Notes on q-normed Spaces in Constructive Analysis

Abstract

What we call q-normed (linear) spaces were introduced (under the name pseudonormed spaces) into constructive analysis by D.L. Johns as a means of handling spaces, such as L-infinity, in which not all elements are constructively normable. We prove a number of q-normed-space analogues/generalisations of standard theorems in the constructive analysis of normed linear spaces, and give examples showing that analogues of two of those theorems are essentially nonconstructive.