Hi John and all,
I missed the beginning of this form and content discussion, but I think
it is important in answering some questions relevant to NLP.
The distinction between form and content
depends on what you consider form and what you consider content. Clear
definitions of what constitutes form, and what comprises content, are missing.
If I use punctuators as background, I get interesting
content from _expression_ number 1:
A [ j, k ] := 389,201.32;
And the signature of that _expression_ is:
_[_,_]:=N,N.N;
The next _expression_, number 2:
B [ r, q] := 0;
Has a signature
_[_,_]:=N;
Which is a left hand subsignature of _expression_ 1.
There is a modest analogy in those patterns to context free grammars, and to
the dictionary morphological keys used in the link grammar.
So one choice of background mapping leads to a whole set of signatures
that can have interesting relationships with each other.
But a different choice of background leads to a different conclusion.
If I use alphas as background so I can get some numeric and syntactic handle on
other parts of morphology, I can get entirely different signatures.
If I use alphas as background, I get interesting
content from _expression_ number 1:
A [ j, k ] := 389,201.32;
And the signature of that _expression_ is:
_[_,_]:=289,201.32;
The next _expression_, number 2:
B [ r, q] := 0;
Has a signature
_[_,_]:=0;
This is NOT a left hand subsignature of _expression_ 1
because “0” doesn’t match with “2”. But the
first eight signature characters can match both _expression_ 1 and 2:
_[_,]:= is a
valid left hand signature of both expressions 1 and 2.
The point I am trying to make here is that the choice between
foreground and background is better characterized as an art than a science –
highly subjective on the part of the observer. Only after the choice has
been made can the math be applied to the pattern set to get signatures that can
be processed.
-Rich
Sincerely,
Rich Cooper
EnglishLogicKernel.com
Rich AT EnglishLogicKernel DOT com
-----Original Message-----
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of John F. Sowa
Sent: Thursday, December 10, 2009 6:23 AM
To: [ontolog-forum]
Subject: [ontolog-forum] Form and content
Most people on this list understand the distinction between form
and content, but some discussions tend to blur the distinction.
I received an offline question related to that point, and I thought
it might be useful to forward the answer to the list.
John Sowa
___________________________________________________________________
> May I know what is the difference between semantic network
> and ontology?
A semantic network is a graphical form for knowledge representation.
It can be used to express content of any kind.
An ontology is a formal definition of content, which could be
represented in many different KR languages and notations.
The distinction between form and content is critical, but some
KR languages incorporate some ontology into the basic notation.
Therefore, they would combine some content with the form.
For example, a temporal logic is likely to have at least a minimal
ontology for time built into the notation and rules of inference.
A KR language that includes arithmetic will have an ontology for
numbers and operations on numbers built into the basic language.
Common Logic is a version of logic that is as neutral as possible
about ontology. For example, CL includes syntax for numerals, but
it does not assume any axioms about the integers represented by
those numerals. One application might represent integers of
arbitrary length, but another might have an upper limit of 2^63.
Some people have complained about the lack of an ontology for
numbers in CL. But there are many different ontologies that can
be added to CL as needed. One example is the Mathematical toolkit
in the ISO standard for Z notation. It's a fine ontology, it's
defined by an ISO standard, and anyone who wants it can use it
in conjunction with CL. But anybody who needs a different
ontology for numbers can use that instead.
John Sowa
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