Implications

• Implications Home
• Complete List
• Search

This non-implication, Form 173 \( \not \Rightarrow \) Form 421, 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: 5912, whose string of implications is: 214 \(\Rightarrow\) 76 \(\Rightarrow\) 173
• A proven non-implication whose code is 3. In this case, it's Code 3: 877, Form 214 \( \not \Rightarrow \) Form 32 whose summary information is:
  

  Hypothesis	Statement
  Form 214	<p> \(Z(\omega)\): For every family \(A\) of infinite sets, there is a function \(f\) such that for all \(y\in A\), \(f(y)\) is a non-empty subset of \(y\) and \(|f(y)|=\aleph_{0}\). </p>

  
  

  Conclusion	Statement
  Form 32	<p> \(C(\aleph_0,\le\aleph_0)\): Every denumerable set of non-empty countable sets  has a choice function. </p>

  
  
• An (optional) implication of code 1 or code 2 is given. In this case, it's Code 2: 9345, whose string of implications is: 421 \(\Rightarrow\) 338 \(\Rightarrow\) 32

The conclusion Form 173 \( \not \Rightarrow \) Form 421 then follows.

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

Name	Statement
\(\cal M29\) Pincus' Model II	Pincus constructs a generic extension \(M[I]\) of a model \(M\) of \(ZF +\) class choice \(+ GCH\) in which \(I=\bigcup_{n\in\omega}I_n\), \(I_{-1}=2\) and \(I_{n+1}\) is a denumerable set of independent functions from \(\omega\) onto \(I_n\)