Introduction.In the present paper, we shall characterize some functions, those which satisfy a Lipschitz condition, as Fourier transforms of a certain sub-class of L p (R k ), and we shall give a contraction theorem of L p -Fourier transforms.A complex valued function f(x ly x 2 , , x k ) on R k , the k-άim. Euclidean space, is denoted by f(x).When / has the following property (i) or (ii), we say / is (p)normalized:
for any finiteJi+y interval I, where 1/p + 1/p' = 1; (ii) if p = 1, then / is continuous and lim^,.^ f(x) = 0. We denote the j-th difference of /(a?), with respect to heR k , by Δl(f(x)), that is, Δί(f(x)) -Σ(-l) i+m ( 3 )f(x + mh) . m=0 \m)