Re: Syntax and semantics

At 01:30 PM 5/16/00 -0500, Paul Prescod wrote:

>  * In what sense does XML not have semantics? Isn't the interpretation
>of less-than symbols and ampersands as an annotated, tree-structured,
>information set the "semantic content" of XML? Can any useful language,
>or meta-language, or meta-meta-language be entirely devoid of semantics?

I suspect that the term "semantics" is used differently by different 
people. I understand the relationship between tokens, structure, and 
semantics pretty much the way Dick Grune described it in his "Parsing 
Techniques, A Practical Guide":

<Quote>
To the computer scientist, a language is a probably infinitely large set of 
sentences,
each composed of tokens in such a way that it has structure; the tokens and the
structure cooperate to describe the semantics of the sentence, its 
"meaning" if you will.
Both the structure and the semantics are new, that is, were not present in 
the formal
model, and it is his responsibility to provide and manipulate them both. To 
a computer
scientist 3+4*5 is a sentence in the language of "arithmetics on single 
digits" ("single
digits" to avoid having an infinite number of symbols), its structure can 
be shown, for
instance, by inserting parentheses: (3+(4*5)) and its semantics is probably 23.
</Quote>

To me, namespaces are used to disambiguate names, and are used in the 
process of tokenizing. XML DTDs or schemas determine which sentences are 
legal and describe the structure of those sentences. Semantics are not 
contained in XML per se, but in systems that use XML, including RDF, but 
also including many of the everyday programs that munch XML.

Jonathan

Received on Tuesday, 16 May 2000 14:44:45 UTC