Proof of Theorem upgrex
Step | Hyp | Ref
| Expression |
1 | | isupgr.v |
. . . . 5
⊢ 𝑉 = (Vtx‘𝐺) |
2 | | isupgr.e |
. . . . 5
⊢ 𝐸 = (iEdg‘𝐺) |
3 | 1, 2 | upgrn0 27459 |
. . . 4
⊢ ((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) → (𝐸‘𝐹) ≠ ∅) |
4 | | n0 4280 |
. . . 4
⊢ ((𝐸‘𝐹) ≠ ∅ ↔ ∃𝑥 𝑥 ∈ (𝐸‘𝐹)) |
5 | 3, 4 | sylib 217 |
. . 3
⊢ ((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) → ∃𝑥 𝑥 ∈ (𝐸‘𝐹)) |
6 | | simp1 1135 |
. . . . . . . 8
⊢ ((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) → 𝐺 ∈ UPGraph) |
7 | | fndm 6536 |
. . . . . . . . . . . . 13
⊢ (𝐸 Fn 𝐴 → dom 𝐸 = 𝐴) |
8 | 7 | eqcomd 2744 |
. . . . . . . . . . . 12
⊢ (𝐸 Fn 𝐴 → 𝐴 = dom 𝐸) |
9 | 8 | eleq2d 2824 |
. . . . . . . . . . 11
⊢ (𝐸 Fn 𝐴 → (𝐹 ∈ 𝐴 ↔ 𝐹 ∈ dom 𝐸)) |
10 | 9 | biimpd 228 |
. . . . . . . . . 10
⊢ (𝐸 Fn 𝐴 → (𝐹 ∈ 𝐴 → 𝐹 ∈ dom 𝐸)) |
11 | 10 | a1i 11 |
. . . . . . . . 9
⊢ (𝐺 ∈ UPGraph → (𝐸 Fn 𝐴 → (𝐹 ∈ 𝐴 → 𝐹 ∈ dom 𝐸))) |
12 | 11 | 3imp 1110 |
. . . . . . . 8
⊢ ((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) → 𝐹 ∈ dom 𝐸) |
13 | 1, 2 | upgrss 27458 |
. . . . . . . 8
⊢ ((𝐺 ∈ UPGraph ∧ 𝐹 ∈ dom 𝐸) → (𝐸‘𝐹) ⊆ 𝑉) |
14 | 6, 12, 13 | syl2anc 584 |
. . . . . . 7
⊢ ((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) → (𝐸‘𝐹) ⊆ 𝑉) |
15 | 14 | sselda 3921 |
. . . . . 6
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) → 𝑥 ∈ 𝑉) |
16 | 15 | adantr 481 |
. . . . . . . 8
⊢ ((((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) ∧ ((𝐸‘𝐹) ∖ {𝑥}) = ∅) → 𝑥 ∈ 𝑉) |
17 | | simpr 485 |
. . . . . . . . . 10
⊢ ((((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) ∧ ((𝐸‘𝐹) ∖ {𝑥}) = ∅) → ((𝐸‘𝐹) ∖ {𝑥}) = ∅) |
18 | | ssdif0 4297 |
. . . . . . . . . 10
⊢ ((𝐸‘𝐹) ⊆ {𝑥} ↔ ((𝐸‘𝐹) ∖ {𝑥}) = ∅) |
19 | 17, 18 | sylibr 233 |
. . . . . . . . 9
⊢ ((((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) ∧ ((𝐸‘𝐹) ∖ {𝑥}) = ∅) → (𝐸‘𝐹) ⊆ {𝑥}) |
20 | | simpr 485 |
. . . . . . . . . . 11
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) → 𝑥 ∈ (𝐸‘𝐹)) |
21 | 20 | snssd 4742 |
. . . . . . . . . 10
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) → {𝑥} ⊆ (𝐸‘𝐹)) |
22 | 21 | adantr 481 |
. . . . . . . . 9
⊢ ((((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) ∧ ((𝐸‘𝐹) ∖ {𝑥}) = ∅) → {𝑥} ⊆ (𝐸‘𝐹)) |
23 | 19, 22 | eqssd 3938 |
. . . . . . . 8
⊢ ((((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) ∧ ((𝐸‘𝐹) ∖ {𝑥}) = ∅) → (𝐸‘𝐹) = {𝑥}) |
24 | | preq2 4670 |
. . . . . . . . . 10
⊢ (𝑦 = 𝑥 → {𝑥, 𝑦} = {𝑥, 𝑥}) |
25 | | dfsn2 4574 |
. . . . . . . . . 10
⊢ {𝑥} = {𝑥, 𝑥} |
26 | 24, 25 | eqtr4di 2796 |
. . . . . . . . 9
⊢ (𝑦 = 𝑥 → {𝑥, 𝑦} = {𝑥}) |
27 | 26 | rspceeqv 3575 |
. . . . . . . 8
⊢ ((𝑥 ∈ 𝑉 ∧ (𝐸‘𝐹) = {𝑥}) → ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦}) |
28 | 16, 23, 27 | syl2anc 584 |
. . . . . . 7
⊢ ((((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) ∧ ((𝐸‘𝐹) ∖ {𝑥}) = ∅) → ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦}) |
29 | | n0 4280 |
. . . . . . . 8
⊢ (((𝐸‘𝐹) ∖ {𝑥}) ≠ ∅ ↔ ∃𝑦 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥})) |
