“…An important observation by Diesselhorst [5] that the function 1 2 fu ds 1"2*+LW) ° '5) satisfies the equation V(it(«)V^) = 0 inQ, (1.6) plays a crucial role in the papers [3], [4], In the special case td = r, u r2, <p = <p,, u = on r(, u = u on rD, -+ yu = g0 on dQ\ro .…”