  Recent developments in superstring theory and noncommutative geometry are
deeply related to the idea of Eguchi-Kawai reduction in large N gauge theories
which dates back to early 80s. After a general review on this subject including
revived interests in solving planar QCD, we present some results in the
superstring matrix model suggesting the dynamical generation of 4d space-time
due to the collapse of the eigenvalue distribution. We then discuss interesting
dynamical properties of field theories in noncommutative geometry, which have
been revealed by Monte Carlo simulations of twisted reduced models. We conclude
with a comment on the recent proposal for a lattice construction of
supersymmetric gauge theories based on reduced models.
