We present a novel differential-difference system in (2+1)-dimensional
space-time (one discrete, two continuum), arisen from the Bogoyavlensky's
(2+1)-dimensional KdV hierarchy. Our method is based on the bilinear identity
of the hierarchy, which is related to the vertex operator representation of the
toroidal Lie algebra \sl_2^{tor}.Comment: 10 pages, 4 figures, pLaTeX2e, uses amsmath, amssymb, amsthm,
graphic