Involutions with fixed points in 2-Banach spaces.
Irreducible Compact Operators.
Irregular convex sets with fixed-point property for nonexpansive mappings
Is an operator on weak which commutes with translations a convolution ?
Ishikawa iteration process with errors for nonexpansive mappings.
Ishikawa iteration process with errors for nonexpansive mappings in uniformly convex Banach spaces.
Ishikawa iterative process for a pair of single-valued and multivalued nonexpansive mappings in Banach spaces.
Ishikawa iterative process with errors for generalized Lipschitzian and Phi-accretive mappings in uniformly smooth Banach spaces
Ishikawa iterative sequence for the generalized Lipschitzian and Phi-strongly accretive mappings in Banach spaces
Ishikawa iterative sequence with errors for strongly pseudocontractive operators in arbitrary Banach spaces.
Isolated points of some sets of bounded cosine families, bounded semigroups, and bounded groups on a Banach space
We show that if the set of all bounded strongly continuous cosine families on a Banach space X is treated as a metric space under the metric of the uniform convergence associated with the operator norm on the space 𝓛(X) of all bounded linear operators on X, then the isolated points of this set are precisely the scalar cosine families. By definition, a scalar cosine family is a cosine family whose members are all scalar multiples of the identity operator. We also show that if the sets of all bounded...
Isolated points of spectrum of k-quasi-*-class A operators
Let T be a bounded linear operator on a complex Hilbert space H. In this paper we introduce a new class, denoted *, of operators satisfying where k is a natural number, and we prove basic structural properties of these operators. Using these results, we also show that if E is the Riesz idempotent for a non-zero isolated point μ of the spectrum of T ∈ *, then E is self-adjoint and EH = ker(T-μ) = ker(T-μ)*. Some spectral properties are also presented.
Isometric composition operators on weighted Dirichlet space
We investigate isometric composition operators on the weighted Dirichlet space with standard weights , . The main technique used comes from Martín and Vukotić who completely characterized the isometric composition operators on the classical Dirichlet space . We solve some of these but not in general. We also investigate the situation when is equipped with another equivalent norm.
Isometric parts of operators and the critical exponent
Isometries and automorphisms of the spaces of spinors.
The relationships between the JB*-triple structure of a complex spin factor S and the structure of the Hilbert space H associated to S are discussed. Every surjective linear isometry L of S can be uniquely represented in the form L(x) = mu.U(x) for some conjugation commuting unitary operator U on H and some mu belonging to C, |mu|=1. Automorphisms of S are characterized as those linear maps (continuity not assumed) that preserve minimal tripotents in S and the orthogonality relations among them.
Isometries between groups of invertible elements in Banach algebras
We show that if T is an isometry (as metric spaces) from an open subgroup of the group of invertible elements in a unital semisimple commutative Banach algebra A onto a open subgroup of the group of invertible elements in a unital Banach algebra B, then is an isometrical group isomorphism. In particular, extends to an isometrical real algebra isomorphism from A onto B.
Isometries in , generating functions and extremal problems
Isometries of Musielak-Orlicz spaces II
A characterization of isometries of complex Musielak-Orlicz spaces is given. If is not a Hilbert space and is a surjective isometry, then there exist a regular set isomorphism τ from (T,Σ,μ) onto itself and a measurable function w such that U(f) = w ·(f ∘ τ) for all . Isometries of real Nakano spaces, a particular case of Musielak-Orlicz spaces, are also studied.
Isometries of Orlicz Spaces of Vector Valued Functions.
Isometries of the unitary groups in C*-algebras
We give a complete description of the structure of surjective isometries between the unitary groups of unital C*-algebras. While any surjective isometry between the unitary groups of von Neumann algebras can be extended to a real-linear Jordan *-isomorphism between the relevant von Neumann algebras, this is not the case for general unital C*-algebras. We show that the unitary groups of two C*-algebras are isomorphic as metric groups if and only if the C*-algebras are isomorphic in the sense that...