翻訳と辞書
Words near each other
・ "O" Is for Outlaw
・ "O"-Jung.Ban.Hap.
・ "Ode-to-Napoleon" hexachord
・ "Oh Yeah!" Live
・ "Our Contemporary" regional art exhibition (Leningrad, 1975)
・ "P" Is for Peril
・ "Pimpernel" Smith
・ "Polish death camp" controversy
・ "Pro knigi" ("About books")
・ "Prosopa" Greek Television Awards
・ "Pussy Cats" Starring the Walkmen
・ "Q" Is for Quarry
・ "R" Is for Ricochet
・ "R" The King (2016 film)
・ "Rags" Ragland
・ ! (album)
・ ! (disambiguation)
・ !!
・ !!!
・ !!! (album)
・ !!Destroy-Oh-Boy!!
・ !Action Pact!
・ !Arriba! La Pachanga
・ !Hero
・ !Hero (album)
・ !Kung language
・ !Oka Tokat
・ !PAUS3
・ !T.O.O.H.!
・ !Women Art Revolution


Dictionary Lists
翻訳と辞書 辞書検索 [ 開発暫定版 ]
スポンサード リンク

prewellordering : ウィキペディア英語版
prewellordering
In set theory, a prewellordering is a binary relation \le that is transitive, total, and wellfounded (more precisely, the relation x\le y\land y\nleq x is wellfounded). In other words, if \leq is a prewellordering on a set X, and if we define \sim by
:x\sim y\iff x\leq y \land y\leq x
then \sim is an equivalence relation on X, and \leq induces a wellordering on the quotient X/\sim. The order-type of this induced wellordering is an ordinal, referred to as the length of the prewellordering.
A norm on a set X is a map from X into the ordinals. Every norm induces a prewellordering; if \phi:X\to Ord is a norm, the associated prewellordering is given by
:x\leq y\iff\phi(x)\leq\phi(y)
Conversely, every prewellordering is induced by a unique regular norm (a norm \phi:X\to Ord is regular if, for any x\in X and any \alpha<\phi(x), there is y\in X such that \phi(y)=\alpha).
== Prewellordering property ==
If \boldsymbol is a pointclass of subsets of some collection \mathcal of Polish spaces, \mathcal closed under Cartesian product, and if \leq is a prewellordering of some subset P of some element X of \mathcal, then \leq is said to be a \boldsymbol-prewellordering of P if the relations <^
*\, and \leq^
* are elements of \boldsymbol, where for x,y\in X,
# x<^
*y\iff x\in P\land(P\lor\ )
# x\leq^
* y\iff x\in P\land(P\lor x\leq y )
\boldsymbol is said to have the prewellordering property if every set in \boldsymbol admits a \boldsymbol-prewellordering.
The prewellordering property is related to the stronger scale property; in practice, many pointclasses having the prewellordering property also have the scale property, which allows drawing stronger conclusions.

抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)
ウィキペディアで「prewellordering」の詳細全文を読む



スポンサード リンク
翻訳と辞書 : 翻訳のためのインターネットリソース

Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.