T. Banakh, O. Pikhurko
On linear functorial operators extending pseudometrics

Comment.Math.Univ.Carolinae 38,2 (1997) 343-348.

Abstract:For a functor $F\supset Id$ on the category of metrizable compacta, we introduce a conception of a linear functorial operator $T=\{T_X:Pc(X)\to Pc(FX)\}$ extending (for each $X$) pseudometrics from $X$ onto $FX\supset X$ (briefly LFOEP for $F$). The main result states that the functor $SP^n_G$ of $G$-symmetric power admits a LFOEP if and only if the action of $G$ on $\{1,...,n\}$ has a one-point orbit. Since both the hyperspace functor $\exp $ and the probability measure functor $P$ contain $SP^2$ as a subfunctor, this implies that both $\exp $ and $P$ do not admit LFOEP.

Keywords: linear functorial operator extending (pseudo)metrics, the functor of $G$-symmetric power
AMS Subject Classification: 54B30, 54C20, 54E35