Donald Knuth: Surreal Numbers [video]
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I wonder how many ideas and insights have been lost throughout history to this phenomenon.
Sometimes you crack a problem from an unexpected angle and an entire forest of insights fall down onto you. You take a minute to type the first one but already some of the others are lost forever. Plus you broke out from the free flowing zone.
Will we ever come up with a tool to fix this tragedy?
http://quantifiedself.com/2009/09/the-social-memex/
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Relevant excerpt from The Mars Trilogy by Kim Stanley Robinson:
"Actually, now that he thought of it, losing his train of thought had been happening a lot. Or so he seemed to remember. It was an odd problem that way. But certainly he had been aware of losing trains of thought, which seemed, in their blank aftermath, to have been good thoughts. He had even tried to talk into his wrist pad when such an accelerated burst of thinking began, when he felt that sense of several strands braiding together to make something new. But the act of talking stopped the mentation. He was not a verbal thinker, it seemed; it was a matter of images, sometimes in the language of math, sometimes in some kind of inchoate flow that he could not characterise. So talking stopped it. Or else the lost thoughts were much less impressive than they had felt; for the wrist recordings had only a few phrases, hesitant, disconnected, and most of all slow – they were nothing like the thoughts he had hoped to record, which, especially in this particular state, were just the reverse – fast, coherent, effortless – the free play of the mind. That process could not be captured; and it struck Sax forcibly how little of anyone’s thinking was ever recorded or remembered or conveyed in any way to others – the stream of one’s consciousness never shared except in thimblefuls, even by the most prolific mathematician, the most diligent diarist."
Among authors alone, I would imagine we've lost a great many brilliant books because brainstorming is tricky and variable. Some days you get nothing, some days you get a dozen ideas and only one makes it out to the rest of the world.
I can't think of a good answer. Meditation and memory training might help, but are not silver bullets. Typing tends to be flow breaking (though I'm sure smartphones have improved matters) and vocalization is slow and awkward. It's hard to imagine anything short of EEG-translation removing the I/O limits on the mind.
I've been using the voice recorder on my phone to capture inspiration for years now (plus journals, ambient recordings, etc). I've got 1,700 recordings now, and whenever I dive deep into a new project I listen through the relevant ones for help.
Imagine that you have a high resolution, high fps camera. To record its feed requires a memory card that is capable of handling the data rate that the camera produces. Otherwise, the events captured by the camera are lost forever as they are flushed away by the forthgoing frames. Essentially, the problem boils down to the ability to encode the information at least as quickly as the lifetime of the information.
I believe the same thing happens in thought. We have a state of mind, an idea, that we want to share. Because we can't simply transfer whole brain states between each of us, we first need to serialize our ideas in writing or speech. That process is lossy, and possibly lengthy (or at least longer than your train of thought). In the mean time, a variety of new thoughts come to your mind, flushing the original idea.
So following this analogy, a solution to the problem of lost ideas would be to have higher bandwidth means of expressing and recording ideas. Personally this problem annoys me quite a lot in a variety of incarnations, and I think advances in Human Computer Interactions will directly address this.
For instance, consider a program. Sometimes I have a full blown picture of the program I want to build in mind. Then along the many hours it takes to serialize this into a programming language, I battle myself, attempting to keep the idea fresh. There many steps along the way that contribute to the serialization cost:
- The abstractions of the programming language.
- The step from "programming language" to "abstract syntax tree".
- The letters I have to type.
- The movement of my fingers on the keyboard.
- The translation of my brain from program construct, to
structure, to sentences, to words, to tokens, to letters,
to movement of my fingers, to keypresses.
There's many steps in this process that could potentially be removed to reduce the cost of serialization. * * *
So yes, I think this is a real problem, and I think that it can be addressed with better tools and techniques.>In 1967, writing in French, Pierre Jullien [9] generalized the concept of an ordinal slightly to what he called a “surordinal.” He announced several results, among which is the statement that the class of “surordinaux” are wqo.
>9. P. JULLIEN, Theorie des relations. - Sur la comparaison des types d’ordres disperses, C. R. Acad. Sci. Paris, Se’r. A 264 (1967), 594-595.
Youtube comments suck, can't even get paragraphs formatted normally.
https://archive.org/details/SurrealNumbers
By the way: does any one know whether all downloads on archive.org can be considered legal? It is amazing how many old books which, however, aren't old enough to be out of copyright can be found on that site.
day9 (an esports personality, with a math degree) tells the story of graham's number and how donald knuth invented up arrow notation for graham's number to be possible.
