le s x 0 false le 0 y true le s x s y le x y double 0 0 double s x s s double x log 0 logError log s x loop s x s 0 0 loop x s y z if le x s y x s y z if true x y z z if false x y z loop x double y s z maplog xs mapIter xs nil mapIter xs ys ifmap isempty xs xs ys ifmap true xs ys ys ifmap false xs ys mapIter droplast xs cons log last xs ys isempty nil true isempty cons x xs false last nil error last cons x nil x last cons x cons y xs last cons y xs droplast nil nil droplast cons x nil nil droplast cons x cons y xs cons x droplast cons y xs a b a c le 2 s 1 0 0 false 0 true 0 double 1 log 1 logError 0 loop 3 if 4 maplog 1 mapIter 2 nil 0 ifmap 3 isempty 1 droplast 1 cons 2 last 1 error 0 a 0 b 0 c 0 FULL ./TRS/secret07/aprove/aprove06.trs