# Re: Reification as nesting

From: Drew McDermott <drew.mcdermott@yale.edu>
Date: Thu, 7 Jun 2001 11:28:25 -0400 (EDT)
Message-Id: <200106071528.f57FSOs03213@pantheon-po03.its.yale.edu>

```
[tim]
>Agreed.  One should be careful one doesn't suggest that htere are two types
>of things, a "triple" and an "assertion". They are the same thing.

[pat]
I'm suggesting that they are not the same: that is the point. Not all
triples are asserted (or even assertable.) Some assertions are
totally comprised by a single simple SVO triple which doesnt contain
any others,  but other assertions assert things that require a larger
structure, made up of a number of triples, to represent them. Those
triples that make up that larger thing are not assertions.

There are two issues here that shouldn't be conflated: (1) Is an
assertion syntactically different from a proposition, or just a
proposition as asserted by some agent?  (2) Are some proposition-like
formulas too syntactically incomplete to be assertable?

The answer to (1) is, No, assertions are just asserted propositions.

The answer to (2) is, Yes, some "propositions" can't be asserted
unless they appear in the right context.  The obvious example (which I
think Pat discusses) is variables.  This is an issue that's become
fairly urgent.  Jonathan Borden suggests making variables be a known
syntactic category, so that RDF processors know when they see a
variable even if they don't know what to do with it.  So in a statement
like

[?x, Forall,
{[{[?x rdf:type Crow]}
rdf:implies
{[?x color black]}]}]

the innermost triples qualify as propositions only when some sort of
binding of ?x is provided.

[By the way, I apologize for my crude N3-ish style of writing these
things.  I need to go back and review N3 now that we have a nice way
of interpreting braces.]

-- Drew McDermott
```
Received on Thursday, 7 June 2001 11:28:30 GMT

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