  We propose a recipe to construct the DLCQ Hamiltonian of type IIB string
theory on the AdS (and/or plane-wave) background. We consider a system of J
number of coincident unstable non-BPS D0-branes of IIB theory in the light-cone
gauge and on the plane-wave background with a compact null direction, the
dynamics of which is described by the world-line U(J) gauge theory. This
configuration suffers from tachyonic instabilities. Having instabilities been
cured through the process of open string tachyon condensation, by expanding the
theory about true minima of the effective potential and furthermore taking low
energy limit to decouple the heavy modes, we end up with a 0+1-dimensional
supersymmetric U(J) gauge theory, a Matrix Theory. We conjecture that the
Hamiltonian of this Matrix Theory is just the DLCQ Hamiltonian of type IIB
string theory on the AdS or equivalently plane-wave background in a sector with
J units of light-cone momentum. We present some pieces of evidence in support
of the proposal.
