% non-uniqueness of left-inverses

let X = {1,2,3,4}

find [op:X*X -> X] {
    all x,y,z op(op(x,y), z) = op(x, op(y,z))
    AND
    all x (op(x,1) = op(1,x) & op(x,1) = x)
    AND
    find [li1,li2,r:X] {
        li1 != li2 
        AND
        op(li1,r) = 1
        AND
        op(li2,r) = 1
    }
}
