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Theorem stabnot 774

Description: Every formula of the form

is stable. Uses notnotnot 660. (Contributed by David A. Wheeler, 13-Aug-2018.)

**Assertion**
Ref	Expression
stabnot	STAB

**Proof of Theorem stabnot**
Step	Hyp	Ref	Expression
1		notnotnot 660	. . 3
2	1	biimpi 118	. 2
3		df-stab 773	. 2 STAB
4	2, 3	mpbir 144	1 STAB

Colors of variables: wff set class

Syntax hints:

wn 3

wi 4 STAB wstab 772

This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-in1 576 ax-in2 577

This theorem depends on definitions: df-bi 115 df-stab 773

This theorem is referenced by: (None)