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Mirrors > Home > ILE Home > Th. List > df2nd2 | GIF version |
Description: An alternate possible definition of the 2nd function. (Contributed by NM, 10-Aug-2006.) (Revised by Mario Carneiro, 31-Aug-2015.) |
Ref | Expression |
---|---|
df2nd2 | ⊢ {〈〈𝑥, 𝑦〉, 𝑧〉 ∣ 𝑧 = 𝑦} = (2nd ↾ (V × V)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | fo2nd 6056 | . . . . 5 ⊢ 2nd :V–onto→V | |
2 | fofn 5347 | . . . . 5 ⊢ (2nd :V–onto→V → 2nd Fn V) | |
3 | dffn5im 5467 | . . . . 5 ⊢ (2nd Fn V → 2nd = (𝑤 ∈ V ↦ (2nd ‘𝑤))) | |
4 | 1, 2, 3 | mp2b 8 | . . . 4 ⊢ 2nd = (𝑤 ∈ V ↦ (2nd ‘𝑤)) |
5 | mptv 4025 | . . . 4 ⊢ (𝑤 ∈ V ↦ (2nd ‘𝑤)) = {〈𝑤, 𝑧〉 ∣ 𝑧 = (2nd ‘𝑤)} | |
6 | 4, 5 | eqtri 2160 | . . 3 ⊢ 2nd = {〈𝑤, 𝑧〉 ∣ 𝑧 = (2nd ‘𝑤)} |
7 | 6 | reseq1i 4815 | . 2 ⊢ (2nd ↾ (V × V)) = ({〈𝑤, 𝑧〉 ∣ 𝑧 = (2nd ‘𝑤)} ↾ (V × V)) |
8 | resopab 4863 | . 2 ⊢ ({〈𝑤, 𝑧〉 ∣ 𝑧 = (2nd ‘𝑤)} ↾ (V × V)) = {〈𝑤, 𝑧〉 ∣ (𝑤 ∈ (V × V) ∧ 𝑧 = (2nd ‘𝑤))} | |
9 | vex 2689 | . . . . 5 ⊢ 𝑥 ∈ V | |
10 | vex 2689 | . . . . 5 ⊢ 𝑦 ∈ V | |
11 | 9, 10 | op2ndd 6047 | . . . 4 ⊢ (𝑤 = 〈𝑥, 𝑦〉 → (2nd ‘𝑤) = 𝑦) |
12 | 11 | eqeq2d 2151 | . . 3 ⊢ (𝑤 = 〈𝑥, 𝑦〉 → (𝑧 = (2nd ‘𝑤) ↔ 𝑧 = 𝑦)) |
13 | 12 | dfoprab3 6089 | . 2 ⊢ {〈𝑤, 𝑧〉 ∣ (𝑤 ∈ (V × V) ∧ 𝑧 = (2nd ‘𝑤))} = {〈〈𝑥, 𝑦〉, 𝑧〉 ∣ 𝑧 = 𝑦} |
14 | 7, 8, 13 | 3eqtrri 2165 | 1 ⊢ {〈〈𝑥, 𝑦〉, 𝑧〉 ∣ 𝑧 = 𝑦} = (2nd ↾ (V × V)) |
Colors of variables: wff set class |
Syntax hints: ∧ wa 103 = wceq 1331 ∈ wcel 1480 Vcvv 2686 〈cop 3530 {copab 3988 ↦ cmpt 3989 × cxp 4537 ↾ cres 4541 Fn wfn 5118 –onto→wfo 5121 ‘cfv 5123 {coprab 5775 2nd c2nd 6037 |
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-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-pow 4098 ax-pr 4131 ax-un 4355 |
This theorem depends on definitions: df-bi 116 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-ral 2421 df-rex 2422 df-v 2688 df-sbc 2910 df-un 3075 df-in 3077 df-ss 3084 df-pw 3512 df-sn 3533 df-pr 3534 df-op 3536 df-uni 3737 df-br 3930 df-opab 3990 df-mpt 3991 df-id 4215 df-xp 4545 df-rel 4546 df-cnv 4547 df-co 4548 df-dm 4549 df-rn 4550 df-res 4551 df-iota 5088 df-fun 5125 df-fn 5126 df-f 5127 df-fo 5129 df-fv 5131 df-oprab 5778 df-1st 6038 df-2nd 6039 |
This theorem is referenced by: (None) |
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