Proof of Theorem mapsn
| Step | Hyp | Ref
 | Expression | 
| 1 |   | map0.1 | 
. . . 4
⊢ 𝐴 ∈ V | 
| 2 |   | map0.2 | 
. . . . 5
⊢ 𝐵 ∈ V | 
| 3 | 2 | snex 4218 | 
. . . 4
⊢ {𝐵} ∈ V | 
| 4 | 1, 3 | elmap 6736 | 
. . 3
⊢ (𝑓 ∈ (𝐴 ↑𝑚 {𝐵}) ↔ 𝑓:{𝐵}⟶𝐴) | 
| 5 |   | ffn 5407 | 
. . . . . . . 8
⊢ (𝑓:{𝐵}⟶𝐴 → 𝑓 Fn {𝐵}) | 
| 6 | 2 | snid 3653 | 
. . . . . . . 8
⊢ 𝐵 ∈ {𝐵} | 
| 7 |   | fneu 5362 | 
. . . . . . . 8
⊢ ((𝑓 Fn {𝐵} ∧ 𝐵 ∈ {𝐵}) → ∃!𝑦 𝐵𝑓𝑦) | 
| 8 | 5, 6, 7 | sylancl 413 | 
. . . . . . 7
⊢ (𝑓:{𝐵}⟶𝐴 → ∃!𝑦 𝐵𝑓𝑦) | 
| 9 |   | euabsn 3692 | 
. . . . . . . 8
⊢
(∃!𝑦 𝐵𝑓𝑦 ↔ ∃𝑦{𝑦 ∣ 𝐵𝑓𝑦} = {𝑦}) | 
| 10 |   | imasng 5034 | 
. . . . . . . . . . . 12
⊢ (𝐵 ∈ V → (𝑓 “ {𝐵}) = {𝑦 ∣ 𝐵𝑓𝑦}) | 
| 11 | 2, 10 | ax-mp 5 | 
. . . . . . . . . . 11
⊢ (𝑓 “ {𝐵}) = {𝑦 ∣ 𝐵𝑓𝑦} | 
| 12 |   | fdm 5413 | 
. . . . . . . . . . . . 13
⊢ (𝑓:{𝐵}⟶𝐴 → dom 𝑓 = {𝐵}) | 
| 13 | 12 | imaeq2d 5009 | 
. . . . . . . . . . . 12
⊢ (𝑓:{𝐵}⟶𝐴 → (𝑓 “ dom 𝑓) = (𝑓 “ {𝐵})) | 
| 14 |   | imadmrn 5019 | 
. . . . . . . . . . . 12
⊢ (𝑓 “ dom 𝑓) = ran 𝑓 | 
| 15 | 13, 14 | eqtr3di 2244 | 
. . . . . . . . . . 11
⊢ (𝑓:{𝐵}⟶𝐴 → (𝑓 “ {𝐵}) = ran 𝑓) | 
| 16 | 11, 15 | eqtr3id 2243 | 
. . . . . . . . . 10
⊢ (𝑓:{𝐵}⟶𝐴 → {𝑦 ∣ 𝐵𝑓𝑦} = ran 𝑓) | 
| 17 | 16 | eqeq1d 2205 | 
. . . . . . . . 9
⊢ (𝑓:{𝐵}⟶𝐴 → ({𝑦 ∣ 𝐵𝑓𝑦} = {𝑦} ↔ ran 𝑓 = {𝑦})) | 
| 18 | 17 | exbidv 1839 | 
. . . . . . . 8
⊢ (𝑓:{𝐵}⟶𝐴 → (∃𝑦{𝑦 ∣ 𝐵𝑓𝑦} = {𝑦} ↔ ∃𝑦ran 𝑓 = {𝑦})) | 
| 19 | 9, 18 | bitrid 192 | 
