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Mirrors > Home > MPE Home > Th. List > con3 | Unicode version |
Description: Contraposition. Theorem *2.16 of [WhiteheadRussell] p. 103. This was the fourth axiom of Frege, specifically Proposition 28 of [Frege1879] p. 43. (Contributed by NM, 29-Dec-1992.) (Proof shortened by Wolf Lammen, 13-Feb-2013.) |
Ref | Expression |
---|---|
con3 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | id 22 | . 2 | |
2 | 1 | con3d 133 | 1 |
Colors of variables: wff setvar class |
Syntax hints: -. wn 3 -> wi 4 |
This theorem is referenced by: pm2.65 172 con34b 292 nic-ax 1506 nic-axALT 1507 eximOLD 1655 axc10 2004 ax12indn 2273 rexim 2922 ralf0 3936 dfon2lem9 29223 hbntg 29238 naim1 29850 naim2 29851 lukshef-ax2 29880 nrhmzr 32679 vk15.4j 33298 tratrb 33307 hbntal 33326 tratrbVD 33661 con5VD 33700 vk15.4jVD 33714 bj-axc10v 34277 cvrexchlem 35143 cvratlem 35145 axfrege28 37856 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 |
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