# How to reproduce the “old” Peano's symbol for set inclusion

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 ?

• 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. – Najib Idrissi Apr 27 '15 at 11:15
• @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 ... :) – Mauro ALLEGRANZA Apr 27 '15 at 11:29
• 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. – Najib Idrissi Apr 27 '15 at 11:31