New posts in ordinals

Products and coproducts in the simplex category

An easy to understand definition of $\omega_1$?

what does it mean that constructible universe is definable from ordinals?

What set theory axioms do I need to believe in uncountable ordinals?

If $\alpha$ is an indecomposable ordinal, why $\Gamma(\alpha\times{\alpha})=\alpha$?

Does every ordinal have cardinality no greater than $\aleph_\mathbb{0}$?

"If inaccessible sets exist, their existence is not provable in ZF"

Which ordinals can be "mistaken for" $\aleph_1$?

Is the proper class of all ordinals equivalent to the potential infinity of pre-Cantor times?

Ordinals - motivation and rigor at the same time

Simple (even toy) examples for uses of Ordinals?

How can I call a exported function using ordinal number

How to prove the Milner-Rado Paradox?

Definition of cofinality

Definable order types without infinity axiom.

Order-preserving injections of ordinals into $[0,1]$

Is $\pmb{\eta}\cdot\pmb{\omega_1} = (\pmb{\eta} + \pmb{1})\cdot\pmb{\omega_1}$?

Cofinality of an infinite cardinal, alternative definition

Curious facts about ordinal numbers

The Use of Ordinals and Cardinals in Recursive Proofs