New posts in ordinals

Why do we classify infinities in so many symbols and ideas?

cardinals infinity ordinals

Countable ordinals are embeddable in the rationals $\Bbb Q$ -- proofs and their use of AC

set-theory order-theory axiom-of-choice ordinals

Which set is unwell-orderable?

elementary-set-theory cardinals axiom-of-choice ordinals

The cardinality of a countable union of countable sets, without the axiom of choice

set-theory cardinals axiom-of-choice ordinals

A transfinite epistemic logic puzzle: what numbers did Cheryl give to Albert and Bernard?

logic ordinals

Godel's pairing function and proving c = c*c for aleph cardinals

set-theory cardinals ordinals

Do $\omega^\omega=2^{\aleph_0}=\aleph_1$?

set-theory cardinals ordinals

What does order topology over Ordinal numbers look like, and how does it work?

general-topology ordinals order-topology

Prove: If $A$ and $B$ are closed subsets of $[0,\Omega]$ then at least $A$ or $B$ is bounded

general-topology proof-writing proof-explanation ordinals order-topology

Is Zorn's lemma applicable to this integration problem?

measure-theory lebesgue-integral ordinals

Embedding ordinals in $\mathbb{Q}$

order-theory ordinals

Construction of a model of ZF with a discontinuous but sequentially continuous function.

real-analysis set-theory ordinals

Closed Intervals of $\omega_1$ Are Compact

general-topology set-theory compactness ordinals order-topology