Question

在Jena，我使用InfModel类创建了一个RDFS推理模型：

InfModel infmodel = ModelFactory.createRDFSModel(schema, data);

鉴于来自infmodel的推断语句，我们如何获得用于推断它的两个语句，类似于Protégé中的“解释推理”选项？例如，如果infModel包含语句:a rdf:type :t，我们可能会得到两个用于推断它的语句，例如:a :p :b和:p rdfs:domain :t。

Answer 1

根据the documentation（并使用Jena 2.11.1进行测试），您可以访问Derivation对象，这样您就可以创建对所发生事件的文本描述。在下面的示例中，我们检索了有关内部状态的更多RuleDerivation个对象。

以下是文档示例的测试实现，该示例以以下模型开头：

<urn:eg:C>  <urn:eg:p>  <urn:eg:D> .
<urn:eg:B>  <urn:eg:p>  <urn:eg:C> .
<urn:eg:A>  <urn:eg:p>  <urn:eg:B> .

......以及以下规则：

[rule1: (?a urn:eg:p ?b) (?b urn:eg:p ?c) -> (?a urn:eg:p ?c)]

...生成这个结果模型：

<urn:eg:B>  <urn:eg:p>  <urn:eg:D> , <urn:eg:C> .
<urn:eg:A>  <urn:eg:p>  <urn:eg:D> , <urn:eg:C> , <urn:eg:B> .
<urn:eg:C>  <urn:eg:p>  <urn:eg:D> .

这个基本的传递推理成为了后面这个例子的核心方面。请注意，我们获得了RuleDerivation的实例，这是您最终目标的开始。

final Resource A = ResourceFactory.createResource("urn:eg:A");
final Resource B = ResourceFactory.createResource("urn:eg:B");
final Resource C = ResourceFactory.createResource("urn:eg:C");
final Resource D = ResourceFactory.createResource("urn:eg:D");
final Property p = ResourceFactory.createProperty("urn:eg:p");

final Model rawData = ModelFactory.createDefaultModel();
rawData.add(A, p, B);
rawData.add(B, p, C);
rawData.add(C, p, D);

final String rules = "[rule1: (?a urn:eg:p ?b) (?b urn:eg:p ?c) -> (?a urn:eg:p ?c)]";
final Reasoner reasoner = new GenericRuleReasoner(Rule.parseRules(rules));
reasoner.setDerivationLogging(true);
final InfModel inf = ModelFactory.createInfModel(reasoner, rawData);

final PrintWriter out = new PrintWriter(System.out);
for (StmtIterator i = inf.listStatements(A, p, D); i.hasNext(); )
{
    Statement s = i.nextStatement();
    System.out.println("Statement is " + s);
    for (final Iterator<Derivation> id = inf.getDerivation(s); id.hasNext(); ) {
        final RuleDerivation deriv = (RuleDerivation) id.next();
        deriv.printTrace(out, true);
    }
}
out.flush();

此示例的输出为：

Statement is [urn:eg:A, urn:eg:p, urn:eg:D]
Rule rule1 concluded (urn:eg:A urn:eg:p urn:eg:D) <-
    Rule rule1 concluded (urn:eg:A urn:eg:p urn:eg:C) <-
        Fact (urn:eg:A urn:eg:p urn:eg:B)
        Fact (urn:eg:B urn:eg:p urn:eg:C)
    Fact (urn:eg:C urn:eg:p urn:eg:D)

编辑 - 提示

如果您正在寻找有关如何探索派生的示例，请查看RuleDerivation#printTrace(...)的内部。如果您想将三元组（从RuleDerivation#getMatches()）转换回语句，请使用StatementImpl#toStaetment(Triple,ModelCom)。

EDIT2 - 完成假设您使用的是Jena内置的基于规则的reasoners之一，以下代码将允许您探索由推理器报告的一个特定派生的匹配项。

final StmtIterator input = inf.listStatements(A, p, D);
assert( input.hasNext() );

final Iterator<Derivation> derivations = inf.getDerivation(input.next());
assert( null != derivations );
assert( derivations.hasNext() );

final RuleDerivation oneDerivation = (RuleDerivation) derivations.next();
final ExtendedIterator< Statement > matches = 
        new NiceIterator< Triple >()
        .andThen( oneDerivation.getMatches().iterator())
        .mapWith( new Map1< Triple, Statement >(){
            @Override
            public Statement map1( final Triple t )
            {
                /* Note that it seems that this model doesn't really mean anything. While
                 * the statement will be associated with the infModel, the triple that led
                 * to the match could have been from either the deductions graph or the
                 * raw graph. This does not actually add any triples to the underlying
                 * store.
                 */
                return StatementImpl.toStatement(t, (ModelCom)inf);
            }});

解释耶拿的推论

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