Displaying similar documents to “ ω -compact elements of normed algebras”

Centralizers for subsets of normed algebras

Bertram Yood (2000)

Studia Mathematica

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Let G be the set of invertible elements of a normed algebra A with an identity. For some but not all subsets H of G we have the following dichotomy. For x ∈ A either c x c - 1 = x for all c ∈ H or s u p c x c - 1 : c H = . In that case the set of x ∈ A for which the sup is finite is the centralizer of H.

A theorem on isotropic spaces

Félix Cabello Sánchez (1999)

Studia Mathematica

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Let X be a normed space and G F ( X ) the group of all linear surjective isometries of X that are finite-dimensional perturbations of the identity. We prove that if G F ( X ) acts transitively on the unit sphere then X must be an inner product space.

A representation theorem for tense n × m -valued Łukasiewicz-Moisil algebras

Aldo Victorio Figallo, Gustavo Pelaitay (2015)

Mathematica Bohemica

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In 2000, Figallo and Sanza introduced n × m -valued Łukasiewicz-Moisil algebras which are both particular cases of matrix Łukasiewicz algebras and a generalization of n -valued Łukasiewicz-Moisil algebras. Here we initiate an investigation into the class n × m of tense n × m -valued Łukasiewicz-Moisil algebras (or tense LM n × m -algebras), namely n × m -valued Łukasiewicz-Moisil algebras endowed with two unary operations called tense operators. These algebras constitute a generalization of tense...

Singularity categories of skewed-gentle algebras

Xinhong Chen, Ming Lu (2015)

Colloquium Mathematicae

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Let K be an algebraically closed field. Let (Q,Sp,I) be a skewed-gentle triple, and let ( Q s g , I s g ) and ( Q g , I g ) be the corresponding skewed-gentle pair and the associated gentle pair, respectively. We prove that the skewed-gentle algebra K Q s g / I s g is singularity equivalent to KQ/⟨I⟩. Moreover, we use (Q,Sp,I) to describe the singularity category of K Q g / I g . As a corollary, we find that g l d i m K Q s g / I s g < if and only if g l d i m K Q / I < if and only if g l d i m K Q g / I g < .

Engel BCI-algebras: an application of left and right commutators

Ardavan Najafi, Arsham Borumand Saeid (2021)

Mathematica Bohemica

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We introduce Engel elements in a BCI-algebra by using left and right normed commutators, and some properties of these elements are studied. The notion of n -Engel BCI-algebra as a natural generalization of commutative BCI-algebras is introduced, and we discuss Engel BCI-algebra, which is defined by left and right normed commutators. In particular, we prove that any nilpotent BCI-algebra of type 2 is an Engel BCI-algebra, but solvable BCI-algebras are not Engel, generally. Also, it is...

Quantised 𝔰𝔩 2 -differential algebras

Andrey Krutov, Pavle Pandžić (2024)

Archivum Mathematicum

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We propose a definition of a quantised 𝔰𝔩 2 -differential algebra and show that the quantised exterior algebra (defined by Berenstein and Zwicknagl) and the quantised Clifford algebra (defined by the authors) of  𝔰𝔩 2 are natural examples of such algebras.

On area and side lengths of triangles in normed planes

Gennadiy Averkov, Horst Martini (2009)

Colloquium Mathematicae

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Let d be a d-dimensional normed space with norm ||·|| and let B be the unit ball in d . Let us fix a Lebesgue measure V B in d with V B ( B ) = 1 . This measure will play the role of the volume in d . We consider an arbitrary simplex T in d with prescribed edge lengths. For the case d = 2, sharp upper and lower bounds of V B ( T ) are determined. For d ≥ 3 it is noticed that the tight lower bound of V B ( T ) is zero.

Transfer of derived equivalences from subalgebras to endomorphism algebras II

Shengyong Pan, Jiahui Yu (2024)

Czechoslovak Mathematical Journal

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We investigate derived equivalences between subalgebras of some Φ -Auslander-Yoneda algebras from a class of n -angles in weakly n -angulated categories. The derived equivalences are obtained by transferring subalgebras induced by n -angles to endomorphism algebras induced by approximation sequences. Then we extend our constructions in T. Brüstle, S. Y. Pan (2016) to n -angle cases. Finally, we give an explicit example to illustrate our result.

Matrix representation of finite effect algebras

Grzegorz Bińczak, Joanna Kaleta, Andrzej Zembrzuski (2023)

Kybernetika

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In this paper we present representation of finite effect algebras by matrices. For each non-trivial finite effect algebra E we construct set of matrices M ( E ) in such a way that effect algebras E 1 and E 2 are isomorphic if and only if M ( E 1 ) = M ( E 2 ) . The paper also contains the full list of matrices representing all nontrivial finite effect algebras of cardinality at most 8 .

A F -algebras and topology of mapping tori

Igor Nikolaev (2015)

Czechoslovak Mathematical Journal

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The paper studies applications of C * -algebras in geometric topology. Namely, a covariant functor from the category of mapping tori to a category of A F -algebras is constructed; the functor takes continuous maps between such manifolds to stable homomorphisms between the corresponding A F -algebras. We use this functor to develop an obstruction theory for the torus bundles of dimension 2 , 3 and 4 . In conclusion, we consider two numerical examples illustrating our main results.