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Some estimations of positive and negative eigenvalues. (English) Zbl 0942.35123

The author gives some simple estimates of positive and negative eigenvalues for the inhomogeneous membrane boundary problem \[ -\Delta u=\lambda mu ,\qquad u|_{\partial D} =0 \] where \(D\subset \mathbb{R}^2\) is a simple connected domain and \(m\) is a real bounded function on \(D\).

MSC:

35P15 Estimates of eigenvalues in context of PDEs
35J25 Boundary value problems for second-order elliptic equations