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Posted to dev@jena.apache.org by "Andy Seaborne (JIRA)" <ji...@apache.org> on 2014/10/24 19:47:34 UTC
[jira] [Commented] (JENA-805) Graph#isIsomorphicWith should use
semantic equivalence when comparing blank nodes
[ https://issues.apache.org/jira/browse/JENA-805?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14183109#comment-14183109 ]
Andy Seaborne commented on JENA-805:
------------------------------------
By "blank node", do you mean string literals?
> Graph#isIsomorphicWith should use semantic equivalence when comparing blank nodes
> ---------------------------------------------------------------------------------
>
> Key: JENA-805
> URL: https://issues.apache.org/jira/browse/JENA-805
> Project: Apache Jena
> Issue Type: Bug
> Components: Jena
> Affects Versions: Jena 2.12.1
> Reporter: Chris Beer
> Priority: Minor
>
> It appears that Graph#isIsomorphicWith appears to use syntactic equivalence when comparing blank nodes:
> https://github.com/apache/jena/blob/master/jena-core/src/main/java/com/hp/hpl/jena/graph/impl/GraphMatcher.java#L27
> It should probably use semantic equivalence instead, or, at the very least, respect the RDF 1.1 equivalence of plain literals and xsd:string-typed literals.
> Here is an example that I believe should be considered isomorphic:
> {code}
> @Test
> public void isomorphismShouldRespectPlainLiteralEquivalence() {
> // Without worrying about a blank node, isomorphism works fine:
> Model model1 = ModelFactory.createDefaultModel();
> model1.read(IOUtils.toInputStream("<info:x> <info:y> \"x\""), "", "TTL");
> Model model2 = ModelFactory.createDefaultModel();
> model2.read(IOUtils.toInputStream("<info:x> <info:y> \"x\"^^<http://www.w3.org/2001/XMLSchema#string>"), "", "TTL");
> assertTrue(model1.isIsomorphicWith(model2)); // WORKS
> // Now with a blank node:
> Model model3 = ModelFactory.createDefaultModel();
> model3.read(IOUtils.toInputStream("<info:x> <info:y> [ <info:z> \"x\" ]"), "", "TTL");
> Model model4 = ModelFactory.createDefaultModel();
> model4.read(IOUtils.toInputStream("<info:x> <info:y> [ <info:z> \"x\"^^<http://www.w3.org/2001/XMLSchema#string> ]"), "", "TTL");
> assertTrue(model3.isIsomorphicWith(model4)); // BROKEN
> }
> {code}
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