[Top] [All Lists]

Re: [ontolog-forum] CL, CG, IKL and the relationship between symbols in

To: "John Black" <JohnBlack@xxxxxxxxxxx>
Cc: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Mon, 24 Dec 2007 23:23:34 -0800
Message-id: <p06230906c39658d0bd36@[]>
>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
>>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.    (01)

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.    (02)

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.    (03)

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.)    (04)

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.    (05)

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.)    (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    (07)

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.    (08)

>, not that the name will necessarily have the same referent in all 
>interpretations.    (09)

Not that, no. In fact that isn't even meaningful, since the universes 
of two interpretations may be disjoint.    (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'".
>>>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.....    (011)

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.    (012)

>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...."    (013)

"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.    (014)

Pat    (015)

>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
>>Better say, in *a* universe of discourse. There is one universe for 
>>each interpretation, and there may be many equally correct 
>>>, 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
>>>Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/ 
>>>Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
>>>Shared Files: http://ontolog.cim3.net/file/
>>>Community Wiki: http://ontolog.cim3.net/wiki/
>>>To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx
>>IHMC (850)434 8903 or (650)494 3973   home
>>40 South Alcaniz St. (850)202 4416   office
>>Pensacola (850)202 4440   fax
>>FL 32502 (850)291 0667    cell
>>phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes    (016)

IHMC            (850)434 8903 or (650)494 3973   home
40 South Alcaniz St.    (850)202 4416   office
Pensacola                       (850)202 4440   fax
FL 32502                        (850)291 0667    cell
phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes    (017)

Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/  
Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/  
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/ 
To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx    (018)

<Prev in Thread] Current Thread [Next in Thread>