Lemma 2 Let R be an integral domain and a a non–zero element of R. If the polynomial f ∈ R[x1, . . . , xn] is non–zero and divisible by x1 + · · · + xn − a, it contains more than n monomials.
Lemma 2 Let R be an integral domain and a a non–zero element of R. If thepolynomial f ∈ R[x1, . . . , xn] is non–zero and divisible by x1 + · · · + xn − a, itcontains more than n monomials.