<p>Motivated by lower bound estimates of Payne and Escobar for the classical Steklov problem, we study sharp lower bounds for the first eigenvalue of Steklov-type problems on compact surfaces with smooth boundary. We prove that, if the Gaussian curvature satisfies <InlineEquation ID="IEq1"><EquationSource Format="MATHML"><math><mi>K</mi><mo>≥</mo><mo>−</mo><mi>α</mi></math></EquationSource><EquationSource Format="TEX">$K \ge -\alpha $</EquationSource></InlineEquation> and the geodesic curvature of the boundary satisfies <InlineEquation ID="IEq2"><EquationSource Format="MATHML"><math><msub><mi>k</mi><mi>g</mi></msub><mo>≥</mo><mi>c</mi><mo>&gt;</mo><mn>0</mn></math></EquationSource><EquationSource Format="TEX">$k_{g} \ge c &gt; 0$</EquationSource></InlineEquation>, then the first eigenvalue of the Steklov-type eigenvalue problem satisfies an optimal inequality and equality holds only for the Euclidean disk. In particular, we obtain a sharp lower bound for the first eigenvalue of a Schrödinger-Steklov eigenvalue problem. If the Gaussian curvature satisfies <InlineEquation ID="IEq3"><EquationSource Format="MATHML"><math><mi>K</mi><mo>≥</mo><mo>−</mo><mi>α</mi></math></EquationSource><EquationSource Format="TEX">$K \ge -\alpha $</EquationSource></InlineEquation> and the geodesic curvature satisfies <InlineEquation ID="IEq4"><EquationSource Format="MATHML"><math><msub><mi>k</mi><mi>g</mi></msub><mo>≥</mo><mi>c</mi><mo>&gt;</mo><mn>0</mn></math></EquationSource><EquationSource Format="TEX">$k_{g} \ge c &gt; 0$</EquationSource></InlineEquation>, then the first eigenvalue <InlineEquation ID="IEq5"><EquationSource Format="MATHML"><math><msub><mi>σ</mi><mn>1</mn></msub></math></EquationSource><EquationSource Format="TEX">$\sigma _{1}$</EquationSource></InlineEquation> satisfies <Equation ID="Equa"><EquationSource Format="MATHML"><math><msub><mi>σ</mi><mn>1</mn></msub><mo>+</mo><mfrac><mi>α</mi><msub><mi>σ</mi><mn>1</mn></msub></mfrac><mo>≥</mo><mi>c</mi><mo>,</mo></math></EquationSource><EquationSource Format="TEX">\( \sigma _{1} + \frac{\alpha}{\sigma _{1}} \ge c, \)</EquationSource></Equation> where equality holds if and only if the surface is a Euclidean disk of radius <InlineEquation ID="IEq6"><EquationSource Format="MATHML"><math><mn>1</mn><mo stretchy="false">/</mo><mi>c</mi></math></EquationSource><EquationSource Format="TEX">$1/c$</EquationSource></InlineEquation> and <InlineEquation ID="IEq7"><EquationSource Format="MATHML"><math><mi>α</mi><mo>=</mo><mn>0</mn></math></EquationSource><EquationSource Format="TEX">$\alpha = 0$</EquationSource></InlineEquation>. We also prove that the first eigenvalue of a fourth-order Steklov-type problem is bounded below by 2<i>c</i> under nonnegative Gaussian curvature, with equality again characterizing the Euclidean disk.</p>

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Sharp lower bounds for the first eigenvalue of Steklov-type eigenvalue problems on a compact surface

  • Gunhee Cho,
  • Keomkyo Seo

摘要

Motivated by lower bound estimates of Payne and Escobar for the classical Steklov problem, we study sharp lower bounds for the first eigenvalue of Steklov-type problems on compact surfaces with smooth boundary. We prove that, if the Gaussian curvature satisfies Kα$K \ge -\alpha $ and the geodesic curvature of the boundary satisfies kgc>0$k_{g} \ge c > 0$, then the first eigenvalue of the Steklov-type eigenvalue problem satisfies an optimal inequality and equality holds only for the Euclidean disk. In particular, we obtain a sharp lower bound for the first eigenvalue of a Schrödinger-Steklov eigenvalue problem. If the Gaussian curvature satisfies Kα$K \ge -\alpha $ and the geodesic curvature satisfies kgc>0$k_{g} \ge c > 0$, then the first eigenvalue σ1$\sigma _{1}$ satisfies σ1+ασ1c,\( \sigma _{1} + \frac{\alpha}{\sigma _{1}} \ge c, \) where equality holds if and only if the surface is a Euclidean disk of radius 1/c$1/c$ and α=0$\alpha = 0$. We also prove that the first eigenvalue of a fourth-order Steklov-type problem is bounded below by 2c under nonnegative Gaussian curvature, with equality again characterizing the Euclidean disk.