Free complex Banach lattices

The construction of the free Banach lattice generated by a real Banach space is extended to the complex setting. It is shown that for every complex Banach space E there is a complex Banach lattice ${\text{FBL}}_{\mathbb{C}}[E]$ containing a linear isometric copy of E and satisfying the following universal property: for every complex Banach lattice $X_{\mathbb{C}}$, every operator $T:E\to X_{\mathbb{C}}$ admits a unique lattice homomorphic extension $\stackrel{?}{T}:{\text{FBL}}_{\mathbb{C}}[E]\to X_{\mathbb{C}}$ with $6\stackrel{?}{T}6=6T6$. The free complex Banach lattice ${\text{FBL}}_{\mathbb{C}}[E]$ is shown to have analogous properties to those of its real counterpart. However, examples of non-isomorphic complex Banach spaces E and F can be given so that ${\text{FBL}}_{\mathbb{C}}[E]$ and ${\text{FBL}}_{\mathbb{C}}[F]$ are lattice isometric. The spectral theory of induced lattice homomorphisms on ${\text{FBL}}_{\mathbb{C}}[E]$ is also explored.     

Some approximation properties of Banach spaces and Banach lattices

The notion of the bounded approximation property = BAP (resp. the uniform approximation property = UAP) of a pair [Banach space, its subspace] is used to prove that if X is a ℒ _∞-space, Y a subspace with the BAP (resp. UAP), then the quotient X/Y has the BAP (resp. UAP). If Q: X → Z is a surjection, X is a ℒ ₁-space and Z is a ℒ _p -space (1 ≤ p ≤ ∞), then ker Q has the UAP. A complemented subspace of a weakly sequentially complete Banach lattice has the separable complementation property = SCP. A criterion for a space with GL-l.u.st. to have the SCP is given. Spaces which are quotients of weakly sequentially complete lattices and are uncomplemented in their second duals are studied. Examples are given of spaces with the SCP which have subspaces that fail the SCP. The results are applied to spaces of measures on a compact Abelian group orthogonal to a fixed Sidon set and to Sobolev spaces of functions of bounded variation on ℝ ⁿ .     

Dual banach lattices and Banach lattices with the Radon-Nikodym property

We construct a separable dual Banach latticeE such that no non-trivial order interval of its dual is weakly compact. HenceE has the Radon-Nikodym property without being in some sense a dual in a natural way. The final draft of this paper was written while the author held a grant from NATO to visit the Ohio State University.     

Compact operators in Banach lattices

Disjoint sequence methods from the theory of Riesz spaces are used to study compact operators on Banach lattices. A principal new result of the paper is that each positive map from a Banach latticeE to a Banach latticeF with compact majorant is itself compact provided the norms onE′ andF are order continuous.     

Projectors in certain Banach lattices

A generalization is given of the familiar result of Philips on the nonexistence of a projector from m onto c₀. The results obtained imply, for example, the following consequence. Ifthe Orlicz space L _M ^* E_M, there is no projector from L _M ^* onto E_M and E_M is not isomorphic to any conjugate Banach space.Translated from Matematicheskie Zametki, Vol. 4, No. 1, pp. 41–44, July, 1968.     

On Banach lattices of operators

Let Λ₁ and Λ₂ be infinte-dimensional, Banach lattices such thatc _o is not finitely representable in Λ₂. Then the bounded linear operators from Λ₁ to Λ₂ form a lattice if and only if Λ₁ is an abstract AL space.