New posts in ordinals

There is a well ordering of the class of all finite sequences of ordinals

elementary-set-theory ordinals well-orders

Ordinal tetration: The issue of ${}^{\epsilon_0}\omega$

ordinals tetration hyperoperation

Cardinal Arithmetic versus Ordinal Arithmetic

set-theory cardinals ordinals

Simple example of uncountable ordinal

set-theory cardinals ordinals

How do you find the smallest of homeomorphic ordinals?

general-topology ordinals descriptive-set-theory

Is it really impossible to lose the Hydra game?

graph-theory ordinals provability

Fundamental Group of the Long Line

general-topology ordinals fundamental-groups

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

set-theory order-theory ordinals

Is it possible to select sql server data using column ordinal position

sql sql-server sql-server-2005 tsql ordinals

Let $α$ be an ordinal and $A$ be a set of ordinals. Then $\sup\limits_{β∈A} (α+β) = α+\sup\limits_{β∈A}(β)$

proof-explanation ordinals

Prove that $\omega + \omega_1 = \omega \cdot \omega_1 = \omega^{\omega_1} = \omega_1$

set-theory ordinals

Where is the theorem related to the construction of countable admissible ordinals by Turing machines with oracles?

logic reference-request ordinals turing-machines oracles

Is a limit ordinal necessarily a cardinal?

elementary-set-theory cardinals ordinals

Can we treat proper classes in a well-defined way that has them behave as ordinal numbers?

set-theory cardinals ordinals surreal-numbers

How to think about ordinal exponentiation?

set-theory ordinals

Why study cardinals, ordinals and the like?

elementary-set-theory cardinals ordinals motivation

Is there an axiomatic approach to ordinal arithmetic?

reference-request ordinals axioms

How many positive numbers need to be added together to ensure that the sum is infinite?

sequences-and-series set-theory ordinals

Uncountability of countable ordinals

set-theory ordinals

When does ordinal addition/multiplication commute?

set-theory ordinals