. . . . . . 7
⊢ (𝑓:{𝐵}⟶𝐴 → (∃!𝑦 𝐵𝑓𝑦 ↔ ∃𝑦ran 𝑓 = {𝑦})) | 
| 20 | 8, 19 | mpbid 147 | 
. . . . . 6
⊢ (𝑓:{𝐵}⟶𝐴 → ∃𝑦ran 𝑓 = {𝑦}) | 
| 21 |   | vex 2766 | 
. . . . . . . . . . 11
⊢ 𝑦 ∈ V | 
| 22 | 21 | snid 3653 | 
. . . . . . . . . 10
⊢ 𝑦 ∈ {𝑦} | 
| 23 |   | eleq2 2260 | 
. . . . . . . . . 10
⊢ (ran
𝑓 = {𝑦} → (𝑦 ∈ ran 𝑓 ↔ 𝑦 ∈ {𝑦})) | 
| 24 | 22, 23 | mpbiri 168 | 
. . . . . . . . 9
⊢ (ran
𝑓 = {𝑦} → 𝑦 ∈ ran 𝑓) | 
| 25 |   | frn 5416 | 
. . . . . . . . . 10
⊢ (𝑓:{𝐵}⟶𝐴 → ran 𝑓 ⊆ 𝐴) | 
| 26 | 25 | sseld 3182 | 
. . . . . . . . 9
⊢ (𝑓:{𝐵}⟶𝐴 → (𝑦 ∈ ran 𝑓 → 𝑦 ∈ 𝐴)) | 
| 27 | 24, 26 | syl5 32 | 
. . . . . . . 8
⊢ (𝑓:{𝐵}⟶𝐴 → (ran 𝑓 = {𝑦} → 𝑦 ∈ 𝐴)) | 
| 28 |   | dffn4 5486 | 
. . . . . . . . . . . 12
⊢ (𝑓 Fn {𝐵} ↔ 𝑓:{𝐵}–onto→ran 𝑓) | 
| 29 | 5, 28 | sylib 122 | 
. . . . . . . . . . 11
⊢ (𝑓:{𝐵}⟶𝐴 → 𝑓:{𝐵}–onto→ran 𝑓) | 
| 30 |   | fof 5480 | 
. . . . . . . . . . 11
⊢ (𝑓:{𝐵}–onto→ran 𝑓 → 𝑓:{𝐵}⟶ran 𝑓) | 
| 31 | 29, 30 | syl 14 | 
. . . . . . . . . 10
⊢ (𝑓:{𝐵}⟶𝐴 → 𝑓:{𝐵}⟶ran 𝑓) | 
| 32 |   | feq3 5392 | 
. . . . . . . . . 10
⊢ (ran
𝑓 = {𝑦} → (𝑓:{𝐵}⟶ran 𝑓 ↔ 𝑓:{𝐵}⟶{𝑦})) | 
| 33 | 31, 32 | syl5ibcom 155 | 
. . . . . . . . 9
⊢ (𝑓:{𝐵}⟶𝐴 → (ran 𝑓 = {𝑦} → 𝑓:{𝐵}⟶{𝑦})) | 
| 34 | 2, 21 | fsn 5734 | 
. . . . . . . . 9
⊢ (𝑓:{𝐵}⟶{𝑦} ↔ 𝑓 = {〈𝐵, 𝑦〉}) | 
| 35 | 33, 34 | imbitrdi 161 | 
. . . . . . . 8
⊢ (𝑓:{𝐵}⟶𝐴 → (ran 𝑓 = {𝑦} → 𝑓 = {〈𝐵, 𝑦〉})) | 
| 36 | 27, 35 | jcad 307 | 
. . . . . . 7
