| Step | Hyp | Ref
 | Expression | 
| 1 |   | ivth.1 | 
. . 3
⊢ (𝜑 → 𝐴 ∈ ℝ) | 
| 2 |   | ivth.2 | 
. . 3
⊢ (𝜑 → 𝐵 ∈ ℝ) | 
| 3 |   | ivth.3 | 
. . . 4
⊢ (𝜑 → 𝑈 ∈ ℝ) | 
| 4 | 3 | renegcld 8406 | 
. . 3
⊢ (𝜑 → -𝑈 ∈ ℝ) | 
| 5 |   | ivth.4 | 
. . 3
⊢ (𝜑 → 𝐴 < 𝐵) | 
| 6 |   | ivth.5 | 
. . 3
⊢ (𝜑 → (𝐴[,]𝐵) ⊆ 𝐷) | 
| 7 |   | ivth.7 | 
. . . 4
⊢ (𝜑 → 𝐹 ∈ (𝐷–cn→ℂ)) | 
| 8 |   | eqid 2196 | 
. . . . 5
⊢ (𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤)) = (𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤)) | 
| 9 | 8 | negfcncf 14842 | 
. . . 4
⊢ (𝐹 ∈ (𝐷–cn→ℂ) → (𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤)) ∈ (𝐷–cn→ℂ)) | 
| 10 | 7, 9 | syl 14 | 
. . 3
⊢ (𝜑 → (𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤)) ∈ (𝐷–cn→ℂ)) | 
| 11 |   | fveq2 5558 | 
. . . . . 6
⊢ (𝑤 = 𝑥 → (𝐹‘𝑤) = (𝐹‘𝑥)) | 
| 12 | 11 | negeqd 8221 | 
. . . . 5
⊢ (𝑤 = 𝑥 → -(𝐹‘𝑤) = -(𝐹‘𝑥)) | 
| 13 | 6 | sselda 3183 | 
. . . . 5
⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → 𝑥 ∈ 𝐷) | 
| 14 |   | ivth.8 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → (𝐹‘𝑥) ∈ ℝ) | 
| 15 | 14 | renegcld 8406 | 
. . . . 5
⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → -(𝐹‘𝑥) ∈ ℝ) | 
| 16 | 8, 12, 13, 15 | fvmptd3 5655 | 
. . . 4
⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝑥) = -(𝐹‘𝑥)) | 
| 17 | 16, 15 | eqeltrd 2273 | 
. . 3
⊢ ((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) → ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝑥) ∈ ℝ) | 
| 18 |   | fveq2 5558 | 
. . . . . . 7
⊢ (𝑤 = 𝐴 → (𝐹‘𝑤) = (𝐹‘𝐴)) | 
| 19 | 18 | negeqd 8221 | 
. . . . . 6
⊢ (𝑤 = 𝐴 → -(𝐹‘𝑤) = -(𝐹‘𝐴)) | 
| 20 | 1 | rexrd 8076 | 
. . . . . . . 8
⊢ (𝜑 → 𝐴 ∈
ℝ*) | 
| 21 | 2 | rexrd 8076 | 
. . . . . . . 8
⊢ (𝜑 → 𝐵 ∈
ℝ*) | 
| 22 | 1, 2, 5 | ltled 8145 | 
