| Step | Hyp | Ref
 | Expression | 
| 1 |   | simpr 110 | 
. . . 4
⊢ ((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) → 𝐵 ∈
ℝ) | 
| 2 |   | pnfxr 8079 | 
. . . 4
⊢ +∞
∈ ℝ* | 
| 3 |   | icossre 10029 | 
. . . 4
⊢ ((𝐵 ∈ ℝ ∧ +∞
∈ ℝ*) → (𝐵[,)+∞) ⊆
ℝ) | 
| 4 | 1, 2, 3 | sylancl 413 | 
. . 3
⊢ ((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) → (𝐵[,)+∞) ⊆
ℝ) | 
| 5 |   | ssrexv 3248 | 
. . 3
⊢ ((𝐵[,)+∞) ⊆ ℝ
→ (∃𝑗 ∈
(𝐵[,)+∞)∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑) → ∃𝑗 ∈ ℝ ∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑))) | 
| 6 | 4, 5 | syl 14 | 
. 2
⊢ ((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) →
(∃𝑗 ∈ (𝐵[,)+∞)∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑) → ∃𝑗 ∈ ℝ ∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑))) | 
| 7 |   | maxcl 11375 | 
. . . . . . 7
⊢ ((𝐵 ∈ ℝ ∧ 𝑗 ∈ ℝ) →
sup({𝐵, 𝑗}, ℝ, < ) ∈
ℝ) | 
| 8 | 7 | adantll 476 | 
. . . . . 6
⊢ (((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) →
sup({𝐵, 𝑗}, ℝ, < ) ∈
ℝ) | 
| 9 |   | maxle1 11376 | 
. . . . . . 7
⊢ ((𝐵 ∈ ℝ ∧ 𝑗 ∈ ℝ) → 𝐵 ≤ sup({𝐵, 𝑗}, ℝ, < )) | 
| 10 | 9 | adantll 476 | 
. . . . . 6
⊢ (((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) → 𝐵 ≤ sup({𝐵, 𝑗}, ℝ, < )) | 
| 11 |   | elicopnf 10044 | 
. . . . . . 7
⊢ (𝐵 ∈ ℝ →
(sup({𝐵, 𝑗}, ℝ, < ) ∈ (𝐵[,)+∞) ↔ (sup({𝐵, 𝑗}, ℝ, < ) ∈ ℝ ∧ 𝐵 ≤ sup({𝐵, 𝑗}, ℝ, < )))) | 
| 12 | 11 | ad2antlr 489 | 
. . . . . 6
⊢ (((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) →
(sup({𝐵, 𝑗}, ℝ, < ) ∈ (𝐵[,)+∞) ↔ (sup({𝐵, 𝑗}, ℝ, < ) ∈ ℝ ∧ 𝐵 ≤ sup({𝐵, 𝑗}, ℝ, < )))) | 
| 13 | 8, 10, 12 | mpbir2and 946 | 
. . . . 5
⊢ (((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) →
sup({𝐵, 𝑗}, ℝ, < ) ∈ (𝐵[,)+∞)) | 
| 14 |   | simpllr 534 | 
. . . . . . . . 9
⊢ ((((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) ∧ 𝑘 ∈ 𝐴) → 𝐵 ∈ ℝ) | 
| 15 |   | simplr 528 | 
. . . . . . . . 9
⊢ ((((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) ∧ 𝑘 ∈ 𝐴) → 𝑗 ∈ ℝ) | 
| 16 |   | simpll 527 | 
. . . . . . . . . 10
⊢ (((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) → 𝐴 ⊆
ℝ) | 
| 17 | 16 | sselda 3183 | 
. . . . . . . . 9
⊢ ((((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) ∧ 𝑘 ∈ 𝐴) → 𝑘 ∈ ℝ) | 
| 18 |   | maxleastb 11379 | 
. . . . . . . . 9
⊢ ((𝐵 ∈ ℝ ∧ 𝑗 ∈ ℝ ∧ 𝑘 ∈ ℝ) →
(sup({𝐵, 𝑗}, ℝ, < ) ≤ 𝑘 ↔ (𝐵 ≤ 𝑘 ∧ 𝑗 ≤ 𝑘))) | 
| 19 | 14, 15, 17, 18 | syl3anc 1249 | 
. . . . . . . 8
