Post #1765430

The Brouwer fixed point theorem in action, as exhibited by Github labels: If you try to define a continuous function from text colors to contrasting background colors, there will be some text colors whose background is the same as the text rather than contrasting with it. Discontinuity is necessary to avoid this. "Why some GitHub labels illegible", @MoritzFirsching, https://firsching.ch/github_labels, via https://mathstodon.xyz/@MoritzFirsching/110015890478886651 – see also https://en.wikipedia.org/wiki/Brouwer_fixed-point_theorem This is from 2023 so I suspect the specific buggy behavior is long fixed but the phenomenon will recur for any attempt like this one to define a formula using only continuous building blocks.