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jaakov
Posts:
11
Registered:
12/3/12
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Re: Given a set , is there a disjoint set with an arbitrary cardinality?
Posted:
Dec 3, 2012 11:41 AM
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On 03.12.2012 17:33, Aatu Koskensilta wrote:
> jaakov<removeit_jaakov@deleteit_ro.ru> writes:
>
>> Thank you. To finish this proof, we have to prove that your class, let
>> us call it Z, contains an initial segment of cardinality k. However,
>> informally speaking, X may hypothetically contain too many ordinals,
>> still being a set, such that too few ordinals remain in Z. Could you
>> please expand on why Z contains an initial segment of cardinality k?
>
> Assuming choice, the cardinality k of X is an (initial) ordinal, so
> take the set X' = {alpha | alpha< k} and let Y be the set {x + lambda |
> x in X'}, where lambda is an ordinal> any ordinal in X.
>
1. k is not related to the cardinality of X.
2. Your lambda need not exist. To show that lambda exists, one has to
show that a set may not contain arbitrarily large ordinals. Is it a
known fact or simply false?
Jaakov.
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