Yolanda Gil has announced
a useful
analysis of the differences and similarities of W3C XML Schema, RDF
Schema and DAML in the context of the
requirements of knowledge representation.
For each issue (such as contexts, inheritance, object classes) the table
explains how each of the languages implement (or do not implement) the
feature, and links to examples.
In a follow-up message to Gil's announcement, Oscar Corcho also provided
links to several papers he and Asunción Gómez-Pérez have written on
ontology specification languages.