Proof of Theorem xrmaxiflemlub
| Step | Hyp | Ref
 | Expression | 
| 1 |   | xrmaxiflemlub.clt | 
. . 3
⊢ (𝜑 → 𝐶 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) | 
| 2 |   | xrmaxiflemlub.c | 
. . . 4
⊢ (𝜑 → 𝐶 ∈
ℝ*) | 
| 3 |   | xrmaxiflemlub.a | 
. . . . 5
⊢ (𝜑 → 𝐴 ∈
ℝ*) | 
| 4 |   | xrmaxiflemlub.b | 
. . . . 5
⊢ (𝜑 → 𝐵 ∈
ℝ*) | 
| 5 |   | xrmaxiflemcl 11410 | 
. . . . 5
⊢ ((𝐴 ∈ ℝ*
∧ 𝐵 ∈
ℝ*) → if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) ∈
ℝ*) | 
| 6 | 3, 4, 5 | syl2anc 411 | 
. . . 4
⊢ (𝜑 → if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) ∈
ℝ*) | 
| 7 |   | xrltso 9871 | 
. . . . 5
⊢  < Or
ℝ* | 
| 8 |   | sowlin 4355 | 
. . . . 5
⊢ (( <
Or ℝ* ∧ (𝐶 ∈ ℝ* ∧ if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) ∈
ℝ* ∧ 𝐴
∈ ℝ*)) → (𝐶 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) → (𝐶 < 𝐴 ∨ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))))) | 
| 9 | 7, 8 | mpan 424 | 
. . . 4
⊢ ((𝐶 ∈ ℝ*
∧ if(𝐵 = +∞,
+∞, if(𝐵 = -∞,
𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) ∈
ℝ* ∧ 𝐴
∈ ℝ*) → (𝐶 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) → (𝐶 < 𝐴 ∨ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))))) | 
| 10 | 2, 6, 3, 9 | syl3anc 1249 | 
. . 3
⊢ (𝜑 → (𝐶 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) → (𝐶 < 𝐴 ∨ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))))) | 
| 11 | 1, 10 | mpd 13 | 
. 2
⊢ (𝜑 → (𝐶 < 𝐴 ∨ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))))) | 
| 12 | 1 | adantr 276 | 
. . . . 5
⊢ ((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) → 𝐶 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) | 
| 13 | 3 | adantr 276 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) → 𝐴 ∈
ℝ*) | 
| 14 | 4 | adantr 276 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) → 𝐵 ∈
ℝ*) | 
| 15 |   | simplr 528 | 
. . . . . . . . 9
⊢ (((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ 𝐵 = +∞) → 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) | 
| 16 |   | simpr 110 | 
. . . . . . . . . 10
⊢ (((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ 𝐵 = +∞) → 𝐵 = +∞) | 
| 17 | 16 | iftrued 3568 | 
. . . . . . . . 9
⊢ (((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ 𝐵 = +∞) → if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) =
+∞) | 
| 18 | 15, 17 | breqtrd 4059 | 
. . . . . . . 8
⊢ (((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ 𝐵 = +∞) → 𝐴 < +∞) | 
| 19 | 18, 16 | breqtrrd 4061 | 
. . . . . . 7
⊢ (((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ 𝐵 = +∞) → 𝐴 < 𝐵) | 
| 20 |   | simplr 528 | 
. . . . . . . . . . . 12
⊢ (((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) → 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) | 
| 21 |   | simpr 110 | 
. . . . . . . . . . . . 13
⊢ (((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) → ¬ 𝐵 = +∞) | 
