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The three-space-problem for locally-m-convex algebras.

Susanne Dierolf, Thomas Heintz (2003)

RACSAM

We prove that a locally convex algebra A with jointly continuous multiplication is already locally-m-convex, if A contains a two-sided ideal I such that both I and the quotient algebra A/I are locally-m-convex. An application to the behaviour of the associated locally-m-convex topology on ideals is given.

The topological complexity of sets of convex differentiable functions.

Mohammed Yahdi (1998)

Revista Matemática Complutense

Let C(X) be the set of all convex and continuous functions on a separable infinite dimensional Banach space X, equipped with the topology of uniform convergence on bounded subsets of X. We show that the subset of all convex Fréchet-differentiable functions on X, and the subset of all (not necessarily equivalent) Fréchet-differentiable norms on X, reduce every coanalytic set, in particular they are not Borel-sets.

The topology of the Banach–Mazur compactum

Sergey Antonyan (2000)

Fundamenta Mathematicae

Let J(n) be the hyperspace of all centrally symmetric compact convex bodies A n , n ≥ 2, for which the ordinary Euclidean unit ball is the ellipsoid of maximal volume contained in A (the John ellipsoid). Let J 0 ( n ) be the complement of the unique O(n)-fixed point in J(n). We prove that: (1) the Banach-Mazur compactum BM(n) is homeomorphic to the orbit space J(n)/O(n) of the natural action of the orthogonal group O(n) on J(n); (2) J(n) is an O(n)-AR; (3) J 0 ( 2 ) / S O ( 2 ) is an Eilenberg-MacLane space 𝐊 ( , 2 ) ; (4) B M 0 ( 2 ) = J 0 ( 2 ) / O ( 2 ) is noncontractible;...

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