(SETQ GRAPHFNS @(LOSE TER SUCCESSORS))

(DE LOSE (P) (MEMBER (CAR P) (CDR P)))

(DE TER (P) (EQ (CAR P) FINAL))

(DE SUCCESSORS (P) (MAPCAR (FUNCTION (LAMBDA (X) (CONS X P)))
(CDR (ASSOC (CAR P) GRAPH))))

(SETQ FINAL @F)

(SETQ GRAPH @((A B) (B A C D) (C B D E) (D B C E) (E C D F) (F E)))