| 22 | 21 | iffalsed 3571 | 
. . . . . . . . . . . 12
⊢ (((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) → if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) = if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) | 
| 23 | 20, 22 | breqtrd 4059 | 
. . . . . . . . . . 11
⊢ (((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) → 𝐴 < if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) | 
| 24 | 23 | adantr 276 | 
. . . . . . . . . 10
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ 𝐵 = -∞) → 𝐴 < if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) | 
| 25 |   | simpr 110 | 
. . . . . . . . . . 11
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ 𝐵 = -∞) → 𝐵 = -∞) | 
| 26 | 25 | iftrued 3568 | 
. . . . . . . . . 10
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ 𝐵 = -∞) → if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))) = 𝐴) | 
| 27 | 24, 26 | breqtrd 4059 | 
. . . . . . . . 9
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ 𝐵 = -∞) → 𝐴 < 𝐴) | 
| 28 |   | xrltnr 9854 | 
. . . . . . . . . . 11
⊢ (𝐴 ∈ ℝ*
→ ¬ 𝐴 < 𝐴) | 
| 29 | 3, 28 | syl 14 | 
. . . . . . . . . 10
⊢ (𝜑 → ¬ 𝐴 < 𝐴) | 
| 30 | 29 | ad3antrrr 492 | 
. . . . . . . . 9
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ 𝐵 = -∞) → ¬ 𝐴 < 𝐴) | 
| 31 | 27, 30 | pm2.21dd 621 | 
. . . . . . . 8
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ 𝐵 = -∞) → 𝐴 < 𝐵) | 
| 32 | 23 | adantr 276 | 
. . . . . . . . . . . . 13
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) → 𝐴 < if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) | 
| 33 |   | simpr 110 | 
. . . . . . . . . . . . . 14
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) → ¬ 𝐵 = -∞) | 
| 34 | 33 | iffalsed 3571 | 
. . . . . . . . . . . . 13
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) → if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))) = if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))) | 
| 35 | 32, 34 | breqtrd 4059 | 
. . . . . . . . . . . 12
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) → 𝐴 < if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))) | 
| 36 | 35 | adantr 276 | 
. . . . . . . . . . 11
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ 𝐴 = +∞) → 𝐴 < if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))) | 
| 37 |   | simpr 110 | 
. . . . . . . . . . . 12
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ 𝐴 = +∞) → 𝐴 = +∞) | 
| 38 | 37 | iftrued 3568 | 
. . . . . . . . . . 11
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ 𝐴 = +∞) → if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))) =
+∞) | 
| 39 | 36, 38 | breqtrd 4059 | 
. . . . . . . . . 10
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ 𝐴 = +∞) → 𝐴 < +∞) | 
| 40 |   | nltpnft 9889 | 
. . . . . . . . . . . . 13
