New posts in ordinals

Non-existence of a surjection $\aleph_n \to \aleph_{n+1}$, without the axiom of choice

set-theory cardinals axiom-of-choice ordinals

$\varepsilon$-number countability without choice

set-theory axiom-of-choice ordinals

Linearly ordered sets "somewhat similar" to $\mathbb{Q}$

set-theory order-theory ordinals

Are these two parametric versions of Transfinite Recursion equivalent?

set-theory ordinals transfinite-recursion

How many epsilon numbers $<\omega_1$ are there?

set-theory ordinals

How many ordinals can we cram into $\mathbb{R}_+$, respecting order?

order-theory ordinals

How to show countability of $\omega^\omega$ or $\epsilon_0$ in ZF?

set-theory axiom-of-choice ordinals

Can we describe any subsets of $\mathbb{N}$ occurring in a late layer of the Constructible Universe?

logic set-theory computability ordinals descriptive-set-theory

Ordinal exponentiation - $2^{\omega}=\omega$

set-theory order-theory ordinals

Hessenberg power of ordinals

set-theory order-theory ordinals well-orders

Benefits Of Using SQL Ordinal Position Notation?

sql sql-server oracle ordinals

Do there exist totally ordered sets with the 'distinct order type' property that are not well-ordered?

order-theory ordinals

Infinite combinatorial games

set-theory ordinals infinitary-combinatorics infinite-games

Best known upper and lower bounds for $\omega_1$

set-theory cardinals ordinals

Surcomplex numbers and the largest algebraically closed field

field-theory ordinals surreal-numbers

Prove that no ordinal is an element of itself

set-theory ordinals well-orders

Prove that $\forall\alpha\geq\omega$, $|L_\alpha|=|\alpha|$ without AC

logic set-theory cardinals axiom-of-choice ordinals

Commutativity of Ordinal Multiplication

set-theory ordinals

Can any infinite ordinal be expressed as the sum of a limit ordinal and a finite ordinal?

set-theory ordinals

How to identify limit ordinals?

set-theory ordinals