* {@link Justification}s will be generated iff this flag is
* true.
*
* @return Statistics about the operation.
*
* @see #computeClosure(AbstractTripleStore)
*/
public synchronized ClosureStats computeClosure(
AbstractTripleStore focusStore, boolean justify) {
if (baseClosure == null) {
baseClosure = database.getClosureInstance();
}
final MappedProgram program = baseClosure.getProgram(
database.getSPORelation().getNamespace(),//
(focusStore == null ? null : focusStore.getSPORelation()
.getNamespace()) //
);
if(INFO) {
log.info("\n\nforwardClosure=" + baseClosure.getClass().getName()
+ ", program=" + program);
}
try {
final long begin = System.currentTimeMillis();
/*
* FIXME remove IJoinNexus.RULE once we we can generate the
* justifications from just the bindings and no longer need the rule
* to generate the justifications (esp. for scale-out).
*/
final int solutionFlags = IJoinNexus.ELEMENT//
| (justify ? IJoinNexus.RULE | IJoinNexus.BINDINGS : 0)//
// | IJoinNexus.RULE // iff debugging.
;
final RuleContextEnum ruleContext = focusStore == null
? RuleContextEnum.DatabaseAtOnceClosure
: RuleContextEnum.TruthMaintenance
;
final IJoinNexusFactory joinNexusFactory = database
.newJoinNexusFactory(ruleContext, ActionEnum.Insert,
solutionFlags, doNotAddFilter, justify,
false/* backchain */,
DefaultEvaluationPlanFactory2.INSTANCE);
final IJoinNexus joinNexus = joinNexusFactory.newInstance(database
.getIndexManager());
final long mutationCount = joinNexus.runMutation(program);
final long elapsed = System.currentTimeMillis() - begin;
return new ClosureStats(mutationCount, elapsed);
} catch (Exception ex) {
throw new RuntimeException(ex);
}
}
}