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Theorem stabnot 823

Description: Every negated formula is stable. (Contributed by David A. Wheeler, 13-Aug-2018.)

**Assertion**
Ref	Expression
stabnot	STAB

**Proof of Theorem stabnot**
Step	Hyp	Ref	Expression
1		notnotnot 624	. . 3
2	1	biimpi 119	. 2
3		df-stab 821	. 2 STAB
4	2, 3	mpbir 145	1 STAB

Colors of variables: wff set class

Syntax hints:

wn 3

wi 4 STAB wstab 820

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 604 ax-in2 605

This theorem depends on definitions: df-bi 116 df-stab 821

This theorem is referenced by: dcnn 838 cnstab 8543