How do you pronounce the inverse of the $\in$ relation? How do you say $G\ni x$?

Solution 1:

Paul Halmos in How to write mathematics suggests to distinguish between "$G$ contains $x$" and "$G$ includes $x$", the former meaning $x\in G$ and the latter $x\subseteq G$. Mark seems to have the opposite intuition about "contains" and "includes". This shows that Halmos's idea apparently has not caught on.

On the other hand, it is rare that it is not absolutely clear from the context whether "$G$ contains $x$" means $x\subseteq G$ or $x\in G$. And mathematics is usually communicated in writing or spoken language together with something written on the blackboard or on paper. So I think it is ok to say "$G$ contains $x$" for $x\in G$.

Solution 2:

It is very ideosyncratic, but a text in which this is completely explicit is Theory of Value by Gerard Debreu, a classic in mathematical economics. I quote:

Corresponding to these two different concepts, two different symbols, $\subset$ and $\in$, and two different locutions, "is contained in" and "belongs to," are used. Two different verbs are therefore used here to read $\supset$ and $\ni$: for the former "contains," and for the latter "owns," the natural counterpart of "belongs to."

Needless to say, I have never seen or heared "owns" been used in this way somewhere else.