pm2.13 - New Foundations Explorer

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Theorem pm2.13 407

Description: Theorem *2.13 of [WhiteheadRussell] p. 101. (Contributed by NM, 3-Jan-2005.)

**Assertion**
Ref	Expression
pm2.13	$\/$

**Proof of Theorem pm2.13**
Step	Hyp	Ref	Expression
1		notnot1 114	. 2
2	1	orri 365	1 $\/$

Colors of variables: wff setvar class

This proof depends on syntax axioms:

wn 3 $\/$ wo 357

This proof depends on axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8

This proof depends on definitions: df-bi 177 df-or 359

This theorem is used by: (None)