YES ignored inputs: (COMMENT rules to obtain NNF of first-order formulas without DNE ) NRS: [ (0): |- (not (exists [a][]Q)) -> (forall [a](not []Q)), (1): |- (not (forall [a][]Q)) -> (exists [a](not []Q)), (2): |- (not (and <[]P,[]Q>)) -> (or <(not []P),(not []Q)>), (3): |- (not (or <[]P,[]Q>)) -> (and <(not []P),(not []Q)>) ] Check confluence by parallel closed criterion left-linear uniform BCPs: (0 on 0(out)): { |- < (forall [a](not []Q_1)) <= (not (exists [a][]Q_1)) => (forall [a](not []Q_1)) >, a#Q_1 |- < (forall [a](not [(a b)]Q_1)) <= (not (exists [b][]Q_1)) => (forall [b](not []Q_1)) > } (1 on 1(out)): { |- < (exists [a](not []Q_1)) <= (not (forall [a][]Q_1)) => (exists [a](not []Q_1)) >, a#Q_1 |- < (exists [a](not [(a b)]Q_1)) <= (not (forall [b][]Q_1)) => (exists [b](not []Q_1)) > } (2 on 2(out)): { |- < (or <(not []P_1),(not []Q_1)>) <= (not (and <[]P_1,[]Q_1>)) => (or <(not []P_1),(not []Q_1)>) > } (3 on 3(out)): { |- < (and <(not []P_1),(not []Q_1)>) <= (not (or <[]P_1,[]Q_1>)) => (and <(not []P_1),(not []Q_1)>) > } all BCPs are parallel closed result: YES time: 4 msec.