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I was wondering if definitions in mathematics are "if and only" statements?

I know for sure that theorems are not "iff" statements.

Thank you in advance for your help.


marked as duplicate by user137731, drhab, Matthew Towers, Community Dec 11 '15 at 15:48

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  • $\begingroup$ Yes, they are. But usually only "if" is used. $\endgroup$ – drhab Dec 11 '15 at 15:46

Yes, any definition is a 'iff' statement, though we use just 'if' in definition.


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