let ( |><| ) p_1 p_2 =
let r1 = rate p_1 in
let r2 = rate p_2 in
let qred (num, den) =
let g = gcd num den in
let num = num / g in
let den = den / g in
let sign = den / abs den in
(sign * num, abs den)
in
qred r1 = qred r2