Eric Hynan:" ...In 1986 I gave a paper, “The Affinity between Nabokov’s Short Stories and Chess Problems,” at the Vladimir Nabokov Society Meeting, Modern Language Association Convention, New York (abstract published in The Nabokovian, 18 [1987]). Therein I argued that novels (or memoirs) and chess problems are very different: chess games, novels and memoirs are developing, sequential narratives, whereas short stories and chess problems depend on single key moves that determine everything else, that the author sets for the reader/solver to figure out. Pale Fire thus would be sort of a hybrid: it has two more or less sequential narratives, Shade’s poem and Kinbote’s Zemblan fantasy; and is also akin to a chess problem, where the key move is that reader needs to figure out that Kinbote is mad (and/or might be Botkin)."

You cited only two options: Shade's poem and Kinbote's Zemblan fantasy. Aren't you forgetting the fact that mad Kinbote has also created a New Wye fantasy that includes Shade's life at home and in Wordsmith?

John Shade's autobiography, extracted from his poem, is rather succint. Hazel's poltergeist and barn episode, the daily process of composing Pale Fire with pauses for a dip of brandy, birthday party guests and accidents in the snow, even John Shade's heart attack as announced in the NYT are examples of Kinbote's fantasy.

btw:Whenever I write anything about Pale Fire I must double-check it later, because my memory is always leading me astray. Right now I may have introduced one or more misattributions to CK that are also found in JS's poem. Corrections are welcome.