FM 93-3 mp_arc 93-172 Author: Giovanni Gallavotti Title: Twistless KAM tori Keywords: KAM theorem, invariant tori, classical mechanics, perturbation theory, chaos Abstract: A selfcontained proof of the KAM theorem in the Thirring model is discussed. Fisica, Universita' di Roma La Sapienza, P.le Moro 2, 00185, Roma, Italia. e-mail giovanni@ipparco.roma1.infn.it tel. 6-49914370, fax 6-4957697