Commit 2021-06-23 17:29 dd5074c4
View on Github →feat(analysis/normed_space/basic): add has_nnnorm (#7986)
We create here classes has_nndist and has_nnnorm that are variants of has_dist and has_norm taking values in ℝ≥0.  Obvious instances are pseudo_metric_space and semi_normed_group.
These are not used that much in mathlib, but for example has_nnnorm is quite convenient for LTE.