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On spectral continuity of positive elements

S. Mouton (2006)

Studia Mathematica

Let x be a positive element of an ordered Banach algebra. We prove a relationship between the spectra of x and of certain positive elements y for which either xy ≤ yx or yx ≤ xy. Furthermore, we show that the spectral radius is continuous at x, considered as an element of the set of all positive elements y ≥ x such that either xy ≤ yx or yx ≤ xy. We also show that the property ϱ(x + y) ≤ ϱ(x) + ϱ(y) of the spectral radius ϱ can be obtained for positive elements y which satisfy at least one of the...

On the construction and the realization of wild monoids

Pavel Růžička (2018)

Archivum Mathematicum

We develop elementary methods of computing the monoid 𝒱 ( R ) for a directly-finite regular ring R . We construct a class of directly finite non-cancellative refinement monoids and realize them by regular algebras over an arbitrary field.

On the distributive radical of an Archimedean lattice-ordered group

Ján Jakubík (2009)

Czechoslovak Mathematical Journal

Let G be an Archimedean -group. We denote by G d and R D ( G ) the divisible hull of G and the distributive radical of G , respectively. In the present note we prove the relation ( R D ( G ) ) d = R D ( G d ) . As an application, we show that if G is Archimedean, then it is completely distributive if and only if it can be regularly embedded into a completely distributive vector lattice.

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