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On a weak Freudenthal spectral theorem

Marek Wójtowicz (1992)

Commentationes Mathematicae Universitatis Carolinae

Let X be an Archimedean Riesz space and 𝒫 ( X ) its Boolean algebra of all band projections, and put 𝒫 e = { P e : P 𝒫 ( X ) } and e = { x X : x ( e - x ) = 0 } , e X + . X is said to have Weak Freudenthal Property ( WFP ) provided that for every e X + the lattice l i n 𝒫 e is order dense in the principal band e d d . This notion is compared with strong and weak forms of Freudenthal spectral theorem in Archimedean Riesz spaces, studied by Veksler and Lavrič, respectively. WFP is equivalent to X + -denseness of 𝒫 e in e for every e X + , and every Riesz space with sufficiently many projections...

On algebra homomorphisms in complex almost f -algebras

Abdelmajid Triki (2002)

Commentationes Mathematicae Universitatis Carolinae

Extensions of order bounded linear operators on an Archimedean vector lattice to its relatively uniform completion are considered and are applied to show that the multiplication in an Archimedean lattice ordered algebra can be extended, in a unique way, to its relatively uniform completion. This is applied to show, among other things, that any order bounded algebra homomorphism on a complex Archimedean almost f -algebra is a lattice homomorphism.

On extensions of orthosymmetric lattice bimorphisms

Mohamed Ali Toumi (2013)

Mathematica Bohemica

In the paper we prove that every orthosymmetric lattice bilinear map on the cartesian product of a vector lattice with itself can be extended to an orthosymmetric lattice bilinear map on the cartesian product of the Dedekind completion with itself. The main tool used in our proof is the technique associated with extension to a vector subspace generated by adjoining one element. As an application, we prove that if ( A , * ) is a commutative d -algebra and A 𝔡 its Dedekind completion, then, A 𝔡 can be equipped...

On invariant elements for positive operators.

R. Zaharopol (1997)

Revista Matemática de la Universidad Complutense de Madrid

In the paper we study the existence of nonzero positive invariant elements for positive operators in Riesz spaces. The class of Riesz spaces for which the results are valid is large enough to contain all the Banach lattices with order continuous norms. All the results obtained in earlier works deal with positive operators in KB-spaces and in many of them the approach is based upon the use of Banach limits. The methods created for KB-spaces cannot be extended to our more general setting; that is...

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