# Surreal number/Simple hackenbush

Surreal number (subpages/draftspace)

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The construction of surreal numbers with birthdays yields an obvious way to count the real dyadic numbers. Here we look at a plausibility argument for a pair of sequences of dyadic numbers that converge to , one from above, and one from below. I like plausibility arguments because sometimes you have to read an entire book to understand a proof.

*plausible*and

*useful*, I honestly don't care if it is true.

The parent page Surreal number described the subset of all surreal numbers associated with ordinary real numbers. Oddly, all such "real" surreal numbers includes the irrationals, despite the fact that this subset can be written as didactic rationals:

### Hackenbush

[edit | edit source]https://hackenbush.xyz/ w:Hackenbush

See also this MUST READ: [1] saved as Bartlett.pdf

#### Stalk rule

[edit | edit source]- Count the number of blue segments that are connected to the in one continuous path. If there are n of them, start with the number n.
- For each new segment going up, assign the value of that segment to be half of the one below it, and add it to the sum if it is blue, and subtract if it is red. :#When you reach the top of the stalk, that’s your final value.

- For example, consider the stalk whose segments are, starting from the ground: BBBRRBRRBR. We begin with 3 because of the three blue segments. The next red adds −1/2, the next red adds −1/4, the following blue adds +1/8, and so on. Thus the value for this stalk will be:

- 3 − 1/ 2 − 1/ 4 + 1/ 8 − 1 /16 − 1/ 32 + 1 /64 − 1/ 128

See also https://math.stackexchange.com/questions/556014/what-is-worth-of-a-stalk-in-red-blue-hackenbush

## References

[edit | edit source]- ω+1>ω is true

- 5 types of (tomrocksmaths.com)] (see also w:Transfinite number and w:Infinity plus one.)
- Surreal numbers are a real thing...(www.scientificamerican.com)
- Surreal_number_tree.svg
- w:Actual_infinity#Current_mathematical_practice

- ω+1>ω is false

- Is there such an ordinal as ω-1? There is an extension of ordinal numbers, the surreal numbers, that include ω−1, but let me give you two warnings about that. First, the addition of the surreal numbers is not exactly the same as ordinal addition. Second, I don't recommend reading about the surreal numbers until you get a better grasp of w:ordinal numbers.
- is-omega-1-finite

- I need to learn about

- Excellent site that mentions Dedekind cuts: https://thatsmaths.com/2012/11/22/the-root-of-infinity-its-surreal/
- Excellent simple answer: https://www.quora.com/What-are-surreal-numbers-in-laymans-terms
- https://math.stackexchange.com/questions/3652852/how-does-conways-proposed-compromise-for-constructing-the-real-numbers-actually
- Excellent explanation of addition https://issuu.com/oz1cz/docs/surreal