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On definitions of superharmonic functions

Seizô Itô (1975)

Annales de l'institut Fourier

Let A be an elliptic differential operator of second order with variable coefficients. In this paper it is proved that any A -superharmonic function in the Riesz-Brelot sense is locally summable and satisfies the A -superharmonicity in the sense of Schwartz distribution.

On Dirichlet-Schrödinger operators with strong potentials

Gabriele Grillo (1995)

Studia Mathematica

We consider Schrödinger operators H = -Δ/2 + V (V≥0 and locally bounded) with Dirichlet boundary conditions, on any open and connected subdomain D n which either is bounded or satisfies the condition d ( x , D c ) 0 as |x| → ∞. We prove exponential decay at the boundary of all the eigenfunctions of H whenever V diverges sufficiently fast at the boundary ∂D, in the sense that d ( x , D C ) 2 V ( x ) as d ( x , D C ) 0 . We also prove bounds from above and below for Tr(exp[-tH]), and in particular we give criterions for the finiteness of such trace....

On discontinuous Galerkin method and semiregular family of triangulations

Aleš Prachař (2006)

Applications of Mathematics

Discretization of second order elliptic partial differential equations by discontinuous Galerkin method often results in numerical schemes with penalties. In this paper we analyze these penalized schemes in the context of quite general triangular meshes satisfying only a semiregularity assumption. A new (modified) penalty term is presented and theoretical properties are proven together with illustrative numerical results.

On Dittmar's approach to the Beltrami equation

Ewa Ligocka (2002)

Colloquium Mathematicae

We recall an old result of B. Dittmar. This result permits us to obtain an existence theorem for the Beltrami equation and some other results as a direct consequence of Moser's classical estimates for elliptic operators.

On elliptic systems pertaining to the Schrödinger equation

J. Chabrowski, E. Tonkes (2003)

Annales Polonici Mathematici

We discuss the existence of solutions for a system of elliptic equations involving a coupling nonlinearity containing a critical and subcritical Sobolev exponent. We establish the existence of ground state solutions. The concentration of solutions is also established as a parameter λ becomes large.

On exact results in the finite element method

Ivan Hlaváček, Michal Křížek (2001)

Applications of Mathematics

We prove that the finite element method for one-dimensional problems yields no discretization error at nodal points provided the shape functions are appropriately chosen. Then we consider a biharmonic problem with mixed boundary conditions and the weak solution u . We show that the Galerkin approximation of u based on the so-called biharmonic finite elements is independent of the values of u in the interior of any subelement.

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