A Liapunov Functional for a Linear Integral Equation

(2) C(t, s) ≥ 0, Cs(t, s) ≥ 0, Cst(t, s) ≤ 0, Ct(t, s) ≤ 0. The subscripts denote the usual partial derivatives and a is continuous. Convex kernels for both integral and integrodifferential equations are commonly used in the study of many real-world problems. Discussions may be found in Volterra [13], Grippenberg-Londen-Staffans [7; see index], Londen [10], and throughout Burton [4], for example. In 1963 Levin [8] followed a suggestion of Volterra and constructed a Liapunov functional for