Section ImfsetTh.
Variables (key : unit) (K V : choiceType).
Implicit Types (f : K -> V) (g : V -> K) (A V : {fset K}).

Lemma eq_imfset (f f' : K -> V) (p q : finmempred _):
f =1 f' -> (forall x, in_mem x p = in_mem x q) ->
imfset key f p = imfset key f' q.