 Constructive mathematicians initially concentrated their efforts on the field of analysis, with considerable success—witness the wealth of functional analysis developed in Bishop [1967]. This does not mean that, for example, algebra has been sidelined from the constructive enterprise: the material in the monograph by Mines et al [1986] can be regarded as a substantial algebraic counterpart to the constructive analysis carried out by Bishop. Much more recently, Lombardi and Quitté [2011] have published the first large volume of a proposed two-volume work on constructive algebra. However, not being expert in algebra, and being aware of the danger of making this article too long to hold the reader’s attention, we choose not to discuss constructive analysis or algebra in any detail; rather, in the following supplementary document, we turn to constructive topology, describing some rather different approaches to that subject: