on Tue. Dec. 25, 2007 at 2:23 AM, Pat Hayes wrote:
>
> >on Mon Dec 24, 2007 at 4:18 PM, Pat Hayes wrote:
>>
>>> >Please forgive me, in advance, for my spotty knowledge of some of the
>>> >topics
>>>>in this post. My interest in these ideas often exceeds my understanding.
>>>>
>>>>First, congratulations to all on the ISO adoption of CL as a standard. I
>>>>believe it will prove to be an invaluable addition to the spread of
>>>>interoperable knowledge representation technology. It is an important
>>>>achievement. I am doubly excited by this because it includes, at long
>>>>last,
>>>>an ISO standard for Conceptual Graphs. CGs was the first knowledge
>>>>representation formalism I encountered. I read the CG1984 book several
>>>>times, worked on an implementation in prolog of a linear form, and then
>>>>had
>>>>the pleasure to participate for a short time in 1997 on work towards the
>>>>CGIF standard specification. More recently, having decided that
>>>>semantics is
>>>>heavily dependent on contexts, and searching for material concerning
>>>>that
>>>>subject, I came across IKL and the startling claim that "Every
>>>>occurrence of
>>>>an IKL name has the same meaning." This is something I find highly
>>>>desirable, but which as I said, I had just recently decided was not
>>>>possible.
>>>
>>>I think you may be reading more into this than was intended. It does not
>>>say that every occurrence of an IKL name has the same unique referent in
>>>the actual world. It says that every such name occurrence maps to
>>>referents in all interpretations in the same way. But there may be many
>>>possible interpretations: there almost always are.
>>
>>I'm confused. I understand that there may be many interpretations. Lets
>>consider the case of two network nodes. If the referent of a name 'A' is X
>>in one interpretation and is Y in another interpretation, then in what
>>sense are these name occurrences mapped "...in the same way."? From what
>>you say later, I suppose you mean that all the same statements are true of
>>both X and Y.
>
> Yes, quite correct. What that puzzling phrase means is only that the WAY
> that the interpretation mappings are applied is uniform across all
> occurrences of names. To see what this means, consider some cases where
> this would fail to be true.
>
> 1. If the logic has modalities such a a future tense operator F, then the
> meaning of a name (in fact, any referring term) may be different inside
> the scope of the modality from its meaning outside. Suppose for example we
> introduce a name [note A] PresidentOfUSA, so that (= PresidentOfUSA
> GeorgeWBush) is true now; but it is certainly not true now that (F 2010 (=
> PresidentOfUSA GeorgeWBush)), because the referent of "PresidentOf USA"
> will be different in 2010.
>
> 2. If the logic has contexts which affect the denotation of names, then
> the same name may be interpreted differently in different contexts. (Not
> all context logics allow names to denote differently in this way, but some
> do.) (01)
And this is clearly a part of IKL. Is the modality and context logic mapping
functionality in IKL due to something in CL? Or is this part of the IKL
dialect? A related question: Is IKL considered to be an ISO standard by
virtue of its being conformant to the CL dialect forming feature in CL? Or
will it need to go through a standardization process also? (02)
> 3. If the logic is used to encode temporally sensitive data, then what a
> name denotes can change with actual time, so that archived information may
> contain names which now no longer denote what their 'current' values are. (03)
I had thought that time was yet another type of context. Is it different
somehow? (04)
> 4. If the same name is used in several ontologies widely separated or
> built independently using a conventional FOL syntax or OWL-DL, then one of
> them might use it to name an individual, while another might use it to
> name a relation (in FOL) or a class (in OWL-DL), producing a syntactically
> illegal situation when these ontologies are merged, since these logics
> require names to be strictly segregated according to what they are allowed
> to denote. (This situation, and finding a uniform way to avoid it, was one
> of the leading motivations for the CL design, in fact.) (05)
Do you mean that CL has features which allows these illegal situations to be
dealt with post-hoc or is this something that must be done up front using CL
cooperatively? It looks to me like what is done is that CL allows for both
ontologies to be translated to CL and then merged legally. This would still
leave work to be done to make the two groups of sentences work together,
wouldn't it? (06)
>>
>>>>The topic I am particularly interested in discussing here now, is this
>>>>claim
>>>>and a similar statement in the CL requirements section 5.1.4.b., "Any
>>>>piece
>>>>of Common Logic text should have the same meaning, and support the same
>>>>entailments everywhere on the network. Every name should have the same
>>>>logical meaning at every node of the network."
>>>
>>>Right. Note, *logical* meaning. One might reasonably say that the meaning
>>>of "Patrick J Hayes" is me, in this particular world, but that is not its
>>>logical meaning. Its logical meaning is a mapping from interpretations
>>>(aka possible worlds) to an individual in that interpretation's universe.
