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On graph associated to co-ideals of commutative semirings

Yahya Talebi, Atefeh Darzi (2017)

Commentationes Mathematicae Universitatis Carolinae

Let R be a commutative semiring with non-zero identity. In this paper, we introduce and study the graph Ω ( R ) whose vertices are all elements of R and two distinct vertices x and y are adjacent if and only if the product of the co-ideals generated by x and y is R . Also, we study the interplay between the graph-theoretic properties of this graph and some algebraic properties of semirings. Finally, we present some relationships between the zero-divisor graph Γ ( R ) and Ω ( R ) .

On groups of similitudes in associative rings

Evgenii L. Bashkirov (2008)

Commentationes Mathematicae Universitatis Carolinae

Let R be an associative ring with 1 and R × the multiplicative group of invertible elements of R . In the paper, subgroups of R × which may be regarded as analogues of the similitude group of a non-degenerate sesquilinear reflexive form and of the isometry group of such a form are defined in an abstract way. The main result states that a unipotent abstractly defined similitude must belong to the corresponding abstractly defined isometry group.

On hereditary artinian rings and the pure semisimplicity conjecture: rigid tilting modules and a weak conjecture

José L. García (2014)

Colloquium Mathematicae

A weak form of the pure semisimplicity conjecture is introduced and characterized through properties of matrices over division rings. The step from this weak conjecture to the full pure semisimplicity conjecture would be covered by proving that there do not exist counterexamples to the conjecture in a particular class of rings, which is also studied.

On hereditary rings and the pure semisimplicity conjecture II: Sporadic potential counterexamples

José L. García (2015)

Colloquium Mathematicae

It was shown in [Colloq. Math. 135 (2014), 227-262] that the pure semisimplicity conjecture (briefly, pssC) can be split into two parts: first, a weak pssC that can be seen as a purely linear algebra condition, related to an embedding of division rings and properties of matrices over those rings; the second part is the assertion that the class of left pure semisimple sporadic rings (ibid.) is empty. In the present article, we characterize the class of left pure semisimple sporadic rings having finitely...

On Hom-spaces of tame algebras

Raymundo Bautista, Yuriy Drozd, Xiangyong Zeng, Yingbo Zhang (2007)

Open Mathematics

Let Λ be a finite dimensional algebra over an algebraically closed field k and Λ has tame representation type. In this paper, the structure of Hom-spaces of all pairs of indecomposable Λ-modules having dimension smaller than or equal to a fixed natural number is described, and their dimensions are calculated in terms of a finite number of finitely generated Λ-modules and generic Λ-modules. In particular, such spaces are essentially controlled by those of the corresponding generic modules.

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