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For writing cases like a definition of a function having two or more conditions compiled by large braces ({), do I have to use \begin{equation} and \begin{cases} within, or there is some other command which can be used even inside $$ ... $$ ?

marked as duplicate by Gonzalo Medina, dustin, mafp, Werner, Heiko Oberdiek Aug 4 '13 at 21:35

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