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Metamath Proof Explorer

Definition df-4

Description: Define the number 4. (Contributed by NM, 27-May-1999)

		Ref	Expression
	Assertion	df-4	$⊢ 4 = 3 + 1$

Step	Hyp	Ref	Expression
0		c4	$class 4$
1		c3	$class 3$
2		caddc	$class +$
3		c1	$class 1$
4	1 3 2	co	$class (3 + 1)$
5	0 4	wceq	$wff 4 = 3 + 1$