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Metamath Proof Explorer

Theorem df1o2

Description: Expanded value of the ordinal number 1. Definition 2.1 of Schloeder p. 4. (Contributed by NM, 4-Nov-2002)

		Ref	Expression
	Assertion	df1o2	$⊢ 1_{𝑜} = \{\emptyset\}$

Step	Hyp	Ref	Expression
1		df-1o	$⊢ 1_{𝑜} = suc \emptyset$
2		suc0	$⊢ suc \emptyset = \{\emptyset\}$
3	1 2	eqtri	$⊢ 1_{𝑜} = \{\emptyset\}$