⊢ ((((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) ∧ 𝑘 ∈ 𝐴) → (sup({𝐵, 𝑗}, ℝ, < ) ≤ 𝑘 ↔ (𝐵 ≤ 𝑘 ∧ 𝑗 ≤ 𝑘))) | 
| 20 |   | simpr 110 | 
. . . . . . . 8
⊢ ((𝐵 ≤ 𝑘 ∧ 𝑗 ≤ 𝑘) → 𝑗 ≤ 𝑘) | 
| 21 | 19, 20 | biimtrdi 163 | 
. . . . . . 7
⊢ ((((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) ∧ 𝑘 ∈ 𝐴) → (sup({𝐵, 𝑗}, ℝ, < ) ≤ 𝑘 → 𝑗 ≤ 𝑘)) | 
| 22 | 21 | imim1d 75 | 
. . . . . 6
⊢ ((((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) ∧ 𝑘 ∈ 𝐴) → ((𝑗 ≤ 𝑘 → 𝜑) → (sup({𝐵, 𝑗}, ℝ, < ) ≤ 𝑘 → 𝜑))) | 
| 23 | 22 | ralimdva 2564 | 
. . . . 5
⊢ (((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) →
(∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑) → ∀𝑘 ∈ 𝐴 (sup({𝐵, 𝑗}, ℝ, < ) ≤ 𝑘 → 𝜑))) | 
| 24 |   | breq1 4036 | 
. . . . . . . 8
⊢ (𝑛 = sup({𝐵, 𝑗}, ℝ, < ) → (𝑛 ≤ 𝑘 ↔ sup({𝐵, 𝑗}, ℝ, < ) ≤ 𝑘)) | 
| 25 | 24 | imbi1d 231 | 
. . . . . . 7
⊢ (𝑛 = sup({𝐵, 𝑗}, ℝ, < ) → ((𝑛 ≤ 𝑘 → 𝜑) ↔ (sup({𝐵, 𝑗}, ℝ, < ) ≤ 𝑘 → 𝜑))) | 
| 26 | 25 | ralbidv 2497 | 
. . . . . 6
⊢ (𝑛 = sup({𝐵, 𝑗}, ℝ, < ) → (∀𝑘 ∈ 𝐴 (𝑛 ≤ 𝑘 → 𝜑) ↔ ∀𝑘 ∈ 𝐴 (sup({𝐵, 𝑗}, ℝ, < ) ≤ 𝑘 → 𝜑))) | 
| 27 | 26 | rspcev 2868 | 
. . . . 5
⊢
((sup({𝐵, 𝑗}, ℝ, < ) ∈ (𝐵[,)+∞) ∧ ∀𝑘 ∈ 𝐴 (sup({𝐵, 𝑗}, ℝ, < ) ≤ 𝑘 → 𝜑)) → ∃𝑛 ∈ (𝐵[,)+∞)∀𝑘 ∈ 𝐴 (𝑛 ≤ 𝑘 → 𝜑)) | 
| 28 | 13, 23, 27 | syl6an 1445 | 
. . . 4
⊢ (((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) ∧ 𝑗 ∈ ℝ) →
(∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑) → ∃𝑛 ∈ (𝐵[,)+∞)∀𝑘 ∈ 𝐴 (𝑛 ≤ 𝑘 → 𝜑))) | 
| 29 | 28 | rexlimdva 2614 | 
. . 3
⊢ ((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) →
(∃𝑗 ∈ ℝ
∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑) → ∃𝑛 ∈ (𝐵[,)+∞)∀𝑘 ∈ 𝐴 (𝑛 ≤ 𝑘 → 𝜑))) | 
| 30 |   | breq1 4036 | 
. . . . . 6
⊢ (𝑛 = 𝑗 → (𝑛 ≤ 𝑘 ↔ 𝑗 ≤ 𝑘)) | 
| 31 | 30 | imbi1d 231 | 
. . . . 5
⊢ (𝑛 = 𝑗 → ((𝑛 ≤ 𝑘 → 𝜑) ↔ (𝑗 ≤ 𝑘 → 𝜑))) | 
| 32 | 31 | ralbidv 2497 | 
. . . 4
⊢ (𝑛 = 𝑗 → (∀𝑘 ∈ 𝐴 (𝑛 ≤ 𝑘 → 𝜑) ↔ ∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑))) | 
| 33 | 32 | cbvrexv 2730 | 
. . 3
⊢
(∃𝑛 ∈
(𝐵[,)+∞)∀𝑘 ∈ 𝐴 (𝑛 ≤ 𝑘 → 𝜑) ↔ ∃𝑗 ∈ (𝐵[,)+∞)∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑)) | 
| 34 | 29, 33 | imbitrdi 161 | 
. 2
⊢ ((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) →
(∃𝑗 ∈ ℝ
∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑) → ∃𝑗 ∈ (𝐵[,)+∞)∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑))) | 
| 35 | 6, 34 | impbid 129 | 
1
⊢ ((𝐴 ⊆ ℝ ∧ 𝐵 ∈ ℝ) →
(∃𝑗 ∈ (𝐵[,)+∞)∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑) ↔ ∃𝑗 ∈ ℝ ∀𝑘 ∈ 𝐴 (𝑗 ≤ 𝑘 → 𝜑))) |