Let p, q, r, s be polynomials with integer coefficients. This paper presents a fast method, using very little temporary storage, to find all small integers (a, b, c, d) satisfying p(a)+q(b) = r(c)+s(d). Numerical results include all small solutions to a4 + b4 +c4 = d4; all small solutions to a4 + b4 = c4 +d4; and the smallest positive integer that can be written in 5 ways as a sum of two coprim...