We describe a construction which yields unbounded derivations

and strongly continuous one-parameter automorphism groups of certain

group C*-algebras. As an application, we show that a simple C*-algebra can

have an automorphism...

In this note we show that any derivation of a simple C*-algebra,

whose range is not dense, is closable. We also derive a necessary and sufficient condition

for a *-derivation of a C*-algebra, which is defined on the domain of a closed...

In this note we review briefly the subject of bounded and unbounded derivations

of operator algebras (C?-and W?-algebras). In particular, we mention some results on closability

and continuity of such derivations. ...

It is known that a C * -algebra A is amenable if and only if U(A), the unitary group of A, is amenable. We show the same result for A * -algebras with bounded unitary group and we prove in general that any amenable A * -algebras has amenable unitary...

s. ota proved that if δ is a closed *-derivation

Let A be an algebra. A linear mapping δ : A → A is called a derivation if δ(ab) = δ(a)b + aδ(b)

for each a, b ∈ A. Given two derivations δ and δ 0 on a C ∗ -algebra A, we prove that there exists a

derivation ∆ on A such that δδ0 = ∆2...

is amenable if and only if there exists a right invariant mean on WLUC(I), we also show that if A is a unital C * -algebra with isometry semigroup S, A is amenable if and only if there exists a right invariant mean on LUC(S)....

$(\\\\sigma,\\\\tau)$-derivations, we investigate the relation between

amenability and $(\\\\sigma,\\\\tau)$-amenability of Banach algebras in

the case when $\\\\sigma, \\\\tau$ are homomorphisms. We prove that if

$\\\\mathfrak A$ is a $C^*$-algebra and $\\\\sigma...

In this paper, we introduce generalizations of the Bessel inequality in Hilbert spaces

according to the results given by Bombiari, Boas–Bellman and Mitrinovi´c–Peˇcari´c–Fink and

give some extensions of these ...