We investigate the variational inequality with pseudomonotone operator
s (in the sense of Karamardian) in Banach spaces. New existence result
s which extend many known results in infinite-dimensional spaces are d
erived under rather weak assumptions. New uniqueness results which als
o seem to be new even in finite-dimensional spaces are also derived. I
n particular, new existence and uniqueness results for the complementa
rity problem with pseudomonotone operators in Banach spaces are obtain
ed. Also, existence and uniqueness results for minimization problems w
ith pseudoconvex functions in Banach spaces are obtained.