The Semantic Web is a worldwide endeavor to advance the Web by enriching
its content with semantic metainformation that can be processed by
inferen- enabled Web applications. Taxonomies and rules, along with
their automated reasoning techniques, are the main components of
Semantic Web ontologies. Rule systems are considered to be a major area
in the further development of the Semantic Web. On one hand, rules can
specify declarative knowledge in ontology languages, expressing
constraints or transformations, either in conju- tionwith,
orasanalternativeto, descriptionlogics.Ontheotherhand, rulescan specify
behavioral knowledge, enforcing policies or reacting to events/changes.
Finally, rule markup languages such as RuleML allow us to publish rules
on the Web, to process rules in general XML environments as well as
special rule engines, to exchange rules between di?erent applications
and tools via XSLT translators, as well as to embed rules into other XML
content and vice versa. This workshop was dedicated to all aspects of
rules and rule markup l- guages for the Semantic Web. RuleML 2004 was
the third in a series of wo- shops that was initiated with the
International Semantic Web Conference. The previous workshops were held
on Sardinia, Italy (2002), and on Sanibel Island, USA (2003).
Thisyearwehad25submissions, ofwhich11wereacceptedasregularpapers and
another ?ve as short papers describing tools.
Wearegratefultoourtwoinvitedspeakers, MikeDeanfromBBNandChr- tine
Golbreich from the University of Rennes. Our thanks also go to all subm-
ters and reviewers without whom the workshop and these proceedings could
not have succeeded.