He tells it quite entertainingly with a great ending. (I was just showing this to a coworker this morning).
p.s. Re. "worked for 6 days and rested on the sevent" and "J.H.W.H." -- woah there cowboys. Get ye down to earth. ;)
This total order is also very useful. Namely one can associate surreal numbers to positions of a large class of two-player games. The sign of the associated surreal number (whether it's positive, zero, or negative) then tells you which player possesses a winning strategy. See https://en.wikipedia.org/wiki/Surreal_number#Application_to_... for more information on this point.
By definition! He was discussing ordering a mix e.g. π-sn, π, π+sn, π+smallestRealNumber.
Look, taking on one or the other of Conway or Knuth on a topic like this would be a sobering prospect, but both of them at once? Maybe you should be phrasing your "objections" in the form of questions.
How can one meaningfully speak of comparative measure between constructs that occupy distinct dimensional spaces. Question mark. (point well taken! :)
Because there is only a colloquial, not a mathematical, relationship between the notion of order, and most notions of dimension. An 'order' is any binary relation obeying certain properties (antisymmetry, transitivity, and, depending on whether you want a strict order, possibly irreflexivity); one can put an order on a set without any concern about whether it obeys your or anyone's intuition, as long as it satisfies those properties.
Unfortunately, I'm not sure how to define the notions of "approximate topological-ness" or "approximate geometric-ness" of an order in any rigorous way, so I am reluctant to answer the question. I would agree that trying to fit the order on the surreal numbers into an existing geometric, or even probably topological, intuition is likely to fail. For me, the order is in some sense a combinatorial construction; but I don't know any way to make that rigorous other than that the definition is game-theoretic, and I think of game theory as a particular kind of combinatorics (as probably no specialist in either field ever would).
By the way, after having noticed that the conversation in https://news.ycombinator.com/item?id=11952290 tended to involve frequent (what seemed to me to be) appeals to authority, which I think do not belong in mathematical discussion, I wanted to thank you for your measured tone: not "don't question these lofty personalities", but rather explicitly "do question them" (rather than assuming out of hand that an apparent objection is an actual one).
A mix of real and complex numbers is just a set of complex numbers, because every real number is a complex number. And complex numbers do not possess a total ordering: https://proofwiki.org/wiki/Complex_Numbers_cannot_be_Totally...
The set of complex numbers does not possess a total ordering that respects the algebraic operations. The set of complex numbers is in bijection (in many, meaningless, ways) with the set of real numbers, and so certainly admits a (indeed many, meaningless) total ordering.
Actually surreal numbers have a well-defined partial order despite the dimensionality concerns; keep in mind surreal numbers are a class, not a set. (They contain as a strict subclass the transfinite ordinals, so it must be a class).
Moreover I think the form <:> is best considered an operator (or generator) than a cartesian product. You can put a set of surreals on one side of <:> and out pops another surreal.
> In mathematics, the surreal number system is an arithmetic continuum containing the real numbers as well as infinite and infinitesimal numbers, respectively larger or smaller in absolute value than any positive real number. The surreals share many properties with the reals, including a total order ≤ and the usual arithmetic operations (addition, subtraction, multiplication, and division); as such, they form an ordered field.
The original context is different but I wonder if we can ever compute all the wealth and impact that has been created by the practitioners of his art.
What are the important/fun/etc. conjectures?
The definition of a surreal number requires that everything on the left set be less than everything in the right set, but 0 is not less than 0 , so {0|0} does not name a surreal number.
Games do not have this restriction.
The surreal numbers form a field (except that it has a proper class of elements instead of a set of elements) , while the Games do not form a field. The Games do however form a group under addition iirc. Yes, that seems true to me.
The Games represent all perfect information 2 player games with what is iirc called the normal play condition (i.e. you lose iff it is your turn and you have no valid moves), and are such that there is no sequence of moves by the 2 players such that the game never ends.
(Chess for example, is almost a Game , except that it is possible to reach a draw in chess, and the win conditions are somewhat different.
Tic-Tac-Toe with the change that, instead of winning when you have 3 in a row, you win when it is the other player's turn and they have no valid moves, and you cannot move if the other player has 3 in a row, is a Game in this sense.)
Note: I think that Games is often capitalized because of it being a proper class, but I am not sure.
It was so nonchalant it was just thrown in as if he was describing the napkin with the theory on it:
https://youtu.be/mPn2AdMH7UQ?t=5m31s
"Because we liked to have an affair in the hotel room."
"So that was the plan."