4exmidOLD - Metamath Proof Explorer

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Theorem 4exmidOLD 998

Description: Obsolete proof of 4exmid 997 as of 29-Oct-2021. (Contributed by David Abernethy, 28-Jan-2014.) (New usage is discouraged.) (Proof modification is discouraged.)

**Assertion**
Ref	Expression
4exmidOLD	$/\$ $\/$ $/\$ $\/$ $/\$ $\/$ $/\$

**Proof of Theorem 4exmidOLD**
Step	Hyp	Ref	Expression
1		exmid 431	. 2 $\/$
2		dfbi3 994	. . 3 $/\$ $\/$ $/\$
3		xor 935	. . 3 $/\$ $\/$ $/\$
4	2, 3	orbi12i 543	. 2 $\/$ $/\$ $\/$ $/\$ $\/$ $/\$ $\/$ $/\$
5	1, 4	mpbi 220	1 $/\$ $\/$ $/\$ $\/$ $/\$ $\/$ $/\$

Colors of variables: wff setvar class

Syntax hints:

wn 3

wb 196 $\/$ wo 383 $/\$ wa 384

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8

This theorem depends on definitions: df-bi 197 df-or 385 df-an 386

This theorem is referenced by: (None)

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