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Apr 17, 2019 at 3:15 review Close votes
Apr 17, 2019 at 13:27
Mar 21, 2019 at 13:10 review Close votes
Mar 21, 2019 at 17:02
Mar 18, 2019 at 23:28 answer added Andreas Lietz timeline score: 2
Mar 18, 2019 at 13:28 comment added Michael Greinecker It is not $2^{\omega\times\omega}$. Indeed, $\{(m,n)\mid m\leq n\}\notin\mathcal{U}$. For if $A\times B\subseteq \{(m,n)\mid m\leq n\}$, then $A$ must be finite and therefore $\mu^2(A\times B)=0$. A similar argument applies to the complement $\{(m,n)\mid m> n\}$.
Mar 18, 2019 at 11:35 history asked ar.grig CC BY-SA 4.0