Displaying similar documents to “On the matrices of central linear mappings”

On ( j , k ) -symmetrical functions

Piotr Liczberski, Jerzy Połubiński (1995)

Mathematica Bohemica

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n the present paper the authors study some families of functions from a complex linear space X into a complex linear space Y . They introduce the notion of ( j , k ) -symmetrical function ( k = 2 , 3 , ⋯ ; j = 0 , 1 , ⋯ , k - 1 ) which is a generalization of the notions of even, odd and k -symmetrical functions. They generalize the well know result that each function defined on a symmetrical subset U of X can be uniquely represented as the sum of an even function and an odd function.

Essential norms of a potential theoretic boundary integral operator in L 1

Josef Král, Dagmar Medková (1998)

Mathematica Bohemica

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Let G ⊂ ℝ m ( m ≥ 2 ) be an open set with a compact boundary B and let σ ≥ 0 be a finite measure on B . Consider the space L 1 ( σ ) of all σ -integrable functions on B and, for each f ∈ L 1 ( σ ) , denote by f σ the signed measure on B arising by multiplying σ by f in the usual way. 𝒩 σ f denotes the weak normal derivative (w.r. to G ) of the Newtonian (in case m > 2 ) or the logarithmic (in case n = 2 ) potential of f σ , correspondingly. Sharp geometric estimates are obtained for the essential norms of the operator 𝒩 σ - α I (here α ∈ ℝ ...

Direct product decompositions of infinitely distributive lattices

Ján Jakubík (2000)

Mathematica Bohemica

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Let α be an infinite cardinal. Let 𝒯 α be the class of all lattices which are conditionally α -complete and infinitely distributive. We denote by 𝒯 σ ' the class of all lattices X such that X is infinitely distributive, σ -complete and has the least element. In this paper we deal with direct factors of lattices belonging to 𝒯 α . As an application, we prove a result of Cantor-Bernstein type for lattices belonging to the class 𝒯 σ ' .