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Example

The set Q is infinite but countable: we can list all positive rationals in an infinite matrix that holds at position <i, j> the rational i+1/j+1:

1/1 1/2 1/3 1/4 ...
/ / /
2/1 2/2 2/3 ... ...
/ /
3/1 3/2 ... ... ...
/
4/1 ... ... ... ...
... ... ... ... ...

We can enumerate all elements in this matrix in a sequence f.


Author: Wolfgang Schreiner
Last Modification: December 7, 1999

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