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Mirrors > Home > ILE Home > Th. List > fidifsnid | Unicode version |
Description: If we remove a single element from a finite set then put it back in, we end up with the original finite set. This strengthens difsnss 3666 from subset to equality when the set is finite. (Contributed by Jim Kingdon, 9-Sep-2021.) |
Ref | Expression |
---|---|
fidifsnid |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | fidceq 6763 | . . . 4 DECID | |
2 | 1 | 3expb 1182 | . . 3 DECID |
3 | 2 | ralrimivva 2514 | . 2 DECID |
4 | dcdifsnid 6400 | . 2 DECID | |
5 | 3, 4 | sylan 281 | 1 |
Colors of variables: wff set class |
Syntax hints: wi 4 wa 103 DECID wdc 819 wceq 1331 wcel 1480 wral 2416 cdif 3068 cun 3069 csn 3527 cfn 6634 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 603 ax-in2 604 ax-io 698 ax-5 1423 ax-7 1424 ax-gen 1425 ax-ie1 1469 ax-ie2 1470 ax-8 1482 ax-10 1483 ax-11 1484 ax-i12 1485 ax-bndl 1486 ax-4 1487 ax-13 1491 ax-14 1492 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-ext 2121 ax-sep 4046 ax-nul 4054 ax-pow 4098 ax-pr 4131 ax-un 4355 ax-setind 4452 ax-iinf 4502 |
This theorem depends on definitions: df-bi 116 df-dc 820 df-3or 963 df-3an 964 df-tru 1334 df-nf 1437 df-sb 1736 df-eu 2002 df-mo 2003 df-clab 2126 df-cleq 2132 df-clel 2135 df-nfc 2270 df-ne 2309 df-ral 2421 df-rex 2422 df-v 2688 df-sbc 2910 df-dif 3073 df-un 3075 df-in 3077 df-ss 3084 df-nul 3364 df-pw 3512 df-sn 3533 df-pr 3534 df-op 3536 df-uni 3737 df-int 3772 df-br 3930 df-opab 3990 df-tr 4027 df-id 4215 df-iord 4288 df-on 4290 df-suc 4293 df-iom 4505 df-xp 4545 df-rel 4546 df-cnv 4547 df-co 4548 df-dm 4549 df-rn 4550 df-iota 5088 df-fun 5125 df-fn 5126 df-f 5127 df-f1 5128 df-fo 5129 df-f1o 5130 df-fv 5131 df-en 6635 df-fin 6637 |
This theorem is referenced by: findcard2 6783 findcard2s 6784 xpfi 6818 fisseneq 6820 zfz1isolem1 10590 |
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