Constructing infinitely many smooth structures on small 4-manifolds

The purpose of this article is two-fold. First we outline a general construction scheme for producing simply connected minimal symplectic -manifolds with small Euler characteristics. Using this scheme, we illustrate how to obtain irreducible symplectic -manifolds homeomorphic but not diffeomorphic to (Formula presented.) for k = 1, …, 4, or to (Formula presented.) for l = 1, …, 6. Secondly, for each of these homeomorphism types, we show how to produce an infinite family of pairwise nondiffeomorphic nonsymplectic 4-manifolds belonging to it. In particular, we prove that there are infinitely many exotic irreducible nonsymplectic smooth structures on, (Formula presented.) and (Formula presented.).