# Baby Sister Numbers

post by jefftk (jkaufman) · 2021-11-04T01:10:09.551Z · LW · GW · 28 commentsA few days ago, Lily (7y) told me about some Nora-inspired numbers:

The largest number is

.*Noranoo*If you try and make any larger number, you still get

. For example,*Noranoo*

, and*Noranoo*+ 1 =*Noranoo*

.*Noranoo** 2 =*Noranoo*Otherwise, it behaves normally. You can have

, dubbed "*Noranoo*- 1

". This means*Norklet*

, while*Noranoo*- 1 + 1 =*Noranoo*

. This didn't bother her.*Noranoo*+ 1 - 1 =*Norklet*

is*Noranoo** -1

. It is the smallest number, and like*Norahats*

any attempt to go lower keeps you at*Noranoo*

.*Norahats*These are very large numbers: much bigger than a googol.

This is a kind of saturation arithmetic, more of a computersy approach than a mathy one, since you give up associativity, distributivity, the successor function being an injection, and all that.

On the other hand, it's slightly more elegant than a typical
computational implementation of saturation, because it is symmetric
around zero. Normally, you are using some number of bits, which gives
you 2^N distinct values, and so an even number of integers. Typically
we set the minimum integer to be one larger, in absolute value, than
the maximum one. In this case, though, there are an odd number of integers.
I asked whether perhaps

could be *Norahats* * -1 * -1 * -1

and not
*Norklet*

, but Lily insisted that
*Noranoo*

and *Noranoo*

were
equal in magnitude.
*Norahats*

*Comment via: facebook*

## 28 comments

Comments sorted by top scores.

## comment by flowerfeatherfocus · 2021-11-05T14:25:09.594Z · LW(p) · GW(p)

This is great! It reminds me a bit of ordinal arithmetic, in which addition is non-commutative. The ordinal numbers begin with all infinitely many natural numbers, followed by the first infinite ordinal, . The next ordinal is , which is greater than . But is just .

Subtraction isn't canonically defined for the ordinals, so isn't a thing, but there's an extension of the ordinal numbers called the surreal numbers where it does exist. Sadly addition is defined differently on the surreals, and here it is commutative. does exist though, and as with

does equal .*Norahats*

The surreals also contain the infinitesimal number , which is greater than zero but less than any real number. it's defined as the number between on the left and all members of the infinite sequence on the right. Not exactly

(), but not too far away: :)*Norklet*

(h/t Alex_Altair, whose recent venture into this area caused me to have any information whatsoever about it in my head)

Replies from: Slider, jkaufman## ↑ comment by Slider · 2021-11-05T15:29:24.829Z · LW(p) · GW(p)

ω-1 does exist as a surreal and is way better direct analog for Norklet

Replies from: flowerfeatherfocus## ↑ comment by flowerfeatherfocus · 2021-11-06T01:41:31.704Z · LW(p) · GW(p)

Yeah, agreed :) I mentioned existing as a surreal in the original comment, though more in passing than epsilon. I guess the name Norklet more than anything made me think to mention epsilon--it has a kinda infinitesimal ring to it. But agreed that is a way better analog.

## ↑ comment by jefftk (jkaufman) · 2021-11-05T17:17:34.214Z · LW(p) · GW(p)

One big difference, I think, is that you can't get to ω by (finite) counting, but you can get to Noranoo?

Replies from: Slider## ↑ comment by Slider · 2021-11-06T01:04:24.979Z · LW(p) · GW(p)

That was mainly the motivation for my counting question but the answer isconsistent with Noranoo invoking transfinite induction to get counted.

I think the pattern of -"Is it possible to count to Noranoo?" -yes and -"Can I count to Noranoo?" -no would isolate only transfinite induction.

Another way this could be asked as a dad joke is if ever one is tired and being asked about it claim that "I spent the night counting to Noranoo". If this story is incredile then it is recognised as a supertask. If there is a reaction like "wow you count fast" that would point to it being some very high finite integer.

Replies from: jkaufman## ↑ comment by jefftk (jkaufman) · 2021-11-06T02:03:15.564Z · LW(p) · GW(p)

I mean, she may think that it is such a large number that it is unrealistic that I could count that high overnight? Or even in my lifetime?

For example, if you claimed to have counted to a googol overnight I wouldn't believe you, but it's still finite.

Replies from: Slider## ↑ comment by Slider · 2021-11-06T02:48:04.248Z · LW(p) · GW(p)

I guess I am trying to fish for a scneario that would prompt a resonpce that would clearly support that. Another approach that would more strongly differentiate against googol-likeness would be to start counting and then increasingly blur the words together and then slow down "... norklet, noranoo" the thinking going that even if your mouth was perfectly dexterous the counting might detect "cheating detection" as it migth not be respectful of the vastness of the number.

