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The existence of envelopes

Edgar E. Enochs, Overtoun M. G. Jenda, Jinzhong Xu (1993)

Rendiconti del Seminario Matematico della Università di Padova

The existence of relative pure injective envelopes

Fatemeh Zareh-Khoshchehreh, Kamran Divaani-Aazar (2013)

Colloquium Mathematicae

Let 𝓢 be a class of finitely presented R-modules such that R∈ 𝓢 and 𝓢 has a subset 𝓢* with the property that for any U∈ 𝓢 there is a U*∈ 𝓢* with U* ≅ U. We show that the class of 𝓢-pure injective R-modules is preenveloping. As an application, we deduce that the left global 𝓢-pure projective dimension of R is equal to its left global 𝓢-pure injective dimension. As our main result, we prove that, in fact, the class of 𝓢-pure injective R-modules is enveloping.

The fundamental theorem and Maschke's theorem in the category of relative Hom-Hopf modules

Yuanyuan Chen, Zhongwei Wang, Liangyun Zhang (2016)

Colloquium Mathematicae

We introduce the concept of relative Hom-Hopf modules and investigate their structure in a monoidal category ̃ ( k ) . More particularly, the fundamental theorem for relative Hom-Hopf modules is proved under the assumption that the Hom-comodule algebra is cleft. Moreover, Maschke’s theorem for relative Hom-Hopf modules is established when there is a multiplicative total Hom-integral.

The G -graded identities of the Grassmann Algebra

Lucio Centrone (2016)

Archivum Mathematicum

Let G be a finite abelian group with identity element 1 G and L = g G L g be an infinite dimensional G -homogeneous vector space over a field of characteristic 0 . Let E = E ( L ) be the Grassmann algebra generated by L . It follows that E is a G -graded algebra. Let | G | be odd, then we prove that in order to describe any ideal of G -graded identities of E it is sufficient to deal with G ' -grading, where | G ' | | G | , dim F L 1 G ' = and dim F L g ' < if g ' 1 G ' . In the same spirit of the case | G | odd, if | G | is even it is sufficient to study only those G -gradings such that...

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