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Mirrors > Home > MPE Home > Th. List > fnsnb | Structured version Visualization version GIF version |
Description: A function whose domain is a singleton can be represented as a singleton of an ordered pair. (Contributed by Jonathan Ben-Naim, 3-Jun-2011.) Revised to add reverse implication. (Revised by NM, 29-Dec-2018.) |
Ref | Expression |
---|---|
fnsnb.1 | ⊢ 𝐴 ∈ V |
Ref | Expression |
---|---|
fnsnb | ⊢ (𝐹 Fn {𝐴} ↔ 𝐹 = {〈𝐴, (𝐹‘𝐴)〉}) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | fnsnr 7185 | . . . . 5 ⊢ (𝐹 Fn {𝐴} → (𝑥 ∈ 𝐹 → 𝑥 = 〈𝐴, (𝐹‘𝐴)〉)) | |
2 | df-fn 6566 | . . . . . . . 8 ⊢ (𝐹 Fn {𝐴} ↔ (Fun 𝐹 ∧ dom 𝐹 = {𝐴})) | |
3 | fnsnb.1 | . . . . . . . . . . 11 ⊢ 𝐴 ∈ V | |
4 | 3 | snid 4667 | . . . . . . . . . 10 ⊢ 𝐴 ∈ {𝐴} |
5 | eleq2 2828 | . . . . . . . . . 10 ⊢ (dom 𝐹 = {𝐴} → (𝐴 ∈ dom 𝐹 ↔ 𝐴 ∈ {𝐴})) | |
6 | 4, 5 | mpbiri 258 | . . . . . . . . 9 ⊢ (dom 𝐹 = {𝐴} → 𝐴 ∈ dom 𝐹) |
7 | 6 | anim2i 617 | . . . . . . . 8 ⊢ ((Fun 𝐹 ∧ dom 𝐹 = {𝐴}) → (Fun 𝐹 ∧ 𝐴 ∈ dom 𝐹)) |
8 | 2, 7 | sylbi 217 | . . . . . . 7 ⊢ (𝐹 Fn {𝐴} → (Fun 𝐹 ∧ 𝐴 ∈ dom 𝐹)) |
9 | funfvop 7070 | . . . . . . 7 ⊢ ((Fun 𝐹 ∧ 𝐴 ∈ dom 𝐹) → 〈𝐴, (𝐹‘𝐴)〉 ∈ 𝐹) | |
10 | 8, 9 | syl 17 | . . . . . 6 ⊢ (𝐹 Fn {𝐴} → 〈𝐴, (𝐹‘𝐴)〉 ∈ 𝐹) |
11 | eleq1 2827 | . . . . . 6 ⊢ (𝑥 = 〈𝐴, (𝐹‘𝐴)〉 → (𝑥 ∈ 𝐹 ↔ 〈𝐴, (𝐹‘𝐴)〉 ∈ 𝐹)) | |
12 | 10, 11 | syl5ibrcom 247 | . . . . 5 ⊢ (𝐹 Fn {𝐴} → (𝑥 = 〈𝐴, (𝐹‘𝐴)〉 → 𝑥 ∈ 𝐹)) |
13 | 1, 12 | impbid 212 | . . . 4 ⊢ (𝐹 Fn {𝐴} → (𝑥 ∈ 𝐹 ↔ 𝑥 = 〈𝐴, (𝐹‘𝐴)〉)) |
14 | velsn 4647 | . . . 4 ⊢ (𝑥 ∈ {〈𝐴, (𝐹‘𝐴)〉} ↔ 𝑥 = 〈𝐴, (𝐹‘𝐴)〉) | |
15 | 13, 14 | bitr4di 289 | . . 3 ⊢ (𝐹 Fn {𝐴} → (𝑥 ∈ 𝐹 ↔ 𝑥 ∈ {〈𝐴, (𝐹‘𝐴)〉})) |
16 | 15 | eqrdv 2733 | . 2 ⊢ (𝐹 Fn {𝐴} → 𝐹 = {〈𝐴, (𝐹‘𝐴)〉}) |
17 | fvex 6920 | . . . 4 ⊢ (𝐹‘𝐴) ∈ V | |
18 | 3, 17 | fnsn 6626 | . . 3 ⊢ {〈𝐴, (𝐹‘𝐴)〉} Fn {𝐴} |
19 | fneq1 6660 | . . 3 ⊢ (𝐹 = {〈𝐴, (𝐹‘𝐴)〉} → (𝐹 Fn {𝐴} ↔ {〈𝐴, (𝐹‘𝐴)〉} Fn {𝐴})) | |
20 | 18, 19 | mpbiri 258 | . 2 ⊢ (𝐹 = {〈𝐴, (𝐹‘𝐴)〉} → 𝐹 Fn {𝐴}) |
21 | 16, 20 | impbii 209 | 1 ⊢ (𝐹 Fn {𝐴} ↔ 𝐹 = {〈𝐴, (𝐹‘𝐴)〉}) |
Colors of variables: wff setvar class |
Syntax hints: ↔ wb 206 ∧ wa 395 = wceq 1537 ∈ wcel 2106 Vcvv 3478 {csn 4631 〈cop 4637 dom cdm 5689 Fun wfun 6557 Fn wfn 6558 ‘cfv 6563 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1792 ax-4 1806 ax-5 1908 ax-6 1965 ax-7 2005 ax-8 2108 ax-9 2116 ax-10 2139 ax-12 2175 ax-ext 2706 ax-sep 5302 ax-nul 5312 ax-pr 5438 |
This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3an 1088 df-tru 1540 df-fal 1550 df-ex 1777 df-nf 1781 df-sb 2063 df-mo 2538 df-eu 2567 df-clab 2713 df-cleq 2727 df-clel 2814 df-ne 2939 df-ral 3060 df-rex 3069 df-reu 3379 df-rab 3434 df-v 3480 df-dif 3966 df-un 3968 df-in 3970 df-ss 3980 df-nul 4340 df-if 4532 df-sn 4632 df-pr 4634 df-op 4638 df-uni 4913 df-br 5149 df-opab 5211 df-id 5583 df-xp 5695 df-rel 5696 df-cnv 5697 df-co 5698 df-dm 5699 df-rn 5700 df-res 5701 df-ima 5702 df-iota 6516 df-fun 6565 df-fn 6566 df-f 6567 df-f1 6568 df-fo 6569 df-f1o 6570 df-fv 6571 |
This theorem is referenced by: fnprb 7228 |
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