Ron Artstein Sudeep Gandhe Jillian Gerten Anton Leuski David R. Traum Semi-formal Evaluation of Conversational Characters. 22-35 2009 Languages: From Formal to Natural http://dx.doi.org/10.1007/978-3-642-01748-3_2 conf/birthday/2009francez db/conf/birthday/francez2009.html#ArtsteinGGLT09