huge cardinal
In mathematics, a cardinal number is called huge if there exists an elementary embedding from into a transitive inner model with critical point and
:
Here, is the class of all sequences of length whose elements are in .
Huge cardinals were introduced by {{harvs|txt|authorlink=Kenneth Kunen|first=Kenneth |last=Kunen|year=1978}}.
Variants
In what follows, refers to the -th iterate of the elementary embedding , that is, composed with itself times, for a finite ordinal . Also, is the class of all sequences of length less than whose elements are in . Notice that for the "super" versions, should be less than , not .
κ is almost n-huge if and only if there is with critical point and
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κ is super almost n-huge if and only if for every ordinal γ there is with critical point , , and
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κ is n-huge if and only if there is with critical point and
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κ is super n-huge if and only if for every ordinal there is with critical point , , and
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Notice that 0-huge is the same as measurable cardinal; and 1-huge is the same as huge. A cardinal satisfying one of the rank into rank axioms is -huge for all finite .
The existence of an almost huge cardinal implies that Vopěnka's principle is consistent; more precisely any almost huge cardinal is also a Vopěnka cardinal.
Kanamori, Reinhardt, and Solovay defined seven large cardinal properties between extendibility and hugeness in strength, named through , and a property .A. Kanamori, W. N. Reinhardt, R. Solovay, "[https://math.bu.edu/people/aki/d.pdf Strong Axioms of Infinity and Elementary Embeddings]", pp.110--111. Annals of Mathematical Logic vol. 13 (1978). The additional property is equivalent to " is huge", and is equivalent to " is -supercompact for all
Consistency strength
The cardinals are arranged in order of increasing consistency strength as follows:
- almost
n -huge - super almost
n -huge n -huge- super
n -huge - almost
n+1 -huge
The consistency of a huge cardinal implies the consistency of a supercompact cardinal, nevertheless, the least huge cardinal is smaller than the least supercompact cardinal (assuming both exist).
ω-huge cardinals
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One can try defining an
See also
- List of large cardinal properties
- The Dehornoy order on a braid group was motivated by properties of huge cardinals.
References
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- {{Citation|last=Kanamori|first=Akihiro|authorlink=Akihiro Kanamori|year=2003|publisher=Springer|title=The Higher Infinite : Large Cardinals in Set Theory from Their Beginnings|title-link= The Higher Infinite |edition=2nd|isbn=3-540-00384-3}}.
- {{Citation | last=Kunen | first=Kenneth | authorlink=Kenneth Kunen | title=Saturated ideals | doi=10.2307/2271949 | jstor=2271949 | mr=495118 | year=1978 | journal=The Journal of Symbolic Logic | issn=0022-4812 | volume=43 | issue=1 | pages=65–76| s2cid=13379542 }}.
- {{Citation|last=Maddy|first=Penelope|authorlink=Penelope Maddy|journal=The Journal of Symbolic Logic|title=Believing the Axioms. II|year=1988|volume=53|issue=3|pages=736-764 (esp. 754-756)|doi=10.2307/2274569|jstor=2274569|s2cid=16544090 }}. A copy of parts I and II of this article with corrections is available at the [http://faculty.sites.uci.edu/pjmaddy/bibliography/ author's web page].
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