Editing If and only if (section)

===Notation===
The corresponding logical symbols are "<math>\leftrightarrow</math>", "<math>\Leftrightarrow</math>",<ref name=":2" /> and <math>\equiv</math>,<ref>{{Cite web|last=Weisstein|first=Eric W.|title=Equivalent|url=https://mathworld.wolfram.com/Equivalent.html|access-date=2020-09-04|website=mathworld.wolfram.com|language=en|archive-date=3 October 2020|archive-url=https://web.archive.org/web/20201003031516/https://mathworld.wolfram.com/Equivalent.html|url-status=live}}</ref> and sometimes "iff". These are usually treated as equivalent. However, some texts of [[mathematical logic]] (particularly those on [[first-order logic]], rather than [[propositional logic]]) make a distinction between these, in which the first, <math>\leftrightarrow</math>, is used as a symbol in logic formulas, while <math>\Leftrightarrow</math> or <math>\equiv</math> is used in reasoning about those logic formulas (e.g., in [[metalogic]]). In [[Jan Łukasiewicz|Łukasiewicz]]'s [[Polish notation]], it is the prefix symbol <math>E</math>.<ref>{{Cite web|url=https://plato.stanford.edu/entries/lukasiewicz/polish-notation.html|title=Jan Łukasiewicz > Łukasiewicz's Parenthesis-Free or Polish Notation (Stanford Encyclopedia of Philosophy)|website=plato.stanford.edu|access-date=2019-10-22|archive-date=9 August 2019|archive-url=https://web.archive.org/web/20190809092951/https://plato.stanford.edu/entries/lukasiewicz/polish-notation.html|url-status=live}}</ref>

Another term for the [[logical connective]], i.e., the symbol in logic formulas, is [[exclusive nor]].

In [[TeX]], "if and only if" is shown as a long double arrow: <math>\iff</math> via command \iff or \Longleftrightarrow.<ref>{{Cite web|url=https://artofproblemsolving.com/wiki/index.php/LaTeX:Symbols|title=LaTeX:Symbol|website=Art of Problem Solving|access-date=2019-10-22|archive-date=22 October 2019|archive-url=https://web.archive.org/web/20191022014053/https://artofproblemsolving.com/wiki/index.php/LaTeX:Symbols|url-status=live}}</ref>