[Person-ontology] D7 - Which languages are better than OWL?
Pat Hayes
phayes at ihmc.us
Sun Dec 23 12:05:47 PST 2007
> Dear Philippe,
>
> Apparently, you have some problems in
>catching my central point, which is very simple.
>Independently then from any representational
>trick, from RDF to FCG or other, this point is
>that, in an n-ary situation
What do you mean by a n-ary *situation* ? The
situation being described has no intrinsic
'arity' (a point made many years ago by, I
believe, Strawson), because one can go on adding
qualifiers endlessly (he did it... at midnight...
in the kitchen... last week... with a knife...
silently... rapidly...). In fact, this has been
used as an argument (to me, convincing) for the
naturalness of the binary case-based
representation over the use of n-ary relations.
>like that represented by the event "Mary has
>given a book to Bill", you are surely entitled
>to decompose this situation in a series of
>binary relationships, saying, e.g., that Mary is
>the subject of an action of giving but, in order
>to "understand" really this elementary event,
>you must necessarily merge again the single
>binary relationships in a global unit, (an n-ary
>one), and to work on this in a global way.
This sounds like CSPeirce reprise. The problem I
have with claims like this is that they are so
vague that they don't mean anything. Words like
""understand"" (with scare quotes) and "global"
have no bearing on any precise semantic theory
that I know of. They seem to be vaguely
philosophical rhetoric. Now, maybe (in your
forthcoming book?) you do have a semantic theory
which makes them have some more precise content.
If so, can you summarize this for us, briefly?
>If you deal with the elementary binary
>relationships separately (this is what the W3C
>languages allow at the moment), it is difficult
>you will ever be able to move beyond the
>inferences of the "uncle" type the SWRL's
>supporters are fond of.
One can show quite rigorously that the
translation into a binary framework is what one
might call entailment-complete: that is, if P is
a set of sentences written using n-ary relations
and t(P) is the translation of P into the binary
relationships and existential quantifiers (the
'case-based' representation familiar for at least
40, and probably more like 140, years) then if P
entails Q then t(P) entails t(Q). The reverse is
not true, since there are consequences of the
translations (such as the existence of the
'tropes' or n-ary facts as objects) which do not
follow from the original.
> In NKRL, an event like the above is
>represented as an instance of a general, n-ary
>"template" of the type
>"Move:TransferMaterialThingToSomeone", which is
>a specialization of a "Move:TransferToSomeone"
>template. In the two templates (and in their
>instances) the semantic predicate is
>(conventionally) MOVE, and the slots SUBJ, OBJ
>and BENEFICIARY are necessarily filled
Why do you say this? One can often infer useful
things from incomplete information. It is quite
frequently the case that temporal information is
missing or incomplete, for example.
>; the other (MODAL, CONTEXT etc.) can be filled
>or not depending from the original formulation
>of the event. In the concrete instances, the
>temporal information must obviously be added.
>All the inferences are then executed starting
>from this unitary, n-ary block.
Perhaps you are describing a particular system;
but what you say here is certainly not true for
general inference of the kind supported by OWL or
a logical reasoning engine. And it does not apply
to whole categories of real applications (I am
particularly thinking of the kinds of reasoning
used by intelligence agencies).
>Note, moreover, that I have voluntarily chosen a
>particularly simple example, avoiding, e.g., to
>speak of "connectivity phenomena" in the style
>of "Mary has given a book to Bill BECAUSE it was
>Bill's birthday".
Seems to me that this kind of thing is actually
easier to express in the binary translation,
because the 'tropes' (facts, events,...) are
there reified into first-class objects which can
themselves take part in relationships and have
properties.
>
> There are some other strange statements in
>your mail, like "... the primitive notion here
>is the concept type Gift, not the relation types
>gift etc." (???)
Makes sense to me :-)
Pat Hayes
> but, as you suggest, I will reply, in case,
>separately (but only when my book will be
>finished).
>
> Regards,
>
> GPZ
>
>
>
>
><mailto:mail at PHILIPPEMARTIN.COM>mail at PHILIPPEMARTIN.COM wrote:
>
>>Dear Gian,
>>
>>
>>
>>>"a representation using an n-ary relation can always be converted
>>> to a representation using a binary relation, without loss of
>>> semantics" ... "without loss of semantics" is false.
>>>
>>>
>>
>>I was waiting/hoping for that feedback.
>>Unfortunately, I am missing the (fine) point(s) in both your
>>email and the article you cited:
>>1) Where is the loss of semantics when you translate
>> (giftOfSomethingBySomeoneToSomeoneSometime
>> book328 Mary128 Bill948 '12/9/2007')
>> into (I use the FCG notation here)
>> [a Gift, object: book328, agent: Mary128,
>> recipient: Bill948, date:12/9/2007]
>> or to [ [a Gift, object: book328, agent: Mary128,
>> recipient: Bill948], date: 12/9/2007]
>> I only see an increase of precision/semantic because
>> the roles have been explicited. As you acknowledge in
>> our article this decomposition avoids the combinatorial
>> explosion of relation types such as
>> giftOfSomethingBySomeoneToSomeoneSometime, which
>> furthermore cannot be ordered into a specialization
>> hierarchy (thus making knowledge re-use and comparison
>> difficult). I'd add the fact that you can quantify the
>> concept type 'Gift' (e.g., "2 Gift"or "any Gift") but not
>> the previous relation type. Hence, I think the primitive
>> notion here is the concept type Gift here, not the relation
>> types gift or giftOfSomethingBySomeoneToSomeoneSometime.
>>2) At the end of page 3 of your article, you hint at the
>> n-ary nature of the anonymously referred situation instance
>> (in my above example, the particular gift , say,
>> gift739ofSomeBookFromMary128ToBill948AtDate12/9/2007).
>> I personally see this instance as an instance of the
>> concept type Gift, not as an instance of an n-ary relationship
>> but, in any case, what are the consequences (where is the
>> loss of semantics)?
>>3) what are these inferences that must "NECESSARILY" be made in NKRL
>> even though NKRL can be fully translated from and to RDF?
>> (I actually only saw binary relations in the NKRL examples
>> of your article but I admit I have not yet read Section 3
>> in detail). Please use an example, preferably using KIF or FCG.
>>
>>Given we are here departing a bit from the core goal of D7, it might
>>be better to answer to me directly and I'll then post a summary of
>>the underlying ideas in my structured format (when I understand
>>these ideas enough to give a good summary). I let you be judge.
>>
>>Philippe
>>
>>
>>
>
>
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