Inter-universal geometry と ABC予想 (応援スレ) 73

Inter-universal geometry と ABC予想 (応援スレ) 73 (766ﾚｽ)
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611: 現代数学の系譜 雑談 ◆yH25M02vWFhP  [] 2025/08/13(水) 16:30:57.41 ID:ZWqlQsZq

つづき

https://en.wikipedia.org/wiki/Well-order
Well-order
Reals
The standard ordering ≤ of any real interval is not a well ordering, since, for example, the open interval ⁠
(0,1)⊆[0,1]
⁠ does not contain a least element. From the ZFC axioms of set theory (including the axiom of choice) one can show that there is a well order of the reals. Also Wacław Sierpiński proved that ZF + GCH (the generalized continuum hypothesis) imply the axiom of choice and hence a well order of the reals. Nonetheless, it is possible to show that the ZFC+GCH axioms alone are not sufficient to prove the existence of a definable (by a formula) well order of the reals.[3] However it is consistent with ZFC that a definable well ordering of the reals exists—for example, it is consistent with ZFC that V=L, and it follows from ZFC+V=L that a particular formula well orders the reals, or indeed any set.

https://en.wikipedia.org/wiki/Zorn%27s_lemma
Zorn's lemma implies the axiom of choice
A proof that Zorn's lemma implies the axiom of choice illustrates a typical application of Zorn's lemma.[17] (The structure of the proof is exactly the same as the one for the Hahn–Banach theorem.)
略
ssentially the same proof also shows that Zorn's lemma implies the well-ordering theorem: take
P to be the set of all well-ordered subsets of a given set
X and then shows a maximal element of
P is X.[18]

https://ja.wikipedia.org/wiki/%E9%80%A3%E7%B6%9A%E4%BD%93%E4%BB%AE%E8%AA%AC
連続体仮説
歴史
1963年、ポール・コーエンは強制法と呼ばれる新しい手法を用いて「ZFC から連続体仮説を証明することは出来ない」ことを示した
コーエンはこの業績により、1966 年にフィールズ賞を受賞している
(引用終り)
以上

http://rio2016.5ch.net/test/read.cgi/math/1753000052/611

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