Regularity for Solutions of Second-Order Nonlinear Integrodifferential Functional Equations.

We deal with the well-posedness for solutions of nonlinear integrodifferential equations of secondorder in Hilbert spaces by converting the problem into the contraction mapping principle with more general conditions on the principal operators and the nonlinear terms and obtain a variation of constant formula of solutions of the given nonlinear equations. [ABSTRACT FROM AUTHOR]