32 citations · 206 across the 50 of their papers we have counts for
23 papers · 1 filter
The Rearrangement Number
Andreas Blass, Jörg Brendle, Will Brian +3
How many permutations of the natural numbers are needed so that every conditionally convergent series of real numbers can be rearranged to no longer converge to the same sum? We de…
Partitions and conservativity
Andreas Blass
We study the partition properties enjoyed by the "next best thing to a P-point'' ultrafilters introduced recently in joint work with Dobrinen and Raghavan. That work established so…
Finite Embeddability of Sets and Ultrafilters
Andreas Blass, Mauro Di Nasso
A set A of natural numbers is finitely embeddable in another such set B if every finite subset of A has a rightward translate that is a subset of B. This notion of finite embeddabi…
The next best thing to a P-point
Andreas Blass, Natasha Dobrinen, Dilip Raghavan
We study ultrafilters on produced by forcing with the quotient of $\scr P(ω^2)$ by the Fubini square of the Fréchet filter on . We show that such an ultrafilter is a weak…
Quasi-selective ultrafilters and asymptotic numerosities
Andreas Blass, Mauro Di Nasso, Marco Forti
We isolate a new class of ultrafilters on N, called "quasi-selective" because they are intermediate between selective ultrafilters and P-points. (Under the Continuum Hypothesis the…
Generalizing Hartogs' Trichotomy Theorem
David Feldman, Mehmet Orhon, Andreas Blass
A celebrated argument of F. Hartogs (1915) deduces the Axiom of Choice from the hypothesis of comparability for any pair of cardinals. We show how each of a sequence of seemingly m…