Proceedings of the Ninth International Workshop on Constraint Handling Rules September 4 th , 2012 Budapest , Hungary

This volume contains the papers presented at CHR 2012, the 9th International Workshop on Constraint Handling Rules held on September 4th, 2012 in Budapest, at the occasion of ICLP 2012. This workshop was the ninth in a series of annual CHR workshops. It means to bring together in an informal setting, people involved in research on all matters involving CHR, in order to promote the exchange of ideas and feedback on recent developments. Previous workshops on Constraint Handling Rules were organized in 2004 in Ulm (Germany), in 2005 in Sitges (Spain) at ICLP, in 2006 in Venice (Italy) at ICALP, in 2007 in Porto (Portgual) at ICLP, in 2008 in Hagenberg (Austria) at RTA, in 2009 in Pasadena (California, USA) at ICLP, in 2010 in Edinburgh (Scotland) at ICLP, and in 2011 in Cairo (Egypt) at the second CHR summer school.