Fraenkel \(\cal N32\): Hickman's Model III | Back to this models page
Description: This is a variation of \(\cal N1\)
When the book was first being written, only the following form classes were known to be true in this model:
Form Howard-Rubin Number | Statement |
---|---|
6 | \(UT(\aleph_0,\aleph_0,\aleph_0,\Bbb R)\): The union of a denumerable family of denumerable subsets of \({\Bbb R}\) is denumerable. |
37 | Lebesgue measure is countably additive. |
91 | \(PW\): The power set of a well ordered set can be well ordered. |
130 | \({\cal P}(\Bbb R)\) is well orderable. |
191 | \(SVC\): There is a set \(S\) such that for every set \(a\), there is an ordinal \(\alpha\) and a function from \(S\times\alpha\) onto \(a\). |
273 | There is a subset of \({\Bbb R}\) which is not Borel. |
305 | There are \(2^{\aleph_0}\) Vitali equivalence classes. (Vitali equivalence classes are equivalence classes of the real numbers under the relation \(x\equiv y\leftrightarrow(\exists q\in{\Bbb Q})(x-y=q)\).). \ac{Kanovei} \cite{1991}. |
309 | The Banach-Tarski Paradox: There are three finite partitions \(\{P_1,\ldots\), \(P_n\}\), \(\{Q_1,\ldots,Q_r\}\) and \(\{S_1,\ldots,S_n, T_1,\ldots,T_r\}\) of \(B^3 = \{x\in {\Bbb R}^3 : |x| \le 1\}\) such that \(P_i\) is congruent to \(S_i\) for \(1\le i\le n\) and \(Q_i\) is congruent to \(T_i\) for \(1\le i\le r\). |
313 | \(\Bbb Z\) (the set of integers under addition) is amenable. (\(G\) is {\it amenable} if there is a finitely additive measure \(\mu\) on \(\cal P(G)\) such that \(\mu(G) = 1\) and \(\forall A\subseteq G, \forall g\in G\), \(\mu(gA)=\mu(A)\).) |
361 | In \(\Bbb R\), the union of a denumerable number of analytic sets is analytic. G. Moore [1982], pp 181 and 325. |
363 | There are exactly \(2^{\aleph_0}\) Borel sets in \(\Bbb R\). G. Moore [1982], p 325. |
368 | The set of all denumerable subsets of \(\Bbb R\) has power \(2^{\aleph_0}\). |
369 | If \(\Bbb R\) is partitioned into two sets, at least one of them has cardinality \(2^{\aleph_0}\). |
When the book was first being written, only the following form classes were known to be false in this model:
Form Howard-Rubin Number | Statement |
---|---|
15 | \(KW(\infty,\infty)\) (KW), The Kinna-Wagner Selection Principle: For every set \(M\) there is a function \(f\) such that for all \(A\in M\), if \(|A|>1\) then \(\emptyset\neq f(A)\subsetneq A\). (See Form 81(\(n\)). |
192 | \(EP\) sets: For every set \(A\) there is a projective set \(X\) and a function from \(X\) onto \(A\). |
237 | The order of any group is divisible by the order of any of its subgroups, (i.e., if \(H\) is a subgroup of \(G\) then there is a set \(A\) such that \(|H\times A| = |G|\).) |
238 | Every elementary Abelian group (that is, for some prime \(p\) every non identity element has order \(p\)) is the direct sum of cyclic subgroups. |
240 | If a group \(G\) satisfies "every ascending chain of subgroups is finite", then every subgroup of \(G\) is finitely generated. |
Historical background: Let \(A\)be denumerable. Construct an elementary Abelean \(p\)-group \(G\) on \(A\) where\(p\) is a prime. (Every non-identity element has order \(p\).) Let \(\cal G\)be the group of automorphisms of \(G\), and let \(S\) be the set of finitesubsets of \(A\). Hickman proves that if \(H\) is any non-trivial subgroup of\(G\), then the order of \(H\) does not divide the order of \(G\) (237 isfalse). Thus, it follows that \(G\) is not the direct sum of cyclic groups(238 is false). Hickman also shows that in \(G\) every ascending chain ofsubgroups is finite, but \(G\) is not finitely generated (240 is false).
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