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Theorem stabnot 845

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 643	. . 3
2	1	biimpi 120	. 2
3		df-stab 843	. 2 STAB
4	2, 3	mpbir 146	1 STAB

Colors of variables: wff set class

This proof depends on syntax axioms:

wn 3

wi 4 STAB wstab 842

This proof depends on axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 623 ax-in2 624

This proof depends on definitions: df-bi 117 df-stab 843

This theorem is used by: dcnn 860 cnstab 8973