<p>In this paper, the authors consider meromorphic solutions of nonhomogeneous differential equation <Equation ID="Equ1"> <EquationSource Format="TEX">\(f^{n}(f^{\prime}+af)+P_{d}(z,f)=u(z){\rm{e}}^{v(z)},\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <msup> <mi>f</mi> <mrow> <mi>n</mi> </mrow> </msup> <mo stretchy="false">(</mo> <msup> <mi>f</mi> <mrow> <mi mathvariant="normal">′</mi> </mrow> </msup> <mo>+</mo> <mi>a</mi> <mi>f</mi> <mo stretchy="false">)</mo> <mo>+</mo> <msub> <mi>P</mi> <mrow> <mi>d</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mi>z</mi> <mo>,</mo> <mi>f</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mi>u</mi> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> <msup> <mrow> <mrow> <mi mathvariant="normal">e</mi> </mrow> </mrow> <mrow> <mi>v</mi> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> </mrow> </msup> <mo>,</mo> </math></EquationSource> </Equation> where <i>n</i> is a positive integer, <i>a</i> is a nonzero constant, <i>P</i><sub><i>d</i></sub>(<i>z, f</i>) is a differential polynomial in <i>f</i>(<i>z</i>) of degree <i>d</i> with rational functions as its coefficients and <i>d</i> ≤ <i>n</i> − 1, <i>u</i>(<i>z</i>) is a nonzero rational function, <i>v</i>(<i>z</i>) is a nonconstant polynomial with <i>v</i>′(<i>z</i>) ≠ (<i>n</i> + 1)<i>a, v</i>′(<i>z</i>) ≠ −<i>na</i> and <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(v^{\prime}(z)\ne-{(n+1)^{2}\over{n}}a\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <msup> <mi>v</mi> <mrow> <mi mathvariant="normal">′</mi> </mrow> </msup> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> <mo>≠</mo> <mo>−</mo> <mrow> <mfrac> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo>+</mo> <mn>1</mn> <msup> <mo stretchy="false">)</mo> <mrow> <mn>2</mn> </mrow> </msup> </mrow> <mrow> <mi>n</mi> </mrow> </mfrac> </mrow> <mi>a</mi> </math></EquationSource> </InlineEquation>. They prove that if it admits a meromorphic solution <i>f</i>(<i>z</i>) with finitely many poles, then <Equation ID="Equ2"> <EquationSource Format="TEX">\(\matrix{{f(z) = s(z){{\rm{e}}^{{{v(z)} \over {n + 1}}}}} &amp; {{\text{and}}} &amp; {{P_d}(z,f) \equiv 0,}}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mtable> <mtr> <mtd> <mrow> <mi>f</mi> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mi>s</mi> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> <mrow> <msup> <mrow> <mrow> <mi mathvariant="normal">e</mi> </mrow> </mrow> <mrow> <mrow> <mfrac> <mrow> <mi>v</mi> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>n</mi> <mo>+</mo> <mn>1</mn> </mrow> </mfrac> </mrow> </mrow> </msup> </mrow> </mrow> </mtd> <mtd> <mrow> <mrow> <mtext>and</mtext> </mrow> </mrow> </mtd> <mtd> <mrow> <mrow> <msub> <mi>P</mi> <mi>d</mi> </msub> </mrow> <mo stretchy="false">(</mo> <mi>z</mi> <mo>,</mo> <mi>f</mi> <mo stretchy="false">)</mo> <mo>≡</mo> <mn>0</mn> <mo>,</mo> </mrow> </mtd> </mtr> </mtable> </math></EquationSource> </Equation> where <i>s</i>(<i>z</i>) is a rational function and <i>s</i><sup><i>n</i></sup>[(<i>n</i> + 1)<i>s</i>′ + <i>sv</i>′] + (<i>n</i> + 1)<i>as</i><sup><i>n</i>+1</sup> = (<i>n</i> + 1)<i>u</i>. Using this result, they also prove that if <i>f</i>(<i>z</i>) is a transcendental entire function, then <i>f</i><sup><i>n</i></sup>(<i>f</i>′ + <i>af</i>) + <i>q</i><sub><i>m</i></sub>(<i>f</i>) assumes every complex number <i>α</i> infinitely many times, except for a possible value <i>q</i><sub><i>m</i></sub>(0), where <i>n, m</i> are positive integers with <i>n</i> ≥ <i>m</i> + 1 and <i>q</i><sub><i>m</i></sub>(<i>f</i>) is a polynomial in <i>f</i>(<i>z</i>) with degree <i>m</i>.</p>

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On Meromorphic Solutions of Non-linear Differential Equations and Their Applications

  • Linke Ma,
  • Liangwen Liao

摘要

In this paper, the authors consider meromorphic solutions of nonhomogeneous differential equation \(f^{n}(f^{\prime}+af)+P_{d}(z,f)=u(z){\rm{e}}^{v(z)},\) f n ( f + a f ) + P d ( z , f ) = u ( z ) e v ( z ) , where n is a positive integer, a is a nonzero constant, Pd(z, f) is a differential polynomial in f(z) of degree d with rational functions as its coefficients and dn − 1, u(z) is a nonzero rational function, v(z) is a nonconstant polynomial with v′(z) ≠ (n + 1)a, v′(z) ≠ −na and \(v^{\prime}(z)\ne-{(n+1)^{2}\over{n}}a\) v ( z ) ( n + 1 ) 2 n a . They prove that if it admits a meromorphic solution f(z) with finitely many poles, then \(\matrix{{f(z) = s(z){{\rm{e}}^{{{v(z)} \over {n + 1}}}}} & {{\text{and}}} & {{P_d}(z,f) \equiv 0,}}\) f ( z ) = s ( z ) e v ( z ) n + 1 and P d ( z , f ) 0 , where s(z) is a rational function and sn[(n + 1)s′ + sv′] + (n + 1)asn+1 = (n + 1)u. Using this result, they also prove that if f(z) is a transcendental entire function, then fn(f′ + af) + qm(f) assumes every complex number α infinitely many times, except for a possible value qm(0), where n, m are positive integers with nm + 1 and qm(f) is a polynomial in f(z) with degree m.