Definition df-altop 28123

Description: An alternative definition of ordered pairs. This definition removes a hypothesis from its defining theorem (see altopth 28134), making it more convenient in some circumstances. (Contributed by Scott Fenton, 22-Mar-2012.)

Assertion

Ref	Expression
df-altop	|- << A , B >> = { { A } , { A , { B } } }

Detailed syntax breakdown of Definition df-altop

Step	Hyp	Ref	Expression
1		cA	. . 3 class A
2		cB	. . 3 class B
3	1, 2	caltop 28121	. 2 class << A , B >>
4	1	csn 3975	. . 3 class { A }
5	2	csn 3975	. . . 4 class { B }
6	1, 5	cpr 3977	. . 3 class { A , { B } }
7	4, 6	cpr 3977	. 2 class { { A } , { A , { B } } }
8	3, 7	wceq 1370	1 wff << A , B >> = { { A } , { A , { B } } }

This definition is referenced by:  altopex  28125  altopthsn  28126  altxpsspw  28142  rankaltopb  28144  nfaltop  28145