3 ms·

I believe in German (possibly also other languages) the thunderbolt ↯ is commonly used to mean "this is a contradiction" in a mathematical proof, equivalently t

I believe in German (possibly also other languages) the thunderbolt ↯ is commonly used to mean "this is a contradiction" in a mathematical proof, equivalently to in English a kind of ⋕ rotated by 45° or the symbol ※. The symbol ⟂ on the other hand means "false" and is used in particular in formal logic.

froh 4y ago
Yes and no. Yes, we indeed used and afaict still use the thunderbolt for contradiction in my German university. However "perpendicular" and "bottom/falsum" are two different Unicode codepoints with very similar glyphs. https://en.m.wikipedia.org/wiki/Up_tack https://en.m.wikipedia.org/wiki/Up_tack