Problem: all (\x. P) -> P all (\x. and (P' x) (Q' x)) -> and (all P') (all Q') all (\x. or (P' x) Q) -> or (all P') Q all (\x. or P (Q' x)) -> or P (all Q') Proof: Higher-Order Church Rosser Processor: all (\x. P) -> P all (\x. and (P' x) (Q' x)) -> and (all P') (all Q') all (\x. or (P' x) Q) -> or (all P') Q all (\x. or P (Q' x)) -> or P (all Q') critical peaks: 8 and 8 9 <-[]-> and (all (\x. 8)) (all (\x. 9)) or 13 14 <-[]-> or (all (\x. 13)) 14 or 18 19 <-[]-> or 18 (all (\x. 19)) and (all (\x. 24)) (all (\x. 25)) <-[]-> and 24 25 or (all (\x. 44)) 45 <-[]-> or 44 45 or (all (\x. 59)) 60 <-[]-> or 59 (all (\x. 60)) or 66 (all (\x. 67)) <-[]-> or 66 67 or 78 (all (\x. 79)) <-[]-> or (all (\x. 78)) 79 Higher-Order Closedness Processor: all critical pairs are (almost) development closed Qed