ISSUE-140

Named Property Chains

POSTPONED: Allow (macro-like) shorthands for directly referring to property chains (instead of their superproperty)

State:

CLOSED

Product:

Raised by:

Rinke Hoekstra

Opened on:

2008-08-14

Description:

(issue raised after discussion with Uli)

Property inclusion axioms are restricted to be the sub property of some other property. For instance:

a o b -> c

An equivalence between the chain and the super property would allow the definition of recursive, and thereby infinite chains, e.g.:

a o b = b

This is hard to reason with: an existential class restriction on b would force such an infinite chain. 

However, in many cases it is really useful to be able to point to the chain *directly*. (cf. Nick Drummond's OWLED paper on sequences, Boris' structured objects, and my own work). What this would allow us to do, is force the existence of a sequence of connected individuals by either having a value restriction, or an individual property assertion on the named property chain. We can already enforce a chain of fixed length using nested class restrictions, however these are not as flexible as named property chains (reusability, ABox assertions, substitution in other property chains etc.).

Such named property chain would be a kind of 'macro property chain' so that you can write

'hasUncle some Rich'

and

'hasUncle shortfor  hasParent o hasBrother'


Uli says:
This should be harmless since it can simply be handled through preprocessing and macroexpansion.

A restriction is that these 'macro definitions' should be acyclic: then we can reduce ontologies with macros through expansion (i.e., exhaustively replace macros in value restrictions with their definitions) to ontologies without them.

Impact assessment: 
It would mean touching numerous documents, making sure that, e.g., each macros is defined not more than once in an ontology, etc...

Addendum: no number restrictions, the global restrictions for complex properties apply

Related Actions Items:

No related actions

Related emails:

1. Re: Agenda TC 24/09/2008 (from pfps@research.bell-labs.com on 2008-09-23)
2. Issue-140: Proposal to postpone (from ian.horrocks@comlab.ox.ac.uk on 2008-09-15)
3. Re: ISSUE-140 (Named Property Chains): Allow (macro-like) shorthands for directly referring to property chains (instead of their superproperty) (from hoekstra@uva.nl on 2008-08-14)
4. ISSUE-140 (Named Property Chains): Allow (macro-like) shorthands for directly referring to property chains (instead of their superproperty) (from sysbot+tracker@w3.org on 2008-08-14)

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