User blog comment:B1mb0w/Alpha Function Program Code/@comment-25337554-20150803100710/@comment-10262436-20150803102702

The more zeros you get, the more nested functions but the whole process does terminate. Remember that if the 2nd parameter has to expand into nested D functions, because the 1st parameter is zero, then, all the nested D functions will have one less parameter. So eventually you will just get D(0) nested functions which terminate trivially. I will have a look at this number and see what else I can suggest. Cheers