Let k(x,t) be a C1 kernel of a
positive integral operator on L2(E) where E is compact. It is shown that
certain singular self-adjoint operators A on L2(E), consisting of the sum
of a multiplication operator and a generalized Hilbert transform integral
operator with Kernel ik(x,t)(x − t)−1, are analogous to—sometimes even to the
extent of unitary equivalence—operators, about which a good deal more
is known, of the same structure as A but with k(x,t) of the special form
ϕ(x)ϕ(t).