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Mirrors > Home > MPE Home > Th. List > oridm | Structured version Visualization version GIF version |
Description: Idempotent law for disjunction. Theorem *4.25 of [WhiteheadRussell] p. 117. (Contributed by NM, 11-May-1993.) (Proof shortened by Andrew Salmon, 16-Apr-2011.) (Proof shortened by Wolf Lammen, 10-Mar-2013.) |
Ref | Expression |
---|---|
oridm | ⊢ ((𝜑 ∨ 𝜑) ↔ 𝜑) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | pm1.2 534 | . 2 ⊢ ((𝜑 ∨ 𝜑) → 𝜑) | |
2 | pm2.07 410 | . 2 ⊢ (𝜑 → (𝜑 ∨ 𝜑)) | |
3 | 1, 2 | impbii 198 | 1 ⊢ ((𝜑 ∨ 𝜑) ↔ 𝜑) |
Colors of variables: wff setvar class |
Syntax hints: ↔ wb 195 ∨ wo 382 |
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 196 df-or 384 |
This theorem is referenced by: pm4.25 536 orordi 551 orordir 552 truortru 1501 falorfal 1504 unidm 3718 preqsnd 4330 preqsn 4331 preqsnOLD 4332 suceloni 6905 tz7.48lem 7423 msq0i 10553 msq0d 10555 prmdvdsexp 15265 metn0 21975 rrxcph 22988 nb3graprlem2 25981 pdivsq 30888 nofulllem5 31105 pm11.7 37618 nb3grprlem2 40609 |
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