I just ran the following code in t2.8, (define (tak x y z) (lables (((tak1 x y z) (if (not (< y x) z (block (tak1 (tak1 (fx- x 1) y z) (tak1 (fx- y 1) z x) (tak1 (fx- z 1) x y))))))) (tak1 x y z))) and got the following results for (tak 18 12 6) Dn300 16.5 seconds Dn460 8.8 seconds Can anyone explain why these results are so much worse that the ones published on AI-List. -Charlie Dolan