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*Idea*:

- Representation: let
<
`a`,`b`> denote the difference between`a`and`b`. - Normalize: <
`a`, 0_{N}> for non-negative ints, <0_{N},`a`> for negative ones.

Z:=Z_{ >= 0}unionZ_{< 0};Z_{ >= 0}:= {<x, 0_{N}>:xinN};Z_{< 0}:= {<0_{N},x>:xinN\{0_{N}}};

Constructor function:

I: NxN->ZI( x,y) :=ifx>=_{N}ythen<x-_{N}y, 0_{N}>else<0_{N},y-_{N}x>;

Author: Wolfgang Schreiner

Last Modification: November 16, 1999