even 0 true even s 0 false even s s x even x half 0 0 half s s x s half x plus 0 y y plus s x y s plus x y times 0 y 0 times s x y if_times even s x s x y if_times true s x y plus times half s x y times half s x y if_times false s x y plus y times x y even 1 0 0 true 0 s 1 false 0 half 1 plus 2 times 2 if_times 3 INNERMOST ./TRS/AG01/#4.29.trs