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Theorem ninba 972

Description: Miscellaneous inference relating falsehoods. (Contributed by NM, 31-Mar-1994.)

**Hypothesis**
Ref	Expression
ninba.1

**Assertion**
Ref	Expression
ninba	$/\$

**Proof of Theorem ninba**
Step	Hyp	Ref	Expression
1		ninba.1	. . 3
2	1	niabn 967	. 2 $/\$
3	2	bicomd 141	1 $/\$

Colors of variables: wff set class

Syntax hints:

wn 3

wi 4 $/\$ wa 104

wb 105

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 614 ax-in2 615

This theorem depends on definitions: df-bi 117

This theorem is referenced by: (None)