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\leftline{Mathematics 243 -- Algebraic Structures}
\leftline{Definitions Quiz 3 -- September 21, 2012}
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\leftline{Your Name: $\underline{\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ }$}
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A) (5) What does it mean for $f : A \to A$ to be a {\it permutation} of $A$? 

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B) (5) Is $f : {\bf Z} \to {\bf Z}$ defined by 
$$f(x) = \cases{x & if $x < 0$ \cr
                x-1 & if $x \ge 0$\cr}$$
a permutation of ${\bf Z}$?  Why or why not? 
\bye
