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JOURNALS // Izvestiya Rossiiskoi Akademii Nauk. Seriya Matematicheskaya // Archive

Izv. RAN. Ser. Mat., 2025 Volume 89, Issue 3, Pages 230–240 (Mi im9610)

A criterion for the weak continuity of representations of topological groups in dual Fréchet spaces

A. I. Shternabc

a Lomonosov Moscow State University, Faculty of Mechanics and Mathematics
b Moscow Center for Fundamental and Applied Mathematics
c Scientific Research Institute for System Studies of RAS, Moscow

Abstract: Sufficient conditions are obtained for the weak continuity of representations of topological groups in Fréchet spaces that are dual to some locally convex spaces by operators adjoint to continuous linear operators in a predual space In particular, it is shown that a representation $\pi$ of a topological group $G$ on a Fréchet space $E$ dual to a locally convex space $E_*$ by adjoint operators is continuous in the weak$^*$ operator topology if, for some number $q$, $0\le q<1$, there is a neighbourhood $V$ of the neutral element $e$ of $G$ such that, for any neighbourhood $U$ of the zero element in $E$, for its polar $\mathring{U}$ in $E^*$, and for any vector $\xi$ in $U$ and any element $\varphi\in\mathring{U}$ the inequality $|(\pi(g)\xi-\xi)(\varphi)|\le q$ holds for each $g\in V$.

Keywords: locally convex space, polar, dual Fréchet space, topological group, weak$^*$ operator topology.

UDC: 517.986.4

MSC: 22A25

Received: 29.05.2024
Revised: 23.09.2024

DOI: 10.4213/im9610


 English version:
Izvestiya: Mathematics, 2025, 89:3, 644–653

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© Steklov Math. Inst. of RAS, 2026