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Mirrors > Home > ILE Home > Th. List > oridm | Unicode version |
Description: Idempotent law for disjunction. Theorem *4.25 of [WhiteheadRussell] p. 117. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Andrew Salmon, 16-Apr-2011.) (Proof shortened by Wolf Lammen, 10-Mar-2013.) |
Ref | Expression |
---|---|
oridm |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | pm1.2 673 | . 2 | |
2 | pm2.07 656 | . 2 | |
3 | 1, 2 | impbii 117 | 1 |
Colors of variables: wff set class |
Syntax hints: wb 98 wo 629 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 99 ax-ia2 100 ax-ia3 101 ax-io 630 |
This theorem depends on definitions: df-bi 110 |
This theorem is referenced by: pm4.25 675 orordi 690 orordir 691 truortru 1296 falorfal 1299 truxortru 1310 falxorfal 1313 unidm 3086 preqsn 3546 reapirr 7568 reapti 7570 lt2msq 7852 nn0ge2m1nn 8242 absext 9661 |
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