More than a 0-point
Commentationes Mathematicae Universitatis Carolinae, Tome 47 (2006) no. 4, pp. 617-621
Voir la notice de l'article provenant de la source Czech Digital Mathematics Library
\font\tenscr = rsfs10 \font\sevenscr = rsfs7 \font\fivescr = rsfs5 \textfont14=\tenscr \scriptfont14=\sevenscr \scriptscriptfont14=\fivescr \def\scr{\fam14} We construct in ZFC an ultrafilter $\scr U \in \Bbb N^{\ast}$ such that for every one-to-one function $f : \Bbb N\rightarrow \Bbb N$ there exists $U\in \scr U$ with $f[U]$ in the summable ideal, i.e. the sum of reciprocals of its elements converges. This strengthens Gryzlov's result concerning the existence of $0$-points.
Classification :
54D40, 54G99
Keywords: ultrafilter; $0$-point; summable ideal; linked family
Keywords: ultrafilter; $0$-point; summable ideal; linked family
@article{CMUC_2006__47_4_a6,
author = {Fla\v{s}kov\'a, Jana},
title = {More than a 0-point},
journal = {Commentationes Mathematicae Universitatis Carolinae},
pages = {617--621},
publisher = {mathdoc},
volume = {47},
number = {4},
year = {2006},
mrnumber = {2337416},
zbl = {1150.54025},
language = {en},
url = {http://geodesic.mathdoc.fr/item/CMUC_2006__47_4_a6/}
}
Flašková, Jana. More than a 0-point. Commentationes Mathematicae Universitatis Carolinae, Tome 47 (2006) no. 4, pp. 617-621. http://geodesic.mathdoc.fr/item/CMUC_2006__47_4_a6/