owl:functionalProperty & owl:differentFrom

Question

I'd be grateful for some help on what I'd assumed was a very simple scenario; but being a relative newcomer to OWL and GraphDB I may have made some basic error.

I have a very simple Turtle-specified OWL example as follows:

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix demo: <urn:demo> .

demo:Gender a owl:Class .

demo:Male a demo:Gender .
demo:Female a demo:Gender .

demo:Male owl:differentFrom demo:Female .

demo:Person a owl:Class .

demo:hasGender a owl:ObjectProperty, owl:FunctionalProperty;
                rdfs:domain demo:Person;
                rdfs:range demo:Gender .

demo:Per1 a demo:Person;
            demo:hasGender demo:Male;
            demo:hasGender demo:Female .

In essence, I have a class called Gender and assert that there are 2 distinct members Male and Female.

Then I define another class Person with a functional property hasGender whose range is Gender.

Finally I assert an instance of Person, and also two separate assertions that it is both Male and Female.

Now as I understand it this is something of a contradiction; I've asserted that the hasGender property is functional so that, for a given Person, there should be only one gender. I've also asserted that Male and Female are different, so when I import this into GraphDB I was expecting it to fail because of this.

But GraphDB is happy to load both assertions. Have I missed something?

This is related to another recent question about inconsistency and GraphDB: https://stackoverflow.com/q/48155441/1260887 — Antoine Zimmermann, Feb 23 '18 at 19:45
You have missed that triple stores usually do not support full OWL reasoning, but only (mostly) some rule-based techniques which work on a fragment of OWL. — UninformedUser, Feb 24 '18 at 05:20

Stanislav Kralin · Accepted Answer · 2018-02-28T08:40:10.690

2

When creating a repository:

select the Check for inconsistencies checkbox;
select the ruleset called OWL2-RL.

If you try to import your data, GraphDB will have to say:

Could not import data; com.ontotext.trree.consistency.ConsistencyException:
Consistency check eq_diff1_1 failed:
urn:demoMale owl:differentFrom urn:demoMale
urn:demoMale owl:sameAs urn:demoMale

Alternatively, unselect the checkbox, import your data and then execute:

PREFIX sys: <http://www.ontotext.com/owlim/system#>
INSERT DATA { []  sys:consistencyCheckAgainstRuleset "owl2-rl" }

Another modelling approach is to create Male and Female as disjoint subclasses of Person.
Unlike owl:FunctionalProperty, owl:AllDisjointClasses is covered by OWL 2 QL.

edited Feb 28 '18 at 08:40

answered Feb 25 '18 at 21:42

Stanislav Kralin

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Thanks Stanislav - I assume there will be a performance penalty to both switching on consistency checking and choosing OWL2-RL over the default (RDFS-Plus Optimized) GraphDB setting for a repository? Would that affect data import, or query, or both? – wabrit Feb 26 '18 at 11:05
Of course, there will be performance penalty... Probably you could also try the "OWL2RL Optimized" ruleset. This penalty would affect data import mostly, because GraphDB *materializes* inferred statements. – Stanislav Kralin Feb 26 '18 at 11:26
@wabrit, what's preventing you from accepting the answer? – Stanislav Kralin Mar 01 '18 at 15:02

owl:functionalProperty & owl:differentFrom

1 Answers1