There are absolute ultrafilters on N which are not minimal
نویسندگان
چکیده
منابع مشابه
P30: Are There Anxious Genes?
Anxiety comprises many clinical descriptions and phenotypes. A genetic predisposition to anxiety is undoubted; however, the nature and extent of that contribution is still unclear. Extensive genetic studies of the serotonin (5-hydroxytryptamine, 5-HT) transporter (5-HTT) gene have revealed how variation in gene expression can be correlated with anxiety phenotypes. Complete genome-wide linkage s...
متن کاملSemigroups in which all strongly summable ultrafilters are sparse
We show that if (S,+) is a commutative semigroup which can be embedded in the circle group T, in particular if S = (N,+), then all nonprincipal, strongly summable ultrafilters on S are sparse and can be written as sums in βS only trivially. We develop a simple condition on a strongly summable ultrafilter which guarantees that it is sparse and show that this holds for many ultrafilters on semigr...
متن کاملAre There More Than Minimal A Priori Constraints on Irrationality?
Our concern in this paper is with the question of how irrational an intentional agent can be, and, in particular, with an argument Stephen Stich has given for the claim that there are only very minimal a priori requirements on the rationality of intentional agents. The argument appears in chapter 2 of The Fragmentation of Reason. 1 Stich is concerned there with the prospects for the 'reform-min...
متن کاملA Model in Which There Are Jech–kunen Trees but There Are No Kurepa Trees
By an ω1–tree we mean a tree of power ω1 and height ω1. We call an ω1–tree a Jech–Kunen tree if it has κ–many branches for some κ strictly between ω1 and 21 . In this paper we construct the models of CH plus 21 > ω2, in which there are Jech–Kunen trees and there are no Kurepa trees. An partially ordered set, or poset for short, 〈T,<T 〉 is called a tree if for every t ∈ T the set {s ∈ T : s <T t...
متن کاملWhich elements of a finite group are non-vanishing?
Let $G$ be a finite group. An element $gin G$ is called non-vanishing, if for every irreducible complex character $chi$ of $G$, $chi(g)neq 0$. The bi-Cayley graph ${rm BCay}(G,T)$ of $G$ with respect to a subset $Tsubseteq G$, is an undirected graph with vertex set $Gtimes{1,2}$ and edge set ${{(x,1),(tx,2)}mid xin G, tin T}$. Let ${rm nv}(G)$ be the set of all non-vanishi...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Colloquium Mathematicum
سال: 1977
ISSN: 0010-1354,1730-6302
DOI: 10.4064/cm-37-1-29-34