Showing papers by "Vlastimil Pták published in 1979"
01 Oct 1979
TL;DR: In this paper, it was shown that α may be replaced by |α|σ for all x ∈ A and some constant α is equivalent to [ x, a ]∈Rad a for all X ∈ a ; it is the purpose of the present note to investigate a related condition.
Abstract: In a recent paper ( 6 ) the present author has shown that, for an element a of a Banach algebra A , the condition for all x ∈ A and some constant α is equivalent to [ x , a ]∈Rad a for all x ∈ A ; it turns out that α may be replaced by |α|σ It is the purpose of the present note to investigate a related condition
22 citations
TL;DR: In this article, the authors considered the problem of finding among all contractions T on an n-dimensional Hilbert space whose spectral radius does not exceed a given number p T for which | T n | is maximum.
16 citations
2 citations