“…In fact, the computation of the probability that a standard Brownian motion remains between two given boundaries is a complex question that has occupied many researchers over many years (see, e.g., Anderson, 1960;Robbins and Siegmund, 1970;Durbin, 1971;Lerche, 1986;Durbin, 1992;Daniels, 1996;Borodin and Salminen, 2002;Li, 2003). In this literature, explicit representations of two-sided boundary crossing probabilities are extremely rare and mostly address linear cases (Anderson, 1960;Hall, 1997), though explicit computations are available for a few nonlinear boundaries (Robbins and Siegmund, 1970;Daniels, 1996;Novikov et al, 1999).…”