>>
>>I have never gotten comfortable with the idea of sorts or types of meaning
>>(formal, social, natural, logical, etc. etc.). Never-the-less, I take you
>>mean that the requirement is that the same set of statements will be true
>>of all referents of the name in all interpretations
>
> Yes. And of every *occurrence* of the name, is the point. CL and IKL treat
> every *occurrence* of a name in the same way, wherever it occurs. Many
> logics do not. In fact, most logics do not. (07)
So we would say, "...the same set of statements will be true of all
referents of each occurrence of the name in all interpretations."? Then you
are saying that most logics treat the separate occurrences of a name as
though there were only one occurrence? Reminds me of a question I keep
having with regard to URIs in the Web Architecture. There doesn't seem to be
any attempt to distinguish between each occurrence (I sometimes call it an
utterance) of a URI and its establishment. And in fact, it seems to be
argued often that this is by design and intentional, yet nowhere is are
there methods for dealing with what seems to be inevitable contextual
differences between each occurrence of a URI. In other words, it sounds like
IKL aims for the same goal but includes some machinery for achieving it,
while the Web Architecture claims that it is so by engineering design. Fair
characterization? (08)
>>, not that the name will necessarily have the same referent in all
>>interpretations.
>
> Not that, no. In fact that isn't even meaningful, since the universes of
> two interpretations may be disjoint. (09)
But then what do other logics claim? How do they put it? You said before
that most logics do not treat each occurrence of a name differently. (010)
>> Is that right? This is quite a different result from what I was reading
>> it to say.
>>
>>>> Yet in the version of the
>>>>Common Logic (CL) specification I have, in section 1 I read "The
>>>>following
>>>>are outside the scope of this standard: ... Computer-based operational
>>>>methods of providing relationships between symbols in the logical
>>>>'universe
>>>>of discourse' and individuals in the 'real world'".
>>>
>>>Right.
>>>
>>>>
>>>>This topic, the operational relationship between symbols in logic and
>>>>individuals in the world, happens to be my particular interest of late.
>>>>Actually, come to think of it, I have been interested in this for some
>>>>time
>>>
>>>Join the club :-) Seriously, this is a very large and interesting topic.
>>>One has to recognize, however, that it goes beyond the scope of logic as
>>>usually construed: certainly beyond the scope of Tarskian logical
>>>semantics.
>>>
>>>>and I recall that one of the many things that impressed me about John
>>>>Sowa's
>>>>first book on Conceptual Structures in 1984 was the chapter on
>>>>Psychological
>>>>Evidence, including the discussion of perceptrons.
>>>
>>>Perceptrons or perceptions? Perceptrons were a very early idea in what is
>>>now called neural networks.
>>
>>My mistake - two in fact - very embarrassing!
>>The term used was "percepts", not "perceptrons" and it is found in chapter
>>3 titled "Conceptual Graphs" not in chapter 2, "Psychological Evidence".
>>
>>>>That section was, at
>>>>least an initial attempt, to address the question.
>>>
>>>? How does a perceptron (or a neural network more generally) address the
>>>question of how names come to be attached to their referents? I see no
>>>connection at all.
>>
>>Right, my error, see previous section. He uses "percepts" differently, in
>>terms of neuroscience rather than neural networks. In section 3.1
>>"Percepts and Concepts" of Chapter 3, he says "For concrete entities like
>>cats and tomatoes, the brain has percepts for recognizing the entity and
>>concepts for thinking about it.....
>
> Ah, I see. Well, to be strict about it for a second, nobody really knows
> how the brain does what it does, but the idea that it somehow represents
> internally information about the way things look seems to be widely
> accepted. Its not at all obvious that there is a sharp distinction between
> recognition and thinking about in these cases, however: and of course
> there are many notions we have that don't correspond to anything apparent
> to our senses at all.
>
>>3.1.3 Assumption. For every percept p, there is a concept c, called the
>>interpretation of p. the percept p is called the image of c. Some concepts
>>have no images...."
>
> "Mental images" is a black hole which I'd rather not go down. There is a
> huge body of work now on this, and about as large a body of controversy
> about what the empirical results actually mean. I don't think we need to
> get involved with all this here: it has no direct bearing on the questions
> of reference. I know what "Sweden" refers to, but I've never seen even a
> part of Sweden, and I doubt if I could ever see Sweden itself, even from a
> stable orbit.
>
>
> Pat
>
>>
>>That there is something which aids the recognition of an entity (referent)
>>which a (named) concept is about - that is the connection I see.
>>
>>John Black
>>
>>>>So here is my first question: If the semantics of CL starts out with a
>>>>mapping from the vocabulary of a CL text to individuals in the universe
>>>>of
>>>>discourse
>>>
>>>Better say, in *a* universe of discourse. There is one universe for each
>>>interpretation, and there may be many equally correct interpretations.
>>>
>>>>, but this mapping is nowhere encoded or included in the CL text
>>>
>>>It cannot be encoded in text, being a mapping from text to what may well
>>>be non-textual things.
>>>
>>>>,
>>>>then how can you be sure that one agents mapping to individuals at one
>>>>node
>>>>of the network will be the same as the mapping of another agent at some
>>>>other node of the network?
>>>
>>>You can't. The best you can do is to be sure that all the possible
>>>mappings that are consistent (using that word informally) with the
>>>conclusions that the second agent can draw, are also consistent with
>>>those that the originating agent can draw. That is a (rather convoluted)
>>>way of saying that they are both using the same logic and both respecting
>>>the notion of entailment that is supports. This is the best that any
>>>logical semantics can possibly guarantee.
>>>
>>>Pat Hayes
>>>
>>>>
>>>>John Black
>>>>www.kashori.com
>>>>
>>>>
>>>>
>>>>
>>>>
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>>>
>>>
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>
>
> --
> ---------------------------------------------------------------------
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