The search session has expired. Please query the service again.

The search session has expired. Please query the service again.

The search session has expired. Please query the service again.

Displaying 61 – 80 of 209

Showing per page

On Kelvin type transformation for Weinstein operator

Martina Šimůnková (2001)

Commentationes Mathematicae Universitatis Carolinae

The note develops results from [5] where an invariance under the Möbius transform mapping the upper halfplane onto itself of the Weinstein operator W k : = Δ + k x n x n on n is proved. In this note there is shown that in the cases k 0 , k 2 no other transforms of this kind exist and for case k = 2 , all such transforms are described.

On log-subharmonicity of singular values of matrices

Bernard Aupetit (1997)

Studia Mathematica

Let F be an analytic function from an open subset Ω of the complex plane into the algebra of n×n matrices. Denoting by s 1 , . . . , s n the decreasing sequence of singular values of a matrix, we prove that the functions l o g s 1 ( F ( λ ) ) + . . . + l o g s k ( F ( λ ) ) and l o g + s 1 ( F ( λ ) ) + . . . + l o g + s k ( F ( λ ) ) are subharmonic on Ω for 1 ≤ k ≤ n.

On mean value properties involving a logarithm-type weight

Nikolai G. Kuznecov (2024)

Mathematica Bohemica

Two new assertions characterizing analytically disks in the Euclidean plane 2 are proved. Weighted mean value property of positive solutions to the Helmholtz and modified Helmholtz equations are used for this purpose; the weight has a logarithmic singularity. The obtained results are compared with those without weight that were found earlier.

Currently displaying 61 – 80 of 209