We have the following indirect implication of form equivalence classes:
Implication | Reference |
---|---|
399 \(\Rightarrow\) 323 | clear |
323 \(\Rightarrow\) 62 | note-70 |
62 \(\Rightarrow\) 61 | clear |
61 \(\Rightarrow\) 88 | clear |
88 \(\Rightarrow\) 268 |
Subalgebra lattices of unary algebras and an axiom of choice, Lampe, W. A. 1974, Colloq. Math. |
Here are the links and statements of the form equivalence classes referenced above:
Howard-Rubin Number | Statement |
---|---|
399: | \(KW(\infty,LO)\), The Kinna-Wagner Selection Principle for a set of linearly orderable sets: For every set of linearly orderable sets \(M\) there is a function \(f\) such that for all \(A\in M\), if \(|A|>1\) then \(\emptyset\neq f(A)\subsetneq A\). |
323: | \(KW(\infty,WO)\), The Kinna-Wagner Selection Principle for a family of well orderable sets: For every set \(M\) of well orderable sets there is a function \(f\) such that for all \(A\in M\), if \(|A| > 1\) then \(\emptyset\neq f(A)\subsetneq A\). (See Form 15.) |
62: | \(C(\infty,< \aleph_{0})\): Every set of non-empty finite sets has a choice function. |
61: | \((\forall n\in\omega, n\ge 2\))\((C(\infty,n))\): For each \(n\in\omega\), \(n\ge 2\), every set of \(n\) element sets has a choice function. |
88: | \(C(\infty ,2)\): Every family of pairs has a choice function. |
268: | If \({\cal L}\) is a lattice isomorphic to the lattice of subalgebras of some unary universal algebra (a unary universal algebra is one with only unary or nullary operations) and \(\alpha \) is an automorphism of \({\cal L}\) of order 2 (that is, \(\alpha ^{2}\) is the identity) then there is a unary algebra \(\frak A\) and an isomorphism \(\rho \) from \({\cal L}\) onto the lattice of subalgebras of \(\frak A^{2}\) with \[\rho(\alpha(x))=(\rho(x))^{-1} (= \{(s,t) : (t,s)\in\rho(x)\})\] for all \(x\in {\cal L}\). |
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