EQUIVALENCE OF DUAL FIELD THEORETICAL LIMITS OF SUPERSTRING THEORIES

The equivalence of type IA and type IB field theoretical limits of su-perstring theories is shown by using a new type of duality transformation. Compactifications of the type IB theory to four dimensions are studied and it is shown that they induce the same vacuum configurations as the type IA theory provided the field equations are satisfied. * Research supported by U. S. Department of Energy Contract No. DE-AC02-76ER02220. 1. Introduction. Superstring theories [1] are presently considered as promising candidates for the unifica-tion of all fundamental interactions. They provide a framework which is free of perturbative ultraviolet divergences and gauge, gravitational and mixed anomalies [2,3]. Furthermore, recent work has shown that their low energy spectrum consists of chiral matter fields in