A few notes on formal balls. (English) Zbl 1385.54009
Given a quasi-metric space \((X,d)\) the partial order of formal balls, \(B(X,d)\) consists of the sets \(X\times[0,\infty)\) ordered by \((x,r)\leq_d(y,s)\) iff \(d(x,y)\leq r-s\). This paper investigates the interplay between \((X,d)\) and \(B(X,d)\). The emphasis is on completeness properties of the quasi-metric versus continuity and algebraicity properties of the partial order. Useful tools are the various order topologies on \(B(X,d)\) and on \((X,d)\) with the order it inherits as the subset \(X\times\{0\}\) of \(B(X,d)\).
Reviewer: K. P. Hart (Delft)
MSC:
54E99 | Topological spaces with richer structures |
06B35 | Continuous lattices and posets, applications |
54E35 | Metric spaces, metrizability |