2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/54480In this article we examine the compatibility of some recent results, results relating M-Theory to String Theory, with the string-string duality conjecture in six-dimensions. In particular, we rederive the relation between M-Theory and Type IIA strings. We then go on to examine in detail M-Theory on $K3 \times S^{1}$ and its relation to the Heterotic theory on $T^{4}$. We conclude with some remarks on M-Theory on $T^{4}\times (S^{1}/{\bf Z}_{2})$ and its relation to the Type II theory on $K3$.28 Pages, Uses harvmac.texHigh Energy Physics - TheoryM-Theory and String-String Dualitytext