In his Arithmetices Principia Novo Methodo Exposita (1889) [see this post Giuseppe Peano used an $\text {"inverted C"}$ for set inclusion (modern : $\subset$).

There is a way to "invert" the alphabetic letters in formulae ?

Thanks in advance

  • $\begingroup$ So Peano used $a \supset b$ to say "$a$ is contained in $b$", if I understand correctly? (That's confusing :/) Anyway, the command is \supset. $\endgroup$ Commented Apr 27, 2015 at 11:15
  • $\begingroup$ @NajibIdrissi - Thanks, but I know it ... In order to convey the "historical" aspect of the old symbols, I'm asking for a way to "ivert" (right-to-left) - if possible - some alphabetic symbols, like $C$ and $D$, used in that way by Peano and Russell ... :) $\endgroup$ Commented Apr 27, 2015 at 11:29
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    $\begingroup$ Ah, you literally want the symbol $C$ but flipped horizontally, without any other modifications? It's possible in latex (with \reflectbox), but I don't know if it is in mathjax. \reflectbox doesn't exist at least. $\endgroup$ Commented Apr 27, 2015 at 11:31
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    $\begingroup$ There is a way to rotate a box in LaTeX, and therefore you can rotate a C by 180 degrees. Further vertical and horizontal shifting might also be needed. tex.stackexchange.com/questions/93797/how-to-rotate-text-inline $\endgroup$ Commented Apr 27, 2015 at 11:45
  • $\begingroup$ Thanks @Najib ... $\endgroup$ Commented Apr 27, 2015 at 11:46
  • $\begingroup$ In MathJaX you can use unicode. Maybe U+2183 or U+2184 is similar to what you are looking for. en.wikipedia.org/wiki/Claudian_letters fileformat.info/convert/text/upside-down-map.htm Or maybe you can find some other unicode characters which will suit you. $\endgroup$ Commented Apr 27, 2015 at 12:30


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