- From: pat hayes <phayes@ai.uwf.edu>
- Date: Tue, 11 Feb 2003 18:01:21 -0600
- To: www-rdf-comments@w3.org
- Cc: bwm@hplb.hpl.hp.com, Jan.Grant@bristol.ac.uk
The current design of RDF literals is needlessly complicated and kind of silly. The syntax allows language tags to occur in typed literals, but in all cases other than rdf:XMLLiteral, these tags are required to have no meaning, so the semantics is obliged to provide a valid inference rule which allows any language tag in any such typed literal to be removed or replaced by any other. This considerably complicates the statement of the semantics, adds a burden to any implementation, nullifies the implicit design principle that literals can be compared for identity using simple lexical matching (since an engine is required to strip out all such lang tags while performing inferences or checking for identity), and provides no useful expressive function. A related point is that the requirement in the semantics that datatypes other than rdf:XMLLiteral *must* ignore language tags seems to restrict possible future datatyping proposals needlessly. I suggest therefore that EITHER (1) lang tags be forbidden by the RDF syntax from appearing in non-XML typed literals. OR ELSE (2) the notion of the lexical space of a datatype be generalized to allow (not require) lang tags to be taken into consideration by a datatype, so that the lexical space may be a set of strings or pairs of strings, i.e. a set of simple literals. This would have the effect that it would no longer be valid to make arbitrary changes to a lang tag in any literal, typed or not. It would also bring the treatment of all RDF datatypes into alignment so that rdf:XMLLiteral need not be considered a special case. Either of these changes will simplify the semantics and make it more coherent, but in slightly different ways. Either change will produce fewer inference rules and lead to less processing in a reasoning engine. Pat Hayes -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32501 (850)291 0667 cell phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes s.pam@ai.uwf.edu for spam
Received on Tuesday, 11 February 2003 19:01:25 UTC