lt s X s Y lt X Y lt 0 s U true lt V 0 false eq W W true eq s P 0 false eq 0 s X1 false member Y1 null false member U1 fork V1 W1 P1 if lt U1 W1 member U1 V1 if eq U1 W1 true member U1 P1 X a Y a U a V a W a P a X1 a Y1 a U1 a V1 b W1 a P1 b 0 a eq a a c false c fork b a b b if c c c c lt a a c member a b c null b s a a true c FULL benchmarks/applicative/Applicative_05__BTreeMember.atrs