[I] riot --rdfs: rdfs:subPropertyOf ignored unless the vocabulary has an rdfs:subClassOf, and never combined with rdfs:domain/rdfs:range [jena]

["rybesh (via GitHub)" <gi...@apache.org>]

rybesh opened a new issue, #4312:
URL: https://github.com/apache/jena/issues/4312

   ### Version
   
   6.2.0 (also 5.5.0)
   
   ### What happened?
   
   Streaming RDFS inference (`riot --rdfs=VOCAB`, i.e. `InfStreamRDFS` / `ApplyRDFS`) handles `rdfs:subPropertyOf` incorrectly in two ways.
   
   **1. `rdfs:subPropertyOf` is skipped when the vocabulary has no `rdfs:subClassOf` triple.**
   
   `vocab1.ttl`:
   ```turtle
   PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
   PREFIX : <http://example/>
   :p rdfs:subPropertyOf :q .
   :q rdfs:domain :D .
   ```
   
   `vocab2.ttl` is the same plus one unrelated subclass triple:
   ```turtle
   PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
   PREFIX : <http://example/>
   :p rdfs:subPropertyOf :q .
   :q rdfs:domain :D .
   :A rdfs:subClassOf :B .
   ```
   
   `data.ttl`:
   ```turtle
   PREFIX : <http://example/>
   :x :p :y .
   ```
   
   With `vocab1.ttl`, nothing is inferred. With `vocab2.ttl`, `:x :q :y` is inferred (rdfs7). Adding an unrelated `rdfs:subClassOf` should not change whether rdfs7 applies.
   
   This looks like a copy-paste slip in `ApplyRDFS.subProperty()`. Its short-circuit tests `hasClassDeclarations()`, the same test `subClass()` uses, where it should test `hasPropertyDeclarations()`:
   https://github.com/apache/jena/blob/d77438478938cc651760f4a61e5d9ee7acff072b/jena-arq/src/main/java/org/apache/jena/rdfs/engine/ApplyRDFS.java#L102-L103
   
   **2. A superproperty's domain and range are never applied.**
   
   Even with `vocab2.ttl`, `:x rdf:type :D` is not inferred. By rdfs7, `:x :q :y` holds, and by rdfs2, `:q rdfs:domain :D` then gives `:x rdf:type :D`. The same is true for `rdfs:range` (rdfs3).
   
   `ApplyRDFS.domain()` and `range()` look up only the asserted predicate (`setup.getDomain(p)`), so the triples that `subProperty()` derives never go through domain and range:
   https://github.com/apache/jena/blob/d77438478938cc651760f4a61e5d9ee7acff072b/jena-arq/src/main/java/org/apache/jena/rdfs/engine/ApplyRDFS.java#L63-L74
   
   The backward-chaining graph has the same gap. With `RDFSFactory.graphRDFS(data, vocab1)`, `find(ANY, ANY, ANY)` returns `:x :q :y` but not `:x rdf:type :D`, and neither do `find(:x, rdf:type, :D)` or `find(ANY, rdf:type, :D)`. `MatchRDFS` uses `getDomain`/`getRange` and `getPropertiesByDomain`/`getPropertiesByRange` without considering sub-/super-properties.
   
   Expected for `riot --rdfs=vocab1.ttl data.ttl` (and for `vocab2.ttl`):
   ```
   <http://example/x> <http://example/p> <http://example/y> .
   <http://example/x> <http://example/q> <http://example/y> .
   <http://example/x> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://example/D> .
   ```
   
   For comparison, the textbook example in Allemang, Hendler & Gandon, *Semantic Web for the Working Ontologist* (2nd ed., ch. 8), uses only `rdfs:subPropertyOf` (`:freeLancesTo rdfs:subPropertyOf :contractsTo`, `:contractsTo rdfs:subPropertyOf :worksFor`, …). With `riot --rdfs` it infers nothing at all.
   
   Related: #3507 (other RDFS engine issues) and #1720.
   
   ### Relevant output and stacktrace
   
   ```shell
   $ riot --version
   Apache Jena RIOT version 6.2.0
   $ riot --rdfs=vocab1.ttl data.ttl
   <http://example/x> <http://example/p> <http://example/y> .
   $ riot --rdfs=vocab2.ttl data.ttl
   <http://example/x> <http://example/p> <http://example/y> .
   <http://example/x> <http://example/q> <http://example/y> .
   ```
   
   ### Are you interested in making a pull request?
   
   Yes
   


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