Theorem ornld 898

Description: Selecting one statement from a disjunction if one of the disjuncted statements is false. (Contributed by AV, 6-Sep-2018.) (Proof shortened by AV, 13-Oct-2018.) (Proof shortened by Wolf Lammen, 19-Jan-2020.)

Assertion

Ref	Expression
ornld

Proof of Theorem ornld

Step	Hyp	Ref	Expression
1		pm3.35 587	. . 3
2	1	ord 377	. 2
3	2	expimpd 603	1

Syntax hints:  -.wn 3  ->wi 4  \/wo 368  /\wa 369

This theorem is referenced by:  friendshipgt3  25121  ralralimp  32295

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 185  df-or 370  df-an 371