Possible Duplicate:
How does one insert a backslash or a tilde (~) into LaTeX?
How can I write tilde ~ in math mode?

When I write $~$, I get a space. When I write $\~$, I get an error.

I am trying to write ~ to represent the equinumerous relation.

marked as duplicate by bloodworks, ArTourter, Scott H., Boris, egreg Jan 18 '13 at 22:45

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