,ABSTRACT. There is a formula (Gelfand’s formula) to find the spectral radius of a linear operator defined on a Banach space. That formula does not apply even in normed spaces which are not complete. In this paper we show a formula to find the spectral radius of any linear and compact operator T defined on a complete topological vector space, locally convex. We also show an easy way to find a n...

A hypergroup is roughly speaking a locally compact Hausdorff space which has enough structure so that a convolution on the corresponding vector space of Radon measures makes it a Banach algebra. Hypergroups generalize in many ways topological groups. In this paper we extend to compact not necessarily commutative hypergroups some basic techniques on multipliers set forth for compact groups in He...

Each space C N = {f ∈ C c (R) : sptf ⊂ [−N,N ]} ⊂ C[−N,N ] is strictly smaller than the space C[−N,N ] of all continuous functions on the interval [−N,N ], since functions in C N must vanish at the endpoints. Still, C o N is a closed subspace of the Banach space C [−N,N ] (with sup norm), since a sup-norm limit of functions vanishing at ±N must also vanish there. Thus, each individual C N is a ...

We study the local topological structure of generic multijet preimages of algebraic varieties and prove their stratifiability with additional quantitative estimates. The result is a necessary technical tool for analyzing bifurcations of periodic orbits from heteroclinic polygons of vector fields in space. The proof is based on interpretation of Newton interpolation formula as a resolution of si...

We prove that a continuous linear operator T on a topological vector space X with weak topology is mixing if and only if the dual operator T ′ has no finite dimensional invariant subspaces. This result implies the characterization of hypercyclic operators on the space ω due to Herzog and Lemmert and implies the result of Bayart and Matheron, who proved that for any hypercyclic operator T on ω, ...

In this paper, we first present a new type of the concept of open sets by expressing some properties of arbitrary mappings on a power set. With the generalization of the closure spaces in categorical topology, we introduce the generalized topological spaces and the concept of generalized continuity and become familiar with weak and strong structures for generalized topological spaces. Then, int...

Theorem 1.4. Let X be a tvs and let F be a local base at 0. Then (i) U, V ∈ F ⇒ there exists W ∈ F such that W ⊆ U ∩ V . (ii) If U ∈ F , there exists V ∈ F such that V + V ⊆ U . (iii) If U ∈ F , there exists V ∈ F such that αV ⊆ U for all α ∈ K such that |α| ≤ 1. (iv) Any U ∈ J is absorbing, i.e. if x ∈ X, there exists δ > 0 such that ax ∈ U for all a such that |a| ≤ δ. Conversely, let X be a l...