“…The heterotic soliton construction of Harvey and Strominger, and of Sen, provides a map between target space duality symmetries of the IIA theory and corresponding transformations on the world-sheet fields of the heterotic compactification. Provided such a symmetry is freely acting, one expects the theories obtained by orbifolding to provide additional strong/weak dual pairs [7,15,16,17,18,19,[20][21]. Thus, from this duality alone one can derive a remarkable web of strong/weak dualities in dimensions six and below.…”