30 | 14 | adantr 481 |
. . . . . . . . . . . . . 14
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → (𝐸‘𝐹) ⊆ 𝑉) |
31 | | simprr 770 |
. . . . . . . . . . . . . . 15
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥})) |
32 | 31 | eldifad 3899 |
. . . . . . . . . . . . . 14
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → 𝑦 ∈ (𝐸‘𝐹)) |
33 | 30, 32 | sseldd 3922 |
. . . . . . . . . . . . 13
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → 𝑦 ∈ 𝑉) |
34 | 1, 2 | upgrfi 27461 |
. . . . . . . . . . . . . . . 16
⊢ ((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) → (𝐸‘𝐹) ∈ Fin) |
35 | 34 | adantr 481 |
. . . . . . . . . . . . . . 15
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → (𝐸‘𝐹) ∈ Fin) |
36 | | simprl 768 |
. . . . . . . . . . . . . . . 16
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → 𝑥 ∈ (𝐸‘𝐹)) |
37 | 36, 32 | prssd 4755 |
. . . . . . . . . . . . . . 15
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → {𝑥, 𝑦} ⊆ (𝐸‘𝐹)) |
38 | | fvex 6787 |
. . . . . . . . . . . . . . . . 17
⊢ (𝐸‘𝐹) ∈ V |
39 | | ssdomg 8786 |
. . . . . . . . . . . . . . . . 17
⊢ ((𝐸‘𝐹) ∈ V → ({𝑥, 𝑦} ⊆ (𝐸‘𝐹) → {𝑥, 𝑦} ≼ (𝐸‘𝐹))) |
40 | 38, 37, 39 | mpsyl 68 |
. . . . . . . . . . . . . . . 16
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → {𝑥, 𝑦} ≼ (𝐸‘𝐹)) |
41 | 1, 2 | upgrle 27460 |
. . . . . . . . . . . . . . . . . . 19
⊢ ((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) → (♯‘(𝐸‘𝐹)) ≤ 2) |
42 | 41 | adantr 481 |
. . . . . . . . . . . . . . . . . 18
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → (♯‘(𝐸‘𝐹)) ≤ 2) |
43 | | eldifsni 4723 |
. . . . . . . . . . . . . . . . . . . . 21
⊢ (𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}) → 𝑦 ≠ 𝑥) |
44 | 43 | ad2antll 726 |
. . . . . . . . . . . . . . . . . . . 20
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → 𝑦 ≠ 𝑥) |
45 | 44 | necomd 2999 |
. . . . . . . . . . . . . . . . . . 19
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → 𝑥 ≠ 𝑦) |
46 | | hashprg 14110 |
. . . . . . . . . . . . . . . . . . . 20
⊢ ((𝑥 ∈ V ∧ 𝑦 ∈ V) → (𝑥 ≠ 𝑦 ↔ (♯‘{𝑥, 𝑦}) = 2)) |
47 | 46 | el2v 3440 |
. . . . . . . . . . . . . . . . . . 19
⊢ (𝑥 ≠ 𝑦 ↔ (♯‘{𝑥, 𝑦}) = 2) |
48 | 45, 47 | sylib 217 |
. . . . . . . . . . . . . . . . . 18
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → (♯‘{𝑥, 𝑦}) = 2) |
49 | 42, 48 | breqtrrd 5102 |
. . . . . . . . . . . . . . . . 17
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → (♯‘(𝐸‘𝐹)) ≤ (♯‘{𝑥, 𝑦})) |
50 | | prfi 9089 |
. . . . . . . . . . . . . . . . . 18
⊢ {𝑥, 𝑦} ∈ Fin |
51 | | hashdom 14094 |
. . . . . . . . . . . . . . . . . 18
⊢ (((𝐸‘𝐹) ∈ Fin ∧ {𝑥, 𝑦} ∈ Fin) → ((♯‘(𝐸‘𝐹)) ≤ (♯‘{𝑥, 𝑦}) ↔ (𝐸‘𝐹) ≼ {𝑥, 𝑦})) |
52 | 35, 50, 51 | sylancl 586 |
. . . . . . . . . . . . . . . . 17
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → ((♯‘(𝐸‘𝐹)) ≤ (♯‘{𝑥, 𝑦}) ↔ (𝐸‘𝐹) ≼ {𝑥, 𝑦})) |
53 | 49, 52 | mpbid 231 |
. . . . . . . . . . . . . . . 16
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → (𝐸‘𝐹) ≼ {𝑥, 𝑦}) |
54 | | sbth 8880 |
