# Turn off ZeroDivisionError?

Steven D'Aprano steve at REMOVE-THIS-cybersource.com.au
Sun Feb 17 03:39:12 CET 2008

```On Sat, 16 Feb 2008 17:47:39 -0800, Mark Dickinson wrote:

> I've no clue where your (Steven's) idea that 'all ordinals are surreal
> numbers' came from.  They're totally unrelated.

Tell that to John Conway.

[quote]
Just as the *real* numbers fill in the gaps between the integers, the
*surreal* numbers fill in the gaps between Cantor's ordinal numbers. We
get them by generalizing our use of the {|} notation for the ordinal
numbers.
[...]
The ordinal numbers are those where there aren't any numbers to the right
of the bar:

{|} = 0, the simplest number of all
{0|} = 1, the simplest number greater than 0
{0,1|} = 2, the simplest number greater than 1 (and 0)

and so on.
[end quote]

"The Book of Numbers", John W Conway and Richard K Guy, Copernicus Books,
1996, p.283.

I trust I don't have to explain this to Mark, but for the benefit of
anyone else reading, Conway invented surreal numbers.

--
Steven

```