Re: SKOS transitive hierarchical relations

On Fri, Jan 6, 2012 at 10:08 AM, Christophe Dupriez <
christophe.dupriez@destin.be> wrote:

>  I said that if you have ALL the possible broaderTransitive, then you
> should be able to sort the paths (remove the "shortcuts") and retrieve only
> the true simple "broaders".
>

It depends on what you mean by *true*, *simple*, and *broader *; under
closed domains, either explicit  (i.e. if the set of concepts is explicitly
closed by asserted axioms, or  implicit (e.g. through completion under
Negation As Failure); and if there are no redundant desired broader
relationships, then

(if (not
       (exists Z
         (known (and  (broaderTransitive A Z) (broaderTransitive Z B)))))
    (broader A B))

This is transparent to poly-hierarchy.

This is similar to the semantics of broader matches , which are made to
concepts in different  concept schemes, which entail the non-existence of
any terms in the target concept scheme which is narrower than the term to
which the source term is related, but is still a broader match of the
source term; that is, the broader match is a least upper bound.

The problem with asserting broader and inferring broaderTransitive is that
SKOS does not require that broader semantics be transitive.  Thus, unless
the vocabulary creator asserts broaderTransitive, it is impossible to
determine whether the vocabulary creator believes it.

Simon