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Metamath Proof Explorer

Definition df-base

Description: Define the base set (also called underlying set, ground set, carrier set, or carrier) extractor for extensible structures. (Contributed by NM, 4-Sep-2011) (Revised by Mario Carneiro, 14-Aug-2015) Use its index-independent form baseid instead. (New usage is discouraged.)

		Ref	Expression
	Assertion	df-base	$⊢ Base = Slot 1$

Detailed syntax breakdown

Step	Hyp	Ref	Expression
0		cbs	$class Base$
1		c1	$class 1$
2	1	cslot	$class Slot 1$
3	0 2	wceq	$wff Base = Slot 1$