<t>ah, indeed! an elegant argument.QuoteOriginally posted by: wileyswwill0t5, i was thinking of reductio ad absurdum by assuming E[n] < infty, then by Wald's equation, E[S_n]=E[X]*E[n]=0, however, y<=S_n<y+1 by the stopping criteria, thus contradiction when y>0.(actually looking at your argument, si...