 Readers interested in the mathematical substance of learning theory will find some references in the  Bibliography,  and a summary of the basic definitions in the  Supplementary Document.  A text by Jain et al. collects many of the main definitions and theorems [1999]. New results appear in proceedings of annual conferences, such as the Conferences on Learning Theory (COLT) and Algorithmic Learning Theory (ALT). The philosophical issues and motivation pertaining to learning-theoretic epistemology are discussed extensively in the works of philosophers such as Putnam, Glymour and Kelly (Putnam [1963], Glymour [1991], Glymour and Kelly [1992], Kelly [1996]).