Cardinal invariants related to permutation groups
نویسندگان
چکیده
We consider the possible cardinalities of the following three cardinal invariants which are related to the permutation group on the set of natural numbers: ag := the least cardinal number of maximal cofinitary permutation groups; ap := the least cardinal number of maximal almost disjoint permutation families; c(Sym(N)) := the cofinality of the permutation group on the set of natural numbers. We show that it is consistent with ZFC that ap = ag < c(Sym(N)) = א2; in fact we show that in the Miller model ap = ag = א1 < א2 = c(Sym(N)).
منابع مشابه
Infinite Bounded Permutation Groups
This work concerns permutation groups on uncountable sets. The environment is ZFC, Set Theory with Axiom of Choice. Therefore the cardinal numbers are wellordered, a cardinal number k is infinite if and only if Ko < k, and each cardinal number k has a unique successor k. Throughout the paper Cl will be a set (usually infinite), n its cardinality, and m a cardinal number less than n. The support...
متن کاملCARDINAL INVARIANTS bκ AND tκ
This paper studies cardinal invariants bκ and tκ, the natural generalizations of the invariants b and t to a regular cardinal κ.
متن کاملCardinal invariants of ultraproducts of Boolean algebras
We deal with some of problems posed by Monk [Mo 1], [Mo 3] and related to cardinal invariant of ultraproducts of Boolean algebras. We also introduce and investigate several new cardinal invariants. AMS 1991 Mathematics Subject Classification primary: 03G05, 03E05, secondary: 06E15, 03E35 ∗ The research was partially supported by DFG grant Ko 490/7-1. This is publication number 534 of the second...
متن کاملCardinal coefficients associated to certain orders on ideals
We study cardinal invariants connected to certain classical orderings on the family of ideals on ω. We give topological and analytic characterizations of these invariants using the idealized version of Fréchet-Urysohn property and, in a special case, using sequential properties of the space of finitely-supported probability measures with the weak∗ topology. We investigate consistency of some in...
متن کاملSuborbits in Infinite Primitive Permutation Groups
For every infinite cardinal κ, we construct a primitive permutation group which has a finite suborbit paired with a suborbit of size κ. This answers a question of Peter M. Neumann.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Ann. Pure Appl. Logic
دوره 143 شماره
صفحات -
تاریخ انتشار 2006