To my teachers, BertBundesen and Peter Lettice This paper is concerned with the space of multipliers
from Lp(G) to Lq(G) for various pairs of indices p and q, where G is an LCA group.
We show that if 1 ≦ p < 2 < q ≦∞, and G is noncompact, then there are
multipliers of type (p,q) whose ‘Fourier transforms’ are not measures. This is an
extension of a result of Hörmander, and completes work begun in two earlier
papers (this journal, 1966). In the second part, we show that if G is infinite,
many of the natural inclusion relations between spaces of multipliers are
proper.