This book constitutes the thoroughly refereed post-proceedings of the 2006 Pacific Rim Knowledge Acquisition Workshop, PKAW 2006, held in Guilin, China in August 2006 as part of 9th Pacific Rim International Conference on Artificial Intelligence, PRICAI 2006.

The 21 revised full papers and 6 revised short papers presented together with 4 invited talks were carefully reviewed and selected from 81 submissions. The papers are organized in topical sections on ontology and knowledge acquisition, algorithm approaches to knowledge acquisition, incremental knowledge acquisition and RDR, knowledge acquisition and applications, as well as machine learning and data mining.

This volume contains the papers presented at the 8th International Conference onDiscoveryScience(DS2005)heldinSingapore, RepublicofSingapore, during the days from 8 11 of October 2005. The main objective of the Discovery Science (DS) conference series is to p- vide an open forum for intensive discussions and the exchange of new ideas and information among researchers working in the area of automating scienti?c d- covery or working on tools for supporting the human process of discovery in science. It has been a successful arrangement in the past to co-locate the DS conference with the International Conference on Algorithmic Learning Theory (ALT). This combination of ALT and DS allows for a comprehensive treatment ofthewholerange, fromtheoreticalinvestigationstopracticalapplications.C- tinuing in this tradition, DS 2005 was co-located with the 16th ALT conference (ALT2005).TheproceedingsofALT 2005werepublished asa twinvolume3734 of the LNCS series. TheInternationalSteeringCommitteeoftheDiscoveryScienceconference- ries providedimportantadviceon a number ofissues during the planning of D- coveryScience2005.ThemembersoftheSteeringCommiteeareHiroshiMotoda, (Osaka University), Alberto Apostolico (Purdue University), Setsuo Arikawa (Kyushu University), Achim Ho?mann (University of New South Wales), Klaus P. Jantke (DFKI and FIT Leipzig, Germany), Massimo Melucci (U- versityofPadua), Masahiko Sato(Kyoto University), Ayumi Shinohara(Tohoku University), EinoshinSuzuki(YokohamaNationalUniversity), andThomasZe- mann (Hokkaido University). We received 112 full paper submissions out of which 21 long papers (up to 15 pages), 7 regular papers (up to 9 pages), and 9 project reports (3 pages) were acceptedforpresentationandarepublished inthis volume.Eachsubmissionwas reviewed by at least two members of the Program Committee of international expertsinthe?eld.Theselectionwasmadeaftercarefulevaluationofeachpaper based on originality, technical quality, relevance to the ?eld of discovery science, and clar