dcnnOLD - Intuitionistic Logic Explorer

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Theorem dcnnOLD 839

Description: Obsolete proof of dcnnOLD 839 as of 25-Nov-2023. (Contributed by David A. Wheeler, 6-Dec-2018.) (Proof modification is discouraged.) (New usage is discouraged.)

**Assertion**
Ref	Expression
dcnnOLD	DECID DECID

**Proof of Theorem dcnnOLD**
Step	Hyp	Ref	Expression
1		notnotnot 624	. . . 4
2	1	orbi2i 752	. . 3 $\/$ $\/$
3		orcom 718	. . 3 $\/$ $\/$
4	2, 3	bitri 183	. 2 $\/$ $\/$
5		df-dc 825	. 2 DECID $\/$
6		df-dc 825	. 2 DECID $\/$
7	4, 5, 6	3bitr4ri 212	1 DECID DECID

Colors of variables: wff set class

Syntax hints:

wn 3

wb 104 $\/$ wo 698 DECID wdc 824

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 df-dc 825

This theorem is referenced by: (None)

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