⊢ (𝐴 ∈ ℝ*
→ (𝐴 = +∞ ↔
¬ 𝐴 <
+∞)) | 
| 41 | 3, 40 | syl 14 | 
. . . . . . . . . . . 12
⊢ (𝜑 → (𝐴 = +∞ ↔ ¬ 𝐴 < +∞)) | 
| 42 | 41 | ad4antr 494 | 
. . . . . . . . . . 11
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ 𝐴 = +∞) → (𝐴 = +∞ ↔ ¬ 𝐴 <
+∞)) | 
| 43 | 37, 42 | mpbid 147 | 
. . . . . . . . . 10
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ 𝐴 = +∞) → ¬ 𝐴 < +∞) | 
| 44 | 39, 43 | pm2.21dd 621 | 
. . . . . . . . 9
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ 𝐴 = +∞) → 𝐴 < 𝐵) | 
| 45 | 35 | adantr 276 | 
. . . . . . . . . . . . 13
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) → 𝐴 < if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))) | 
| 46 |   | simpr 110 | 
. . . . . . . . . . . . . 14
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) → ¬ 𝐴 = +∞) | 
| 47 | 46 | iffalsed 3571 | 
. . . . . . . . . . . . 13
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) → if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))) = if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))) | 
| 48 | 45, 47 | breqtrd 4059 | 
. . . . . . . . . . . 12
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) → 𝐴 < if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))) | 
| 49 | 48 | adantr 276 | 
. . . . . . . . . . 11
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ 𝐴 = -∞) → 𝐴 < if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))) | 
| 50 |   | simpr 110 | 
. . . . . . . . . . . 12
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ 𝐴 = -∞) → 𝐴 = -∞) | 
| 51 | 50 | iftrued 3568 | 
. . . . . . . . . . 11
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ 𝐴 = -∞) → if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )) = 𝐵) | 
| 52 | 49, 51 | breqtrd 4059 | 
. . . . . . . . . 10
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ 𝐴 = -∞) → 𝐴 < 𝐵) | 
| 53 | 29 | ad5antr 496 | 
. . . . . . . . . . 11
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → ¬ 𝐴 < 𝐴) | 
| 54 |   | simp-5l 543 | 
. . . . . . . . . . . . . . . . 17
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → 𝜑) | 
| 55 |   | simp-4r 542 | 
. . . . . . . . . . . . . . . . 17
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → ¬ 𝐵 = +∞) | 
| 56 | 54, 55 | jca 306 | 
. . . . . . . . . . . . . . . 16
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → (𝜑 ∧ ¬ 𝐵 = +∞)) | 
| 57 |   | simpllr 534 | 
. . . . . . . . . . . . . . . 16
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → ¬ 𝐵 = -∞) | 
| 58 | 56, 57 | jca 306 | 
. . . . . . . . . . . . . . 15
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → ((𝜑 ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞)) | 
| 59 |   | simplr 528 | 
. . . . . . . . . . . . . . 15
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → ¬ 𝐴 = +∞) | 
| 60 | 58, 59 | jca 306 | 
