nnexmid - Intuitionistic Logic Explorer

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Theorem nnexmid 840

Description: Double negation of decidability of a formula. See also comment of nndc 841 to avoid a pitfall that could come from the label "nnexmid". This theorem can also be proved from bj-nnor 13615 as in bj-nndcALT 13639. (Contributed by BJ, 9-Oct-2019.)

**Assertion**
Ref	Expression
nnexmid	$\/$

**Proof of Theorem nnexmid**
Step	Hyp	Ref	Expression
1		pm3.24 683	. 2 $/\$
2		ioran 742	. 2 $\/$ $/\$
3	1, 2	mtbir 661	1 $\/$

Colors of variables: wff set class

Syntax hints:

wn 3 $/\$ wa 103 $\/$ wo 698

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 ax-io 699

This theorem depends on definitions: df-bi 116

This theorem is referenced by: nndc 841 exmid1stab 13880

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