Ποιανού (=whose) 1) refers to a masculine owner (Ποιανού είναι το βιβλίο; -Του Γιάννη) 2) used when you don't know the owner's gender (Ποιανού είναι το σπίτι; -Της μητέρας μου. -Του πατέρα μου.)
Ποιανής (=whose) refers to a feminine owner, when all possible owners are feminine (Κορίτσια, ποιανής είναι αυτό το σουτιέν; -Της Χρύσας)
"Ποιανούς" is wrong.
ποιανούς ή ποιους is the masculine accusative plural of ποιος
Με ποιανούς ανθρόπους δουλεύεις/ with what people do you work
Η ερωτηματική αντωνυμία ποιος/ The interrogative pronoun who https://el.m.wiktionary.org/wiki/%CF%80%CE%BF%CE%B9%CE%BF%CF%82
"Ποιανούς" must be dialectal. I've never heard such type in Athens and Thessaloniki.
Neither have I, nor ποιανού. I have always used ποιου for whose and ποιους for the accusative plural but wiktionary has the alternatives ποιανού and ποιανούς without comments
I also think that ποιανούς might be dialectal. I've heard ποιανού many times; but I think more common (or at least I use it more) is τίνος. Ποιου might be used also.
I understand αυτή here refers to "this" feminine noun, but can this sentence also mean "Whose bear is she?" or is there another way to ask that (where "she" refers to a female bear)?
Αυτός/αυτή/αυτό are used as both personal and demonstrative pronouns. Here it's the latter. Since in greek pronouns give away the gender, I guess the distinction between "Whose bear is this?" and "Whose bear is she?" doesn't make much sense to me.
A toybear is usually diminutive in Greek
αρκουδάκι = small bear, baby bear, teddy bear
Winnie the Pooh = Γουίνι το Αρκουδάκι
So, instead of having a separate word like "whose", the genitive like "of whom" is always used in Greek?
What do you think "whose" is, if not the genitive of "who"? :)
(Or at least it used to be, back when English still had a separate genitive case -- this form survived so now we have "whose" and "who".)
Well, in Russian we have separate words чей (whose), which is used only in questions about possession, and кого, which is strictly genitive (and accusative). And it sounds awkward when кого is used to ask about possession, yet understandable.
Ποιανούς is used, but ive only ever heard it with greek Americans so its probably just colloquial. My γιαγιά says it. Π.χ. ποιανούς είναι αυτά τα παπούτσια στην σαλόνι;;;
ποιούς/ ποιανούς is accusative plural of the masc. ποιος https://el.m.wiktionary.org/wiki/%CF%80%CE%BF%CE%B9%CE%BF%CF%82