Negatives in questions (and answers): the case of ουκουν (…) ου. Or: does Ancient Greek have a word for ‘no’?

Among the uses of ουκουν Denniston (19542: 435) mentions: "ουκουν ου, ουκουν …
ου, expecting a negative answer." In this paper it is argued that Denniston’s view,
which is shared by most (all?) other grammars and dictionaries (e.g. Kuhner & Gerth
1898-19043: 2, 164: "Wenn nach ουκουν eine verneinende Antwort erwartet wird, so
wird demselben die Negation ου nachgesetzt", Smyth 1956: §2651a: "ουκουν ου expects
the answer no", LSJ 1940: s.v. ουκουν) should be rejected. Actually, the answer is never
no. As always, ουκουν expects an affirmative answer, in this case to a negated question:
‘Is it not the case, then, that not X?’ = ‘Surely, then, not X?’. To be sure, ου does occur
as an answer, but this can be shown to be a proposition (or sentence) negative (= not),
rather than an answering particle like no. This is compared with negatives in several
other languages, notably Latin and Old French. Finally, Modern Greek is briefly discussed,
which, unlike Ancient Greek, does have a negative answering particle, viz. όχι,
alongside a proposition negative, viz. δε(ν).