[sdw] [OWL-Time] OWL 2 DL violation: non-simple property in disjoint axiom (#1462)

manuel-j-diaz has just created a new issue for https://github.com/w3c/sdw:

== [OWL-Time] OWL 2 DL violation: non-simple property in disjoint axiom ==
## Problem

Even after locally implementing the proposed solution in #1461, there's another hidden OWL 2 DL violation that causes HermiT and other OWL 2 DL reasoners to reject it: `Non-simple property '<http://www.w3.org/2006/time#disjoint>' or its inverse appears in disjoint properties axiom.`

Hopefully, this report is timely for planning the next revision, @dr-shorthair .

## Root Cause
Here's what I found: 

The `time:disjoint` property:
1. Has sub-properties (`time:intervalDisjoint`, which itself has sub-properties like `time:intervalAfter` and `time:intervalBefore`)
2. Is declared with `owl:propertyDisjointWith time:notDisjoint`

Because it has sub-property chains, it means it is not simple. And it is used inside a property disjointness axiom.  That violates [OWL 2 DL §11.2](https://www.w3.org/TR/owl2-syntax/#The_Restrictions_on_the_Axiom_Closure).

## Location

[time..ttl#L592-602](https://github.com/w3c/sdw/blob/gh-pages/time/rdf/time.ttl#L592-L602):
```turtle
:disjoint
  a owl:ObjectProperty ;
  rdfs:domain :TemporalEntity ;
  rdfs:range :TemporalEntity ;
  owl:propertyDisjointWith :notDisjoint ;  # ← Violation: :disjoint is non-simple https://github.com/w3c/sdw/blob/gh-pages/time/rdf/time.ttl#L597
  rdfs:label "disjoint time entity" ;
  skos:definition "..." .
```

and [time.ttl#L650-685](https://github.com/w3c/sdw/blob/gh-pages/time/rdf/time.ttl#L677-L685):
```turtle
:intervalAfter
  rdfs:subPropertyOf :intervalDisjoint ;  # ← Transitively non-simple https://github.com/w3c/sdw/blob/gh-pages/time/rdf/time.ttl#L652
  ...

:intervalDisjoint
  a owl:ObjectProperty ;
  rdfs:subPropertyOf :disjoint ;  # ← Makes :disjoint non-simple https://github.com/w3c/sdw/blob/gh-pages/time/rdf/time.ttl#L679
  ...
```

## How to Reproduce

Locally implement fix proposed in #1461 and then run HermiT again:

```bash
docker run --rm -v $(pwd):/workspace obolibrary/robot:v1.9.8 robot \
    reason --reasoner HermiT \
        --input /workspace/owl-time.ttl
```

exit code of 1 with `Non-simple property '<http://www.w3.org/2006/time#disjoint>' or its inverse appears in disjoint properties axiom.` message.

Also tested with robot's JFact reasoner. Similar error: `Non simple role used as simple: http://www.w3.org/2006/time#before`

Please view or discuss this issue at https://github.com/w3c/sdw/issues/1462 using your GitHub account


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Received on Monday, 13 April 2026 17:25:52 UTC