Free sets for nowhere-dense set mappings

1981 ◽  
Vol 39 (1-2) ◽  
pp. 167-176 ◽  
Author(s):  
Uri Avraham
Order ◽  
1990 ◽  
Vol 7 (2) ◽  
pp. 179-182
Author(s):  
Kandasamy Muthuvel

1952 ◽  
Vol 4 ◽  
pp. 424-435 ◽  
Author(s):  
I. E. Glover

V. V. Golubev, in his study [6], has constructed, by using definite integrals, various examples of analytic functions having a perfect nowhere-dense set of singular points. These functions were shown to be single-valued with a bounded imaginary part. In attempting to extend his work to the problem of constructing analytic functions having perfect, nowhere-dense singular sets under quite general conditions, he posed the following question: Given an arbitrary, perfect, nowhere-dense point-set E of positive measure in the complex plane, is it possible to construct, by passing a Jordan curve through E and by using definite integrals, an example of a single-valued analytic function, which has E as its singular set, with its imaginary part bounded.


2000 ◽  
Vol 65 (1) ◽  
pp. 333-338 ◽  
Author(s):  
Péter Komjáth ◽  
Saharon Shelah

AbstractIt is consistent that there is a set mapping from the four-tuples of ωn into the finite subsets with no free subsets of size tn for some natural number tn. For any n < ω it is consistent that there is a set mapping from the pairs of ωn into the finite subsets with no infinite free sets. For any n < ω it is consistent that there is a set mapping from the pairs of ωn into ωn with no uncountable free sets.


1986 ◽  
Vol 51 (4) ◽  
pp. 1056-1060 ◽  
Author(s):  
Dan Velleman

In their paper [3], Hajnal and Komjáth define the following combinatorial principle:Definition 1.1. Suppose κ is an infinite cardinal and n < ω. Then Hn(κ) is the statement: There is a function F: [κ]n → [[κ]ω]≤ω such that(a) ∀A ∈[κ]n ∀Y ∈ F(A)(Y ⊆ min (A)), and(b) .Hn(κ) is related to a more general principle introduced by Hajnal and Nagy in [4]. For applications of these principles to free sets for set mappings and Ramsey games we refer the reader to [3] and [4].In [3] Hajnal and Komjáth prove the consistency of ZFC + GCH + ∀n ∈ ω(Hn + 1(ωn + 1)), relative to an ω-Mahlo cardinal. They conjecture that L is a model of this theory, and suggest that the proof might require higher gap morasses. The first few cases of this conjecture are known to be true; it is easy to see that if CH holds then H1 (ω1) is true, and Laver proved that V = L implies H2(ω2). In this paper we go one step further and prove V = L → H3(ω3). Unfortunately our methods do not appear to give Hn (ωn) for n ≥ 4.Most of our notation is standard. If X is any set and κ is a cardinal number then [X]κ is the set of subsets of X with cardinality κ, and [X]≤κ is the set of subsets of X with cardinality ≤ κ. If X is a set of ordinals then tp(X) is the order type of X.


2019 ◽  
Vol 12 (03) ◽  
pp. 1950040 ◽  
Author(s):  
Aliasghar Alikhani-Koopaei

In this paper, we present some results on typical properties of the sets of fixed points of bounded Baire one functions. In particular, we show that typical elements of a uniformly closed subclass [Formula: see text] of such class of functions have nowhere dense set of fixed points. We also show that typical elements of the class of bounded Baire one functions have [Formula: see text], where [Formula: see text] is an arbitrary continuous Borel measure on the unit interval.


2017 ◽  
Vol 63 (6) ◽  
pp. 605-613
Author(s):  
Antonio Avilés ◽  
Claribet Piña
Keyword(s):  

1953 ◽  
Vol 60 (6) ◽  
pp. 411
Author(s):  
Albert Wilansky
Keyword(s):  

2008 ◽  
Vol 155 (11) ◽  
pp. 1221-1226 ◽  
Author(s):  
Tadeusz Dobrowolski ◽  
Witold Marciszewski

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