Proof of Theorem fsn2
| Step | Hyp | Ref
 | Expression | 
| 1 |   | ffn 5407 | 
. . 3
⊢ (𝐹:{𝐴}⟶𝐵 → 𝐹 Fn {𝐴}) | 
| 2 |   | fsn2.1 | 
. . . . 5
⊢ 𝐴 ∈ V | 
| 3 | 2 | snid 3653 | 
. . . 4
⊢ 𝐴 ∈ {𝐴} | 
| 4 |   | funfvex 5575 | 
. . . . 5
⊢ ((Fun
𝐹 ∧ 𝐴 ∈ dom 𝐹) → (𝐹‘𝐴) ∈ V) | 
| 5 | 4 | funfni 5358 | 
. . . 4
⊢ ((𝐹 Fn {𝐴} ∧ 𝐴 ∈ {𝐴}) → (𝐹‘𝐴) ∈ V) | 
| 6 | 3, 5 | mpan2 425 | 
. . 3
⊢ (𝐹 Fn {𝐴} → (𝐹‘𝐴) ∈ V) | 
| 7 | 1, 6 | syl 14 | 
. 2
⊢ (𝐹:{𝐴}⟶𝐵 → (𝐹‘𝐴) ∈ V) | 
| 8 |   | elex 2774 | 
. . 3
⊢ ((𝐹‘𝐴) ∈ 𝐵 → (𝐹‘𝐴) ∈ V) | 
| 9 | 8 | adantr 276 | 
. 2
⊢ (((𝐹‘𝐴) ∈ 𝐵 ∧ 𝐹 = {〈𝐴, (𝐹‘𝐴)〉}) → (𝐹‘𝐴) ∈ V) | 
| 10 |   | ffvelcdm 5695 | 
. . . . . 6
⊢ ((𝐹:{𝐴}⟶𝐵 ∧ 𝐴 ∈ {𝐴}) → (𝐹‘𝐴) ∈ 𝐵) | 
| 11 | 3, 10 | mpan2 425 | 
. . . . 5
⊢ (𝐹:{𝐴}⟶𝐵 → (𝐹‘𝐴) ∈ 𝐵) | 
| 12 |   | dffn3 5418 | 
. . . . . . . 8
⊢ (𝐹 Fn {𝐴} ↔ 𝐹:{𝐴}⟶ran 𝐹) | 
| 13 | 12 | biimpi 120 | 
. . . . . . 7
⊢ (𝐹 Fn {𝐴} → 𝐹:{𝐴}⟶ran 𝐹) | 
| 14 |   | imadmrn 5019 | 
. . . . . . . . . 10
⊢ (𝐹 “ dom 𝐹) = ran 𝐹 | 
| 15 |   | fndm 5357 | 
. . . . . . . . . . 11
⊢ (𝐹 Fn {𝐴} → dom 𝐹 = {𝐴}) | 
| 16 | 15 | imaeq2d 5009 | 
. . . . . . . . . 10
⊢ (𝐹 Fn {𝐴} → (𝐹 “ dom 𝐹) = (𝐹 “ {𝐴})) | 
| 17 | 14, 16 | eqtr3id 2243 | 
. . . . . . . . 9
⊢ (𝐹 Fn {𝐴} → ran 𝐹 = (𝐹 “ {𝐴})) | 
| 18 |   | fnsnfv 5620 | 
. . . . . . . . . 10
⊢ ((𝐹 Fn {𝐴} ∧ 𝐴 ∈ {𝐴}) → {(𝐹‘𝐴)} = (𝐹 “ {𝐴})) | 
| 19 | 3, 18 | mpan2 425 | 
. . . . . . . . 9
⊢ (𝐹 Fn {𝐴} → {(𝐹‘𝐴)} = (𝐹 “ {𝐴})) | 
