Duality and light cone symmetries of the equations of motion

The matrix theory description of the discrete light cone quantization of M theory on a T2 is studied. In terms of its super Yang-Mills description, we identify symmetries of the equations of motion corresponding to independent rescalings of one of the world sheet light cone coordinates, which show how the S duality of Type IIB string theory is realized as a Nahm-type transformation. In the M theory description this corresponds to a simple 9−11 flip.