Difference between revisions of "Involution"

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== Properties ==
 
== Properties ==
 
* An function is an involution [[iff]] it is symmetric about the line <math>f(x)=x</math> in the coordinate plane.
 
* An function is an involution [[iff]] it is symmetric about the line <math>f(x)=x</math> in the coordinate plane.
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Revision as of 18:48, 27 September 2008

An involution is a function whose inverse is itself.


Examples

  • The function $y(x)=x$ has the inverse $x(y)=y$, which is the same function, and thus $f(x)=x$ is an involution.
  • The logical NOT is an involution because $\neg \neg p} \equiv p$ (Error compiling LaTeX. Unknown error_msg).
  • The additive negation is an involution because $--x=x$.
  • The multiplicative inverse is an involution because $\frac{1}{\frac{1}{x}}=x$. In fact, for any $n \neq 0$, $f(x)=\frac{n}{x}$ is an involution.

Properties

  • An function is an involution iff it is symmetric about the line $f(x)=x$ in the coordinate plane.

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