Constraint programming supports a great ambition for computer programming: the one of making programming essentially a modeling task, with equations, constraints, and logicalformulas. This ?eld emerged in the mid-1980sborrowing conceptsfromlogicprogramming, operationsresearch, andarti?cialintelligence. Its foundation is the use of relations on mathematical variables to compute with partial information systems. The successes of constraint programming for so- ing combinatorial optimization problems in industry or commerce are related to the advances made in the ?eld on new constraint propagationtechniques and on declarativelanguageswhich allowcontrolonthe mixing of heterogeneousreso- tiontechniquessuchasnumerical, symbolic, deductive, andheuristictechniques. This volumecontainsthe papers selectedfor the post-proceedingsof the12th International Workshop on Constraint Solving and Constraint Logic Progr- ming (CSCLP 2007) held during June 7-8, 2008 in Rocquencourt, France. This workshop, open to all, was organized as the 12th meeting of the working group onConstraintsofthe EuropeanResearchConsortiumfor Informaticsand Ma- ematics (ERCIM), continuing a series of workshops organized since the creation of the working group in 1997. A selection of papers of these annual workshops have been published since 2002 in a series of books which illustrate the evo- tion of the ?eld, under the title "Recent Advances in Constraints"in the Lecture Notes in Arti?cial Intelligence series. This year, there were 16 submissions, most of them being extended and - vised versions of papers presented at the workshop, plus some new papers. Each submission was reviewed by three reviewers. The Program Committee decided to accept ten papers for publication in this book.

The promise of the Semantic Web is to move from a Web of data to a Web of meaning and distributed services. This vision of the Web has attracted - searchersfromdi?erent horizonswith the aims of de?ning newarchitecturesand languages necessary to make it possible, and of developing the ?rst applications of these concepts. This book contains the articles selected for publication and presentation at the workshop "Principles and Practice of Semantic Web Reasoning" PPSWR 2005, together with three invited talks. Three major aspects of Semantic Web research are represented in this selection: architecture issues, language issues, and reasoning methods. These advances are investigated in the context of new design principles and challenging applications. ThePPSWR2005workshopwaspartoftheDagstuhlseminarontheSem- tic Web organizedby F. Bry (Univ. Munchen, Germany),F. Fages (INRIA Roc- .. quencourt, France), M. Marchiori (MIT, Cambridge, USA) and H.-J. Ohlbach (Univ. Munchen, Germany),held in Dagstuhl, Germany,11-16September 2005...It was supported by the European Network of Excellence REWERSE (Reas- ing on the Web with Rules and Semantics, http://rewerse.net). This four-year project includes 27 European research and development organizations, and is intended to bolster Europe's expertise in Web reasoning systems and appli- tions.Itconsistsofeightmainworkinggroups:"RuleMarkupLanguage","Policy Language, Enforcement, Composition","Composition and Typing","Reasoning- Aware Querying","Evolution","Time and Location","Adding Semantics to the Bioinformatics Web", and "Personalized Information Systems". The papers in this volume re?ect most of the topics investigated in REWERSE; one third of them come from outside REWERSE.