Symbols:General

$$\not=, \not>, \not<, \not\geq, \not\leq, \not\in, \not\exists, \not\subseteq, \not\subset, \not\supseteq, \not\supset$$

"Negation". The above symbols all mean the opposite of the non struck through version of the symbol. For example, $$x \not\in S$$ means that $$x$$ is not an element of $$S$$. The slash through a symbol ($$/$$ ) can be used to reverse the meaning of essentially any mathematical symbol (especially relations), although it is used most frequently with those listed above. Note that $$\not\subsetneq$$ and $$\not\supsetneq$$ can be confusing due to the strike through of the symbol as a whole and the strike through of the equivalence bar on the bottom, and hence should likely be avoided.

The LaTeX code for negation is \not followed by the code for whatever symbol you want to negate. For example, \not \in will render $$\not\in$$

Note that several of the above relations also have their own LaTeX commands for their negations, for example \ne or \neq for \not =, and \notin for \not \in.

See Arithmetic and Algebra and Set Operations and Relations for the definitions of the symbols above.

Prime
$$x'$$

The symbol $$'$$ is a general indicator of "another version of" or "another type of" where the specific version or type that is being described is to be defined.

The symbol $$x'$$ is technically called "x prime", although colloquially referred to as some variant of "x dash" or "x tick" or whatever can be devised by the ingenuity of the reader.

The LaTeX code for $$x'$$ is x' or (the verbose version) x^{\prime}</tt>.