. . . . . . . . . . . . . 14
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → (((𝜑 ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞)) | 
| 61 |   | simpr 110 | 
. . . . . . . . . . . . . 14
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → ¬ 𝐴 = -∞) | 
| 62 |   | simplr 528 | 
. . . . . . . . . . . . . . 15
⊢
(((((𝜑 ∧ ¬
𝐵 = +∞) ∧ ¬
𝐵 = -∞) ∧ ¬
𝐴 = +∞) ∧ ¬
𝐴 = -∞) → ¬
𝐴 =
+∞) | 
| 63 |   | simpr 110 | 
. . . . . . . . . . . . . . 15
⊢
(((((𝜑 ∧ ¬
𝐵 = +∞) ∧ ¬
𝐵 = -∞) ∧ ¬
𝐴 = +∞) ∧ ¬
𝐴 = -∞) → ¬
𝐴 =
-∞) | 
| 64 |   | elxr 9851 | 
. . . . . . . . . . . . . . . . 17
⊢ (𝐴 ∈ ℝ*
↔ (𝐴 ∈ ℝ
∨ 𝐴 = +∞ ∨
𝐴 =
-∞)) | 
| 65 | 3, 64 | sylib 122 | 
. . . . . . . . . . . . . . . 16
⊢ (𝜑 → (𝐴 ∈ ℝ ∨ 𝐴 = +∞ ∨ 𝐴 = -∞)) | 
| 66 | 65 | ad4antr 494 | 
. . . . . . . . . . . . . . 15
⊢
(((((𝜑 ∧ ¬
𝐵 = +∞) ∧ ¬
𝐵 = -∞) ∧ ¬
𝐴 = +∞) ∧ ¬
𝐴 = -∞) → (𝐴 ∈ ℝ ∨ 𝐴 = +∞ ∨ 𝐴 = -∞)) | 
| 67 | 62, 63, 66 | ecase23d 1361 | 
. . . . . . . . . . . . . 14
⊢
(((((𝜑 ∧ ¬
𝐵 = +∞) ∧ ¬
𝐵 = -∞) ∧ ¬
𝐴 = +∞) ∧ ¬
𝐴 = -∞) → 𝐴 ∈
ℝ) | 
| 68 | 60, 61, 67 | syl2anc 411 | 
. . . . . . . . . . . . 13
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → 𝐴 ∈
ℝ) | 
| 69 |   | simp-4r 542 | 
. . . . . . . . . . . . . . 15
⊢
(((((𝜑 ∧ ¬
𝐵 = +∞) ∧ ¬
𝐵 = -∞) ∧ ¬
𝐴 = +∞) ∧ ¬
𝐴 = -∞) → ¬
𝐵 =
+∞) | 
| 70 |   | simpllr 534 | 
. . . . . . . . . . . . . . 15
⊢
(((((𝜑 ∧ ¬
𝐵 = +∞) ∧ ¬
𝐵 = -∞) ∧ ¬
𝐴 = +∞) ∧ ¬
𝐴 = -∞) → ¬
𝐵 =
-∞) | 
| 71 |   | elxr 9851 | 
. . . . . . . . . . . . . . . . 17
⊢ (𝐵 ∈ ℝ*
↔ (𝐵 ∈ ℝ
∨ 𝐵 = +∞ ∨
𝐵 =
-∞)) | 
| 72 | 4, 71 | sylib 122 | 
. . . . . . . . . . . . . . . 16
⊢ (𝜑 → (𝐵 ∈ ℝ ∨ 𝐵 = +∞ ∨ 𝐵 = -∞)) | 
| 73 | 72 | ad4antr 494 | 
. . . . . . . . . . . . . . 15
⊢
(((((𝜑 ∧ ¬
𝐵 = +∞) ∧ ¬
𝐵 = -∞) ∧ ¬
𝐴 = +∞) ∧ ¬
𝐴 = -∞) → (𝐵 ∈ ℝ ∨ 𝐵 = +∞ ∨ 𝐵 = -∞)) | 
| 74 | 69, 70, 73 | ecase23d 1361 | 
. . . . . . . . . . . . . 14
⊢
(((((𝜑 ∧ ¬
𝐵 = +∞) ∧ ¬
𝐵 = -∞) ∧ ¬
𝐴 = +∞) ∧ ¬
𝐴 = -∞) → 𝐵 ∈
ℝ) | 
| 75 | 60, 61, 74 | syl2anc 411 | 
. . . . . . . . . . . . 13
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → 𝐵 ∈
ℝ) | 
| 76 | 48 | adantr 276 | 
. . . . . . . . . . . . . 14
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → 𝐴 < if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))) | 
| 77 | 61 | iffalsed 3571 | 
. . . . . . . . . . . . . 14
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )) = sup({𝐴, 𝐵}, ℝ, < )) | 
| 78 | 76, 77 | breqtrd 4059 | 
. . . . . . . . . . . . 13
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → 𝐴 < sup({𝐴, 𝐵}, ℝ, < )) | 
| 79 |   | maxleastlt 11380 | 
. . . . . . . . . . . . 13
⊢ (((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) ∧ (𝐴 ∈ ℝ ∧ 𝐴 < sup({𝐴, 𝐵}, ℝ, < ))) → (𝐴 < 𝐴 ∨ 𝐴 < 𝐵)) | 
| 80 | 68, 75, 68, 78, 79 | syl22anc 1250 | 
. . . . . . . . . . . 12
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → (𝐴 < 𝐴 ∨ 𝐴 < 𝐵)) | 
| 81 | 80 | orcomd 730 | 
