- {\displaystyle X\setminus A}
belongs to the
ultrafilter.
Ultrafilters on sets are an
important special instance of
ultrafilters on
partially ordered sets, where...
- and
ultrafilters on P ( X ) {\displaystyle {\mathcal {P}}(X)} are
usually called ultrafilters on the set X {\displaystyle X} . An
ultrafilter on a set...
- the set of all
ultrafilters on X , {\displaystyle X,} with the
elements of X {\displaystyle X}
corresponding to the prin****l
ultrafilters. The topology...
-
equal almost everywhere as
defined by an
ultrafilter. The
definition of
almost everywhere in
terms of
ultrafilters is
closely related to the
definition in...
- a κ {\displaystyle \kappa } -complete
ultrafilter. (W. W. Comfort, S. Negrepontis, The
Theory of
Ultrafilters, p.185) κ {\displaystyle \kappa } has Alexander's...
-
ultrafilter lemma implies that non-prin****l
ultrafilters exist on
every infinite set (these are
called free
ultrafilters).
Every net
valued in a
singleton subset...
- sets that
matter is
given by any free
ultrafilter U on the
natural numbers;
these can be
characterized as
ultrafilters that do not
contain any
finite sets...
-
proving that
certain perfect sets are uncountable, and the
construction of
ultrafilters. Let X {\textstyle X} be a set and A {\textstyle {\mathcal {A}}} a nonempty...
-
nonregular ultrafilters over very
small cardinals (related to the
famous Guilmann–Keisler
problem concerning existence of
nonregular ultrafilters), even with...
- S(B)} as follows: the
elements of S ( B ) {\displaystyle S(B)} are the
ultrafilters on B , {\displaystyle B,} and the
topology on S ( B ) , {\displaystyle...
