Metamath Proof Explorer


Theorem 2on

Description: Ordinal 2 is an ordinal number. (Contributed by NM, 18-Feb-2004) (Proof shortened by Andrew Salmon, 12-Aug-2011)

Ref Expression
Assertion 2on 2 𝑜 On

Proof

Step Hyp Ref Expression
1 df-2o 2 𝑜 = suc 1 𝑜
2 1on 1 𝑜 On
3 2 onsuci suc 1 𝑜 On
4 1 3 eqeltri 2 𝑜 On