fact: Definition mkPX P i Q := match P with | Pc c => if c ?=! cO then mkPinj xH Q else PX P i Q | Pinj _ _ => PX P i Q | PX P' i' Q' => if Q' ?== P0 then PX P' (i' + i) Q else PX P i Q end.
imports: Setoid Morphisms BinList BinPos BinNat BinInt Ring_theory