=+

(a) Suppose that d1, d2 ,... are positive and Ex- , di -, that s, 2 522 "≥

0 and lim , Sx = 0, and that DR_ s&dx = 1. Let & be the convex polygon whose successive sides have slopes -s1, - s2, ... and lengths d1, d2 ,... when pro-

jected on the horizontal axis: « has value 1 - Ef _, s,d, at t, =

d, + . . . +di. If s„ =0, there are in effect only n sides. Let (t) =(1-[2])h- 1,1)(t) be the characteristic function in the last line in the table on p. 348, and show that (!)

is a convex combination of the characteristic functions g(t/t) and hence is itself a characteristic function.