(refl): x1
x1 * 2
x1 * 3
x1 * 4
x1 * 4
x1 * 5
x1 * (1 + -1)
x1 * (1 + (1 + -1))
x1 * (1 + (1 + -2))
x1 * (1 + (1 + (-1 + -1)))
x1 * 5
x2 * (1 + -1) + x1 * (1 + -1)
x2 * (1 + (1 + -2)) + x1 * (1 + (1 + (1 + -3)))
x1 * 2 + x2 * (1 + -1)
x2 * 2 + (x1 * 3 + x2 * x1 * (1 + (1 + -32)))
x1 + (-0 + x3 * x2 * (3 + -2))
x1 * 2 + (x3 * x2 * 3 + (x3 * x1 * (1 + -3) + x2 * x1 * (1 + (1 + -2))))
x1 * 2 + x2 * (1 + -1)