Implications

This non-implication, Form 5 \( \not \Rightarrow \) Form 31, whose code is 4, is constructed around a proven non-implication as follows:

  • An (optional) implication of code 1 or code 2 is given. In this case, it's Code 2: 10072, whose string of implications is:
    32 \(\Rightarrow\) 5
  • A proven non-implication whose code is 3. In this case, it's Code 3: 111, Form 32 \( \not \Rightarrow \) Form 31 whose summary information is:
    Hypothesis Statement
    Form 32 <p> \(C(\aleph_0,\le\aleph_0)\): Every denumerable set of non-empty countable sets  has a choice function. </p>

    Conclusion Statement
    Form 31 <p>\(UT(\aleph_{0},\aleph_{0},\aleph_{0})\): <strong>The countable union theorem:</strong>  The union of a denumerable set of denumerable sets is denumerable. </p>

  • This non-implication was constructed without the use of this last code 2/1 implication

The conclusion Form 5 \( \not \Rightarrow \) Form 31 then follows.

Finally, the
List of models where hypothesis is true and the conclusion is false:

Name Statement
\(\cal M12(\aleph)\) Truss' Model I This is a variation of Solovay's model, <a href="/models/Solovay-1">\(\cal M5(\aleph)\)</a> in which \(\aleph\) is singular
\(\cal M20\) Felgner's Model I Let \(\cal M\) be a model of \(ZF + V = L\). Felgner defines forcing conditions that force \(\aleph_{\omega}\) in \(\cal M\) to be \(\aleph_1\)
\(\cal N18\) Howard's Model I Let \(B= {B_n: n\in\omega}\) where the \(B_n\)'sare pairwise disjoint and each is countably infinite and let \(A=\bigcup B\)

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