. . . . . . . . . . 11
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → (𝐴 < 𝐵 ∨ 𝐴 < 𝐴)) | 
| 82 | 53, 81 | ecased 1360 | 
. . . . . . . . . 10
⊢
((((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) ∧ ¬ 𝐴 = -∞) → 𝐴 < 𝐵) | 
| 83 |   | xrmnfdc 9918 | 
. . . . . . . . . . . 12
⊢ (𝐴 ∈ ℝ*
→ DECID 𝐴 = -∞) | 
| 84 |   | exmiddc 837 | 
. . . . . . . . . . . 12
⊢
(DECID 𝐴 = -∞ → (𝐴 = -∞ ∨ ¬ 𝐴 = -∞)) | 
| 85 | 3, 83, 84 | 3syl 17 | 
. . . . . . . . . . 11
⊢ (𝜑 → (𝐴 = -∞ ∨ ¬ 𝐴 = -∞)) | 
| 86 | 85 | ad4antr 494 | 
. . . . . . . . . 10
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) → (𝐴 = -∞ ∨ ¬ 𝐴 = -∞)) | 
| 87 | 52, 82, 86 | mpjaodan 799 | 
. . . . . . . . 9
⊢
(((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) ∧ ¬ 𝐴 = +∞) → 𝐴 < 𝐵) | 
| 88 |   | xrpnfdc 9917 | 
. . . . . . . . . . 11
⊢ (𝐴 ∈ ℝ*
→ DECID 𝐴 = +∞) | 
| 89 |   | exmiddc 837 | 
. . . . . . . . . . 11
⊢
(DECID 𝐴 = +∞ → (𝐴 = +∞ ∨ ¬ 𝐴 = +∞)) | 
| 90 | 3, 88, 89 | 3syl 17 | 
. . . . . . . . . 10
⊢ (𝜑 → (𝐴 = +∞ ∨ ¬ 𝐴 = +∞)) | 
| 91 | 90 | ad3antrrr 492 | 
. . . . . . . . 9
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) → (𝐴 = +∞ ∨ ¬ 𝐴 = +∞)) | 
| 92 | 44, 87, 91 | mpjaodan 799 | 
. . . . . . . 8
⊢ ((((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) ∧ ¬ 𝐵 = -∞) → 𝐴 < 𝐵) | 
| 93 |   | xrmnfdc 9918 | 
. . . . . . . . . 10
⊢ (𝐵 ∈ ℝ*
→ DECID 𝐵 = -∞) | 
| 94 |   | exmiddc 837 | 
. . . . . . . . . 10
⊢
(DECID 𝐵 = -∞ → (𝐵 = -∞ ∨ ¬ 𝐵 = -∞)) | 
| 95 | 4, 93, 94 | 3syl 17 | 
. . . . . . . . 9
⊢ (𝜑 → (𝐵 = -∞ ∨ ¬ 𝐵 = -∞)) | 
| 96 | 95 | ad2antrr 488 | 
. . . . . . . 8
⊢ (((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) → (𝐵 = -∞ ∨ ¬ 𝐵 = -∞)) | 
| 97 | 31, 92, 96 | mpjaodan 799 | 
. . . . . . 7
⊢ (((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) ∧ ¬ 𝐵 = +∞) → 𝐴 < 𝐵) | 
| 98 |   | xrpnfdc 9917 | 
. . . . . . . 8
⊢ (𝐵 ∈ ℝ*
→ DECID 𝐵 = +∞) | 
| 99 |   | exmiddc 837 | 
. . . . . . . 8
⊢
(DECID 𝐵 = +∞ → (𝐵 = +∞ ∨ ¬ 𝐵 = +∞)) | 
| 100 | 14, 98, 99 | 3syl 17 | 
. . . . . . 7
⊢ ((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) → (𝐵 = +∞ ∨ ¬ 𝐵 = +∞)) | 
| 101 | 19, 97, 100 | mpjaodan 799 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) → 𝐴 < 𝐵) | 
| 102 | 13, 14, 101 | xrmaxiflemab 11412 | 
. . . . 5
⊢ ((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) → if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) = 𝐵) | 
| 103 | 12, 102 | breqtrd 4059 | 
. . . 4
⊢ ((𝜑 ∧ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) → 𝐶 < 𝐵) | 
| 104 | 103 | ex 115 | 
. . 3
⊢ (𝜑 → (𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < ))))) → 𝐶 < 𝐵)) | 
| 105 | 104 | orim2d 789 | 
. 2
⊢ (𝜑 → ((𝐶 < 𝐴 ∨ 𝐴 < if(𝐵 = +∞, +∞, if(𝐵 = -∞, 𝐴, if(𝐴 = +∞, +∞, if(𝐴 = -∞, 𝐵, sup({𝐴, 𝐵}, ℝ, < )))))) → (𝐶 < 𝐴 ∨ 𝐶 < 𝐵))) | 
| 106 | 11, 105 | mpd 13 | 
1
⊢ (𝜑 → (𝐶 < 𝐴 ∨ 𝐶 < 𝐵)) |