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On Biprojectivity and Biflatness of Banach Algebras

M. Ghorbani, H. Rahimi


Biprojectivity and biflatness of Banach algebras are investigated in this paper. In particular we characterize the biprojectivity and biflatness of quotient Banach algebras by introducing the new notions of biprojectivity and biflatness modulo an ideal of Banach algebras. As
an application, by using the presented results we give a version of Helemskii’s theorem for semigroup Banach algebras.


Banach algebra, semigroup algebra, biprojectivity, biflatness

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