⊢ (𝑓:{𝐵}⟶𝐴 → (ran 𝑓 = {𝑦} → (𝑦 ∈ 𝐴 ∧ 𝑓 = {〈𝐵, 𝑦〉}))) | 
| 37 | 36 | eximdv 1894 | 
. . . . . 6
⊢ (𝑓:{𝐵}⟶𝐴 → (∃𝑦ran 𝑓 = {𝑦} → ∃𝑦(𝑦 ∈ 𝐴 ∧ 𝑓 = {〈𝐵, 𝑦〉}))) | 
| 38 | 20, 37 | mpd 13 | 
. . . . 5
⊢ (𝑓:{𝐵}⟶𝐴 → ∃𝑦(𝑦 ∈ 𝐴 ∧ 𝑓 = {〈𝐵, 𝑦〉})) | 
| 39 |   | df-rex 2481 | 
. . . . 5
⊢
(∃𝑦 ∈
𝐴 𝑓 = {〈𝐵, 𝑦〉} ↔ ∃𝑦(𝑦 ∈ 𝐴 ∧ 𝑓 = {〈𝐵, 𝑦〉})) | 
| 40 | 38, 39 | sylibr 134 | 
. . . 4
⊢ (𝑓:{𝐵}⟶𝐴 → ∃𝑦 ∈ 𝐴 𝑓 = {〈𝐵, 𝑦〉}) | 
| 41 | 2, 21 | f1osn 5544 | 
. . . . . . . . 9
⊢
{〈𝐵, 𝑦〉}:{𝐵}–1-1-onto→{𝑦} | 
| 42 |   | f1oeq1 5492 | 
. . . . . . . . 9
⊢ (𝑓 = {〈𝐵, 𝑦〉} → (𝑓:{𝐵}–1-1-onto→{𝑦} ↔ {〈𝐵, 𝑦〉}:{𝐵}–1-1-onto→{𝑦})) | 
| 43 | 41, 42 | mpbiri 168 | 
. . . . . . . 8
⊢ (𝑓 = {〈𝐵, 𝑦〉} → 𝑓:{𝐵}–1-1-onto→{𝑦}) | 
| 44 |   | f1of 5504 | 
. . . . . . . 8
⊢ (𝑓:{𝐵}–1-1-onto→{𝑦} → 𝑓:{𝐵}⟶{𝑦}) | 
| 45 | 43, 44 | syl 14 | 
. . . . . . 7
⊢ (𝑓 = {〈𝐵, 𝑦〉} → 𝑓:{𝐵}⟶{𝑦}) | 
| 46 |   | snssi 3766 | 
. . . . . . 7
⊢ (𝑦 ∈ 𝐴 → {𝑦} ⊆ 𝐴) | 
| 47 |   | fss 5419 | 
. . . . . . 7
⊢ ((𝑓:{𝐵}⟶{𝑦} ∧ {𝑦} ⊆ 𝐴) → 𝑓:{𝐵}⟶𝐴) | 
| 48 | 45, 46, 47 | syl2an 289 | 
. . . . . 6
⊢ ((𝑓 = {〈𝐵, 𝑦〉} ∧ 𝑦 ∈ 𝐴) → 𝑓:{𝐵}⟶𝐴) | 
| 49 | 48 | expcom 116 | 
. . . . 5
⊢ (𝑦 ∈ 𝐴 → (𝑓 = {〈𝐵, 𝑦〉} → 𝑓:{𝐵}⟶𝐴)) | 
| 50 | 49 | rexlimiv 2608 | 
. . . 4
⊢
(∃𝑦 ∈
𝐴 𝑓 = {〈𝐵, 𝑦〉} → 𝑓:{𝐵}⟶𝐴) | 
| 51 | 40, 50 | impbii 126 | 
. . 3
⊢ (𝑓:{𝐵}⟶𝐴 ↔ ∃𝑦 ∈ 𝐴 𝑓 = {〈𝐵, 𝑦〉}) | 
| 52 | 4, 51 | bitri 184 | 
. 2
⊢ (𝑓 ∈ (𝐴 ↑𝑚 {𝐵}) ↔ ∃𝑦 ∈ 𝐴 𝑓 = {〈𝐵, 𝑦〉}) | 
| 53 | 52 | abbi2i 2311 | 
1
⊢ (𝐴 ↑𝑚
{𝐵}) = {𝑓 ∣ ∃𝑦 ∈ 𝐴 𝑓 = {〈𝐵, 𝑦〉}} |