Re: Modal predication vs reification

TL;DR:  RDF is so weak that everything has to be shoehorned into resources and 
predications in a single interpretation.  Discussions that mention anything 
else need to be couched in a well-specified extension to RDF.  It is possible 
to shoehorn many predicates, including :believes, :is-told-that, :place-of, 
and :instrument into RDF as it currently stands.



RDF has a strict distinction (based on RDF interpretations) between resources, 
e.g., what :messi denotes, and predications, e.g., what :messi :scores 
:last-WC22-goal denotes.  The former are entities in the world and can 
participate in predications. The latter carry the notion of truth and cannot 
be further elaborated, i.e., predications do not get to have properties as 
they can in most versions of property graphs.

If RDF-star is going to provide a meaning for embedded triples there are two 
options that I see.  The simple option is to make embedded triples be 
resources.  The complex option is to add a new kind of thing to the semantics 
of RDF.  I prefer the simple option, and a simple version of the simple 
option.  Anyone who wants to argue that a new kind of thing needs to be added 
to the semantics of RDF needs to come up with a firm account of how that new 
kind of thing works.  Any arguments about how to handle embedded triples that 
require a new kind of thing in the RDF semantics but that don't say how this 
new kind of thing works are impossible to analyze.

Arguments that the predicate :believes needs a "modal world" in RDF without 
saying how modal worlds work in RDF is in a similar quandary.  How am I to 
analyze whether this is the right way to go without such an account?


My take on :believes, :is-told-that, :stated, :place-of, and :instrument in 
RDF is that they can all be regular RDF properties.  Indeed there is no other 
choice if they are to be modelled in RDF as it currently stands.  Whether 
their objects are embedded triples depends on the predicate and the intended 
meaning of embedded triples.   Because of their quasi-uniqueness, embedded 
triples cannot represent statings and thus are not suitable as objects for 
:stated and maybe :is-told-that.  Whether :place-of and :instrument take 
embedded triples as objects depends on some subtle representation decisions, 
including the relationship between an embedded triple and the relationship is 
corresponds to.  (One might want embedded triples to correspond to some sort 
of inherent truth, in which case they are suitable objects for relationships 
like :place-of; on the other hand one might want embedded triples to be 
separate from inherent truth, in which case there could be many :place-of 
relationships that one would want to represent so there needs to be an 
intermediate resource to keep them separated from each other.)


peter



PS:  Just because something can be shoehorned into RDF does not imply that it 
is a good idea to do so.

Received on Thursday, 22 December 2022 18:14:25 UTC