... AND BAS¸AK Z. G¨URELedges are parallel to the coordinate axes. The product [a, b] × I2mis alwaysassumed to be embedded intoR2m+1(henceforth, the standard embedding)so that the interval ... points (a, x), the “entrance”, and (b, y), the “exit”, are on the same characteristic, thenx = y.Inother words, for a characteristic that meets both the bottomand the top of the plug, its top ... continuity in (x, y)att =0. Fort =0 ,the integral (5.5)can be broken up into two parts: the integral over [0,δ] and the integral over[δ, t]. By (5.6), the first part can be made arbitrarily small...