In this paper, we establish some new critical fixed point theorems for the sum $AB+C$ in a Banach algebra relative to the weak topology, where $frac{I-C}{A}$ allows to be noninvertible. In addition, a special class of Banach algebras will be considered.

In the present paper, we rst modify the concepts of weakly fuzzy boundedness, strongly fuzzy boundedness, fuzzy continuity, strongly fuzzy continuity and weakly fuzzy continuity. Then, we try to nd some relations by making a comparative study of the fuzzy norms of linear operators.

Let  $left{a_alpharight}_{alphain I}$ be a bounded net in a Banach algebra $A$ and $varphi$ a nonzero multiplicative linear functional on $A$. In this paper, we deal with the problem of when $|aa_alpha-varphi(a)a_alpha|to0$ uniformly for all $a$ in weakly compact subsets of $A$. We show that Banach algebras associated to locally compact groups such  as Segal algebras and $L^1$-algebras are resp...

A bounded linear operator between Banach spaces is called completely continuous if it carries weakly convergent sequences into norm convergent sequences. Isolated is a universal operator for the class of non-completely-continuous operators from L1 into an arbitrary Banach space, namely, the operator from L1 into `∞ defined by T0(f) = Z rnf dμ n≥0 , where rn is the nth Rademacher function. It is...

Let T : C(S) → C(S) be a bounded linear operator. We present a necessary and sufficient condition for the so-called Daugavet equation ‖Id+ T ‖ = 1 + ‖T ‖ to hold, and we apply it to weakly compact operators and to operators factoring through c0. Thus we obtain very simple proofs of results by Foiaş, Singer, Pe lczyński, Holub and others. If E is a real Banach space, let us say that an operator ...

Taking matrix as a synonym for a numerical function on the Cartesian product of two (in general, infinite) sets, a simple purely algebraic “reciprocity property” says that the set of rows spans a finite-dimensional space iff the set of columns does so. Similar topological reciprocity properties serve to define strongly compact and weakly compact matrices, featured in the well-known basic facts ...

‎in this paper‎, ‎we investigate some results on natural metrics on the $mu$-normal functions and meromorphic $q_p$-classes‎. ‎also‎, ‎these classes are shown to be complete metric spaces with respect to the corresponding metrics‎. ‎moreover‎, ‎compact composition operators $c_phi$ and lipschitz continuous operators acting from $mu$-normal functions to the meromorphic $q_p$-classes are characte...