But to be frank it was more that I thought I kinda understood the difference but I find myself struggling to figure out what would be a fair operationalization, suggesting I don't understand it.

## comment by TLW · 2021-11-05T05:21:02.741Z · LW(p) · GW(p)

Is Noranoo a prime?

Is Norklet a prime?

Is the product of all primes below Noranoo, plus one, a prime?

What is the sum of all positive integers below Norklet?

## ↑ comment by jefftk (jkaufman) · 2021-11-05T12:33:37.507Z · LW(p) · GW(p)

I asked Lily, and she told me that Noranoo is even, so I guess it isn't prime. Norklet is odd, but she doesn't know what prime means so I don't have a good way to find out.

The product of all primes below Noranoo is (not asking Lily) Noranoo. (Because otherwise it would be greater than Noranoo, and so clamps to Noranoo)

The sum of all positive integers below Norklet is Noranoo, since again it clamps.

Replies from: vanessa-kosoy## ↑ comment by Vanessa Kosoy (vanessa-kosoy) · 2021-11-05T15:29:46.614Z · LW(p) · GW(p)

Noranoo is obviously even in the sense that Noranoo = 2 * Noranoo, although this doesn't imply that Norklet is odd

Replies from: jkaufman## ↑ comment by jefftk (jkaufman) · 2021-11-05T17:18:43.453Z · LW(p) · GW(p)

Lily is operationalizing "even" as "you can divide it into two piles that are the same size".

Since you can do this for Noranoo, you can't for Norklet.

Replies from: vanessa-kosoy## ↑ comment by Vanessa Kosoy (vanessa-kosoy) · 2021-11-05T18:37:07.723Z · LW(p) · GW(p)

Well, if we consider two piles of size Noranoo then the total size is still Noranoo, isn't it?

Replies from: jkaufman## ↑ comment by jefftk (jkaufman) · 2021-11-05T20:14:32.148Z · LW(p) · GW(p)

You can't have two piles each of size Noranoo; that's too big

Replies from: jkaufman## ↑ comment by jefftk (jkaufman) · 2021-11-06T12:43:58.757Z · LW(p) · GW(p)

(This was initially my interpretation, but after Lily woke up I asked her, and that was also her response)

## comment by tailcalled · 2021-11-04T22:08:57.801Z · LW(p) · GW(p)

Does Noranoo have a square root? Is the square root an integer?

Replies from: vanessa-kosoy, jkaufman## ↑ comment by Vanessa Kosoy (vanessa-kosoy) · 2021-11-05T18:38:25.040Z · LW(p) · GW(p)

Noranoo has many square roots since, for example, Noranoo * Noranoo = Noranoo.

Replies from: tailcalled## ↑ comment by tailcalled · 2021-11-05T20:34:44.554Z · LW(p) · GW(p)

True, I guess I meant a square root that doesn't overflow, though I'm not sure how to define that in an elegant way.

## ↑ comment by jefftk (jkaufman) · 2021-11-05T12:34:33.924Z · LW(p) · GW(p)

I don't know how to find out, since Lily doesn't understand square roots yet.

Replies from: tailcalled## ↑ comment by tailcalled · 2021-11-05T14:31:23.824Z · LW(p) · GW(p)

Maybe you could introduce it via areas? If you drew squares of different sizes and talked about the relationship between area and side lengths.

Replies from: jkaufman## ↑ comment by jefftk (jkaufman) · 2021-11-05T17:19:03.231Z · LW(p) · GW(p)

She doesn't have area yet either, sadly

## comment by Dagon · 2021-11-04T14:54:22.114Z · LW(p) · GW(p)

Is Norklet a regular integer? I'd think it has to be, unless there's a distinct counting system for distance from Noranoo (and Norahats). Which just means that this is regular numbers, but with an overflow policy of staying at the endpoint.

Replies from: Slider, jkaufman## ↑ comment by jefftk (jkaufman) · 2021-11-04T19:18:28.958Z · LW(p) · GW(p)

Is Norklet a regular integer?

Yes

regular numbers, but with an overflow policy of staying at the endpoint.

Yes

## comment by Slider · 2021-11-04T14:08:04.834Z · LW(p) · GW(p)

Can you get to Noranoo by +1 from 0?

Replies from: jkaufman## ↑ comment by jefftk (jkaufman) · 2021-11-04T19:17:48.743Z · LW(p) · GW(p)

Yes. If you start at zero and add 1 Noranoo times, you'll get Noranoo.

Replies from: Slider