(format LCTRS :logic QF_LIA)
(fun return 1 :sort (Int Int))
(fun sum2 2 :sort (Int Int Int))
(fun u 4 :sort (Int Int Int Int Int))

(rule (sum2 m n) (u m n m 0) :vars ((m Int) (n Int)))
(rule (u m n i total) (u m n (+ i 1) (+ total i)) :guard (<= i n) :vars ((m Int) (n Int) (i Int) (total Int)))
(rule (u m n i total) (return total) :guard (not (<= i n)) :vars ((m Int) (n Int) (i Int) (total Int)))