On uniqueness polynomials for meromorphic functions

Abstract

AbstractA polynomial P(w) is called a uniqueness polynomial (or a uiqueness polynomial in a broad sense) if P(f) = cP(g) (or P(f) = P(g)) implies f = g for any nonzero constant c and nonconstant meromorphic functions f and g on C. We consider a monic polynomial P(w) without multiple zero whose derivative has mutually distinct k zeros ej with multiplicities qj. Under the assumption that P(el) ≠ P(em) for all distinct l and m, we prove that P(w) is a uniqueness polynomial in a broad sense if and only if ∑l<mqlqm > ∑l ql. We also give some sufficient conditions for uniqueness polynomials.