現代数学の系譜工学物理雑談古典ガロア理論も読む46

[過去ﾛｸﾞ] 現代数学の系譜工学物理雑談古典ガロア理論も読む46 (692ﾚｽ)
上下前次1-新
通常表示 512ﾊﾞｲﾄ分割ﾚｽ栞
抽出解除ﾚｽ栞

このｽﾚｯﾄﾞは過去ﾛｸﾞ倉庫に格納されています｡
次ｽﾚ検索歴削→次ｽﾚ栞削→次ｽﾚ過去ﾛｸﾞﾒﾆｭｰ

ﾘﾛｰﾄﾞ規制です｡10分ほどで解除するので､他のﾌﾞﾗｳｻﾞへ避難してください｡

479: 現代数学の系譜 雑談 古典ガロア理論も読む ◆e.a0E5TtKE  [sage] 2017/11/22(水) 19:16:31.41 ID:mEHYOxL2

>>478 つづき

そのために、Taylor先生達の本と論文から、下記関連事項を３つ引用する。

(>>44-45より)
https://pdfs.semanticscholar.org/8514/a9f8b30546ea81739b9409132673276713d3.pdf
[成書]The Mathematics of Coordinated Inference: A Study of Generalized Hat Problems Hardin, Christopher S., Taylor, Alan D.  November 26, 2012
(抜粋)
P109
Bibliography
[HT08b] Christopher S. Hardin and Alan D. Taylor. A peculiar connection between the axiom of choice and predicting the future. American Mathematical Monthly, 115(2):91{96, February 2008.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.365.7027&rep=rep1&type=pdf
[HT09] Christopher S. Hardin and Alan D. Taylor. Limit-like predictability for discontinuous functions. Proceedings of the AMS, 137:3123{3128, 2009.
http://www.jointmathematicsmeetings.org/proc/2009-137-09/S0002-9939-09-09877-3/S0002-9939-09-09877-3.pdf
(引用終り)（注：PDFのURLは、私が付与した）

（[HT08b](2008)が下記１）項関連、[HT09]（2009）が下記２）項関連、[成書]（2012）が３）項関連で、時間順です。）

（注：[HT08b] は、https://xorshammer.com/2008/08/23/set-theory-and-weather-prediction/
SET THEORY AND WEATHER PREDICTION XOR’S HAMMER Some things in mathematical logic that I find interesting WRITTEN BY MKOCONNOR Blog at WordPress.com. AUGUST 23, 2008
で 引用されており、かれの”Here’s a puzzle”の元ネタと思われる。

つづく

http://rio2016.5ch.net/test/read.cgi/math/1510442940/479

480: 現代数学の系譜 雑談 古典ガロア理論も読む ◆e.a0E5TtKE  [sage] 2017/11/22(水) 19:17:55.55 ID:mEHYOxL2

>>479 つづき

１）
さて、まず、[HT08b] より
(抜粋)
P91
1. INTRODUCTION.
We often model systems that change over time as functions from the real numbers R (or a subinterval of R) into some set S of states, and it is often our goal to predict the behavior of these systems.
Generally, this requires rules governing their behavior, such as a set of differential equations or the assumption that the system (as a function) is analytic.
With no such assumptions, the system could be an arbitrary function, and the values of arbitrary functions are notoriously hard to predict.
After all, if someone proposed a strategy for predicting the values of an arbitrary function based on its past values, a reasonable response might be,
“That is impossible. Given any strategy for predicting the values of an arbitrary function, one could just define a function that diagonalizes against it: whatever the strategy predicts, define the function to be something else.”
This argument, however, makes an appeal to induction:
to diagonalize against the proposed strategy at a point t, we must have already defined our function for all s < t in order to determine what the strategy would predict at t.

In fact, the lack of well-orderedness in the reals can be exploited to produce a very counterintuitive result: there is a strategy for predicting the values of an arbitrary function, based on its previous values, that is almost always correct.
Specifically, given the values of a function on an interval (?∞, t), the strategy produces a guess for the values of the function on [t,∞), and at all but countably many t, there is an ε > 0 such that the prediction is valid on [t, t + ε).
Noting that any countable set of reals has measure 0, we can restate this informally: at almost every instant t, the strateg predicts some “ε-glimpse” of the future.

つづく

http://rio2016.5ch.net/test/read.cgi/math/1510442940/480

上下前次1-新書関写板覧索設栞歴

ｽﾚ情報赤ﾚｽ抽出画像ﾚｽ抽出歴の未読ｽﾚ

ぬこの手ぬこTOP 0.027s