Logic Colloquium '80

The papers appearing in this volume are part of those originally intended for presentation at the conference: Logic Colloquium '80 - European Summer Meeting of the Association for Symbolic Logic (A.S.L.) which was to takeplace in Prague, August 24·30, 1980, principally under the auspices of the Czech Academy of Sciences. There were 36 invited speakers from Western and Eastern Europe, Israel, the U.S., and the U.S.S.R. The local organizingcommittee cabled participants on July 15, 1980 to inform t