Implications

This non-implication, Form 280 \( \not \Rightarrow \) Form 216, whose code is 6, is constructed around a proven non-implication as follows:
Note: This non-implication is actually a code 4, as this non-implication satisfies the transferability criterion. Click Transfer details for all the details)

  • An (optional) implication of code 1 or code 2 is given. In this case, it's Code 2: 5895, whose string of implications is:
    99 \(\Rightarrow\) 70 \(\Rightarrow\) 142 \(\Rightarrow\) 280
  • A proven non-implication whose code is 5. In this case, it's Code 3: 250, Form 99 \( \not \Rightarrow \) Form 216 whose summary information is:
    Hypothesis Statement
    Form 99 <p> <strong>Rado's Selection Lemma:</strong> Let \(\{K(\lambda): \lambda \in\Lambda\}\) be a family  of finite subsets (of \(X\)) and suppose for each finite \(S\subseteq\Lambda\) there is a function \(\gamma(S): S \rightarrow X\) such that \((\forall\lambda\in S)(\gamma(S)(\lambda)\in K(\lambda))\).  Then there is an \(f: \Lambda\rightarrow X\) such that for every finite \(S\subseteq\Lambda\) there is a finite \(T\) such that \(S\subseteq T\subseteq\Lambda\) and such that \(f\) and \(\gamma (T)\) agree on S. </p>

    Conclusion Statement
    Form 216 <p> Every infinite tree has either an infinite chain or an infinite antichain. </p>

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

The conclusion Form 280 \( \not \Rightarrow \) Form 216 then follows.

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

Name Statement
\(\cal N2\) The Second Fraenkel Model The set of atoms \(A=\{a_i : i\in\omega\}\) is partitioned into two element sets \(B =\{\{a_{2i},a_{2i+1}\} : i\in\omega\}\). \(\mathcal G \) is the group of all permutations of \( A \) that leave \( B \) pointwise fixed and \( S \) is the set of all finite subsets of \( A \).

Edit | Back