DIFFERENTIAL EQUATIONS RELATED TO FAMILY A

Abstract

Let h be a meromorphic function with few poles and zeros. By Nevanlinna's value distribution theory we prove some new properties on the polynomials in h with the coefficients being small functions of h. We prove that if f is a meromorphic function and if <TEX>$f^m$</TEX> is identically a polynomial in h with the constant term not vanish identically, then f is a polynomial in h. As an application, we are able to find the entire solutions of the differential equation of the type <TEX>$$f^n+P(f)=be^{sz}+Q(e^z)$$</TEX>, where P(f) is a differential polynomial in f of degree at most n-1, and Q(<TEX>$e^z$</TEX>) is a polynomial in <TEX>$e^z$</TEX> of degree k <TEX>$\leqslant$</TEX> max {n-1, s(n-1)/n} with small functions of <TEX>$e^z$</TEX> as its coefficients.