I'd like to propose following ligatures - `|-` as [turnstile](https://en.wikipedia.org/wiki/Turnstile_(symbol)) - `|=` as [double turnstile](https://en.wikipedia.org/wiki/Double_turnstile) - `_|_` as [bottom](https://en.wikipedia.org/wiki/Up_tack) They are often shown in [math document](https://en.wikipedia.org/wiki/Logical_consequence) and sometimes used in [Haskell](https://en.wikibooks.org/wiki/Haskell/Denotational_semantics#Bottom_and_Partial_Functions)