| 20 | 17, 19 | eqtr4d 2232 | 
. . . . . . . 8
⊢ (𝐹 Fn {𝐴} → ran 𝐹 = {(𝐹‘𝐴)}) | 
| 21 |   | feq3 5392 | 
. . . . . . . 8
⊢ (ran
𝐹 = {(𝐹‘𝐴)} → (𝐹:{𝐴}⟶ran 𝐹 ↔ 𝐹:{𝐴}⟶{(𝐹‘𝐴)})) | 
| 22 | 20, 21 | syl 14 | 
. . . . . . 7
⊢ (𝐹 Fn {𝐴} → (𝐹:{𝐴}⟶ran 𝐹 ↔ 𝐹:{𝐴}⟶{(𝐹‘𝐴)})) | 
| 23 | 13, 22 | mpbid 147 | 
. . . . . 6
⊢ (𝐹 Fn {𝐴} → 𝐹:{𝐴}⟶{(𝐹‘𝐴)}) | 
| 24 | 1, 23 | syl 14 | 
. . . . 5
⊢ (𝐹:{𝐴}⟶𝐵 → 𝐹:{𝐴}⟶{(𝐹‘𝐴)}) | 
| 25 | 11, 24 | jca 306 | 
. . . 4
⊢ (𝐹:{𝐴}⟶𝐵 → ((𝐹‘𝐴) ∈ 𝐵 ∧ 𝐹:{𝐴}⟶{(𝐹‘𝐴)})) | 
| 26 |   | snssi 3766 | 
. . . . 5
⊢ ((𝐹‘𝐴) ∈ 𝐵 → {(𝐹‘𝐴)} ⊆ 𝐵) | 
| 27 |   | fss 5419 | 
. . . . . 6
⊢ ((𝐹:{𝐴}⟶{(𝐹‘𝐴)} ∧ {(𝐹‘𝐴)} ⊆ 𝐵) → 𝐹:{𝐴}⟶𝐵) | 
| 28 | 27 | ancoms 268 | 
. . . . 5
⊢ (({(𝐹‘𝐴)} ⊆ 𝐵 ∧ 𝐹:{𝐴}⟶{(𝐹‘𝐴)}) → 𝐹:{𝐴}⟶𝐵) | 
| 29 | 26, 28 | sylan 283 | 
. . . 4
⊢ (((𝐹‘𝐴) ∈ 𝐵 ∧ 𝐹:{𝐴}⟶{(𝐹‘𝐴)}) → 𝐹:{𝐴}⟶𝐵) | 
| 30 | 25, 29 | impbii 126 | 
. . 3
⊢ (𝐹:{𝐴}⟶𝐵 ↔ ((𝐹‘𝐴) ∈ 𝐵 ∧ 𝐹:{𝐴}⟶{(𝐹‘𝐴)})) | 
| 31 |   | fsng 5735 | 
. . . . 5
⊢ ((𝐴 ∈ V ∧ (𝐹‘𝐴) ∈ V) → (𝐹:{𝐴}⟶{(𝐹‘𝐴)} ↔ 𝐹 = {〈𝐴, (𝐹‘𝐴)〉})) | 
| 32 | 2, 31 | mpan 424 | 
. . . 4
⊢ ((𝐹‘𝐴) ∈ V → (𝐹:{𝐴}⟶{(𝐹‘𝐴)} ↔ 𝐹 = {〈𝐴, (𝐹‘𝐴)〉})) | 
| 33 | 32 | anbi2d 464 | 
. . 3
⊢ ((𝐹‘𝐴) ∈ V → (((𝐹‘𝐴) ∈ 𝐵 ∧ 𝐹:{𝐴}⟶{(𝐹‘𝐴)}) ↔ ((𝐹‘𝐴) ∈ 𝐵 ∧ 𝐹 = {〈𝐴, (𝐹‘𝐴)〉}))) | 
| 34 | 30, 33 | bitrid 192 | 
. 2
⊢ ((𝐹‘𝐴) ∈ V → (𝐹:{𝐴}⟶𝐵 ↔ ((𝐹‘𝐴) ∈ 𝐵 ∧ 𝐹 = {〈𝐴, (𝐹‘𝐴)〉}))) | 
| 35 | 7, 9, 34 | pm5.21nii 705 | 
1
⊢ (𝐹:{𝐴}⟶𝐵 ↔ ((𝐹‘𝐴) ∈ 𝐵 ∧ 𝐹 = {〈𝐴, (𝐹‘𝐴)〉})) |