. . . . . . . . . . . . . . . 16
⊢ (({𝑥, 𝑦} ≼ (𝐸‘𝐹) ∧ (𝐸‘𝐹) ≼ {𝑥, 𝑦}) → {𝑥, 𝑦} ≈ (𝐸‘𝐹)) |
55 | 40, 53, 54 | syl2anc 584 |
. . . . . . . . . . . . . . 15
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → {𝑥, 𝑦} ≈ (𝐸‘𝐹)) |
56 | | fisseneq 9034 |
. . . . . . . . . . . . . . 15
⊢ (((𝐸‘𝐹) ∈ Fin ∧ {𝑥, 𝑦} ⊆ (𝐸‘𝐹) ∧ {𝑥, 𝑦} ≈ (𝐸‘𝐹)) → {𝑥, 𝑦} = (𝐸‘𝐹)) |
57 | 35, 37, 55, 56 | syl3anc 1370 |
. . . . . . . . . . . . . 14
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → {𝑥, 𝑦} = (𝐸‘𝐹)) |
58 | 57 | eqcomd 2744 |
. . . . . . . . . . . . 13
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → (𝐸‘𝐹) = {𝑥, 𝑦}) |
59 | 33, 58 | jca 512 |
. . . . . . . . . . . 12
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ (𝑥 ∈ (𝐸‘𝐹) ∧ 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}))) → (𝑦 ∈ 𝑉 ∧ (𝐸‘𝐹) = {𝑥, 𝑦})) |
60 | 59 | expr 457 |
. . . . . . . . . . 11
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) → (𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}) → (𝑦 ∈ 𝑉 ∧ (𝐸‘𝐹) = {𝑥, 𝑦}))) |
61 | 60 | eximdv 1920 |
. . . . . . . . . 10
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) → (∃𝑦 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥}) → ∃𝑦(𝑦 ∈ 𝑉 ∧ (𝐸‘𝐹) = {𝑥, 𝑦}))) |
62 | 61 | imp 407 |
. . . . . . . . 9
⊢ ((((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) ∧ ∃𝑦 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥})) → ∃𝑦(𝑦 ∈ 𝑉 ∧ (𝐸‘𝐹) = {𝑥, 𝑦})) |
63 | | df-rex 3070 |
. . . . . . . . 9
⊢
(∃𝑦 ∈
𝑉 (𝐸‘𝐹) = {𝑥, 𝑦} ↔ ∃𝑦(𝑦 ∈ 𝑉 ∧ (𝐸‘𝐹) = {𝑥, 𝑦})) |
64 | 62, 63 | sylibr 233 |
. . . . . . . 8
⊢ ((((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) ∧ ∃𝑦 𝑦 ∈ ((𝐸‘𝐹) ∖ {𝑥})) → ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦}) |
65 | 29, 64 | sylan2b 594 |
. . . . . . 7
⊢ ((((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) ∧ ((𝐸‘𝐹) ∖ {𝑥}) ≠ ∅) → ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦}) |
66 | 28, 65 | pm2.61dane 3032 |
. . . . . 6
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) → ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦}) |
67 | 15, 66 | jca 512 |
. . . . 5
⊢ (((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) ∧ 𝑥 ∈ (𝐸‘𝐹)) → (𝑥 ∈ 𝑉 ∧ ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦})) |
68 | 67 | ex 413 |
. . . 4
⊢ ((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) → (𝑥 ∈ (𝐸‘𝐹) → (𝑥 ∈ 𝑉 ∧ ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦}))) |
69 | 68 | eximdv 1920 |
. . 3
⊢ ((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) → (∃𝑥 𝑥 ∈ (𝐸‘𝐹) → ∃𝑥(𝑥 ∈ 𝑉 ∧ ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦}))) |
70 | 5, 69 | mpd 15 |
. 2
⊢ ((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) → ∃𝑥(𝑥 ∈ 𝑉 ∧ ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦})) |
71 | | df-rex 3070 |
. 2
⊢
(∃𝑥 ∈
𝑉 ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦} ↔ ∃𝑥(𝑥 ∈ 𝑉 ∧ ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦})) |
72 | 70, 71 | sylibr 233 |
1
⊢ ((𝐺 ∈ UPGraph ∧ 𝐸 Fn 𝐴 ∧ 𝐹 ∈ 𝐴) → ∃𝑥 ∈ 𝑉 ∃𝑦 ∈ 𝑉 (𝐸‘𝐹) = {𝑥, 𝑦}) |