lt 0 s x true lt x 0 false lt s x s y lt x y fibo 0 fib 0 fibo s 0 fib s 0 fibo s s x sum fibo s x fibo x fib 0 s 0 fib s 0 s 0 fib s s x if true 0 s s x 0 0 if true c s s x a b if lt s c s s x s c s s x b c if false c s s x a b sum fibo a fibo b sum x 0 x sum x s y s sum x y 2.2 fibo s s x fibo s x if false c s s x a b sum fibo a fibo b fibo 0 fib 0 if true c s s x a b if lt s c s s x s c s s x b c fibo s 0 fib s 0 lt s x s y lt x y if false c s s x a b fibo a if true c s s x a b lt s c s s x fib s s x if true 0 s s x 0 0 fibo s s x fibo x fibo s s x sum fibo s x fibo x if false c s s x a b fibo b sum x s y sum x y true fib s s x if true 0 s s x 0 0 false if true c s s x a b if lt s c s s x s c s s x b c true Failed! NaTT certifiable-1.6