> Anyway, these rules take quite a long time (about 90 seconds) to execute on 
> my OWL_MEM model, which isn't all that big at about 3000 triples including 
> all the imported models.  Does that sound plausible?  If so, I'm thinking I 
> may need to add these inferences in a more targeted way.

In general, as you certainly know, the performance of SPARQL queries strongly 
depends on the implementation of the engine and whether (or not) it re-orders 
clauses automatically. It is best to assume that ARQ will execute the clauses 
(triple matches and filters) from top to bottom, but looking at the SPARQL 
Debugger in TBC will help you identify the real execution order. In particular 
FILTER clauses may be re-ordered with significant performance penalty. There is 
a new option in TBC on the SPARQL preferences tab to force ARQ to leave the 
FILTER clauses in place, which is IMHO recommended.

In SPIN in particular, other factors are important:
- if a class has many subclasses with instances, then there might be many 
individual SPARQL calls for each rule defined on the superclasses.
- Each iteration will have a clause to bind ?this with all instances of a class.

If these cause performance issues, you can bypass the binding of ?this by either
- making rules global (drop ?this and instead put them at owl:Thing or 
rdfs:Resource) These global rules will be executed only once
- use the new SPIN 1.1 property spin:thisUnbound to drop the ?this rdf:type 
<class> clause, which may theoretically slow down

After you run inferences in TBC, the Error Log will contain a list of the 
slowest queries, together with benchmarks.

I hope this helps... let me know if you have ideas on how to improve 
performance tuning.

Regards,
Holger

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