. . . . . . . 8
⊢ (𝜑 → 𝐴 ≤ 𝐵) | 
| 23 |   | lbicc2 10059 | 
. . . . . . . 8
⊢ ((𝐴 ∈ ℝ*
∧ 𝐵 ∈
ℝ* ∧ 𝐴
≤ 𝐵) → 𝐴 ∈ (𝐴[,]𝐵)) | 
| 24 | 20, 21, 22, 23 | syl3anc 1249 | 
. . . . . . 7
⊢ (𝜑 → 𝐴 ∈ (𝐴[,]𝐵)) | 
| 25 | 6, 24 | sseldd 3184 | 
. . . . . 6
⊢ (𝜑 → 𝐴 ∈ 𝐷) | 
| 26 |   | fveq2 5558 | 
. . . . . . . . 9
⊢ (𝑥 = 𝐴 → (𝐹‘𝑥) = (𝐹‘𝐴)) | 
| 27 | 26 | eleq1d 2265 | 
. . . . . . . 8
⊢ (𝑥 = 𝐴 → ((𝐹‘𝑥) ∈ ℝ ↔ (𝐹‘𝐴) ∈ ℝ)) | 
| 28 | 14 | ralrimiva 2570 | 
. . . . . . . 8
⊢ (𝜑 → ∀𝑥 ∈ (𝐴[,]𝐵)(𝐹‘𝑥) ∈ ℝ) | 
| 29 | 27, 28, 24 | rspcdva 2873 | 
. . . . . . 7
⊢ (𝜑 → (𝐹‘𝐴) ∈ ℝ) | 
| 30 | 29 | renegcld 8406 | 
. . . . . 6
⊢ (𝜑 → -(𝐹‘𝐴) ∈ ℝ) | 
| 31 | 8, 19, 25, 30 | fvmptd3 5655 | 
. . . . 5
⊢ (𝜑 → ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝐴) = -(𝐹‘𝐴)) | 
| 32 |   | ivthdec.9 | 
. . . . . . 7
⊢ (𝜑 → ((𝐹‘𝐵) < 𝑈 ∧ 𝑈 < (𝐹‘𝐴))) | 
| 33 | 32 | simprd 114 | 
. . . . . 6
⊢ (𝜑 → 𝑈 < (𝐹‘𝐴)) | 
| 34 | 3, 29 | ltnegd 8550 | 
. . . . . 6
⊢ (𝜑 → (𝑈 < (𝐹‘𝐴) ↔ -(𝐹‘𝐴) < -𝑈)) | 
| 35 | 33, 34 | mpbid 147 | 
. . . . 5
⊢ (𝜑 → -(𝐹‘𝐴) < -𝑈) | 
| 36 | 31, 35 | eqbrtrd 4055 | 
. . . 4
⊢ (𝜑 → ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝐴) < -𝑈) | 
| 37 | 32 | simpld 112 | 
. . . . . 6
⊢ (𝜑 → (𝐹‘𝐵) < 𝑈) | 
| 38 |   | fveq2 5558 | 
. . . . . . . . 9
⊢ (𝑥 = 𝐵 → (𝐹‘𝑥) = (𝐹‘𝐵)) | 
| 39 | 38 | eleq1d 2265 | 
. . . . . . . 8
⊢ (𝑥 = 𝐵 → ((𝐹‘𝑥) ∈ ℝ ↔ (𝐹‘𝐵) ∈ ℝ)) | 
| 40 |   | ubicc2 10060 | 
. . . . . . . . 9
⊢ ((𝐴 ∈ ℝ*
∧ 𝐵 ∈
ℝ* ∧ 𝐴
≤ 𝐵) → 𝐵 ∈ (𝐴[,]𝐵)) | 
| 41 | 20, 21, 22, 40 | syl3anc 1249 | 
. . . . . . . 8
⊢ (𝜑 → 𝐵 ∈ (𝐴[,]𝐵)) | 
| 42 | 39, 28, 41 | rspcdva 2873 | 
. . . . . . 7
⊢ (𝜑 → (𝐹‘𝐵) ∈ ℝ) | 
| 43 | 42, 3 | ltnegd 8550 | 
. . . . . 6
⊢ (𝜑 → ((𝐹‘𝐵) < 𝑈 ↔ -𝑈 < -(𝐹‘𝐵))) | 
| 44 | 37, 43 | mpbid 147 | 
. . . . 5
⊢ (𝜑 → -𝑈 < -(𝐹‘𝐵)) | 
| 45 |   | fveq2 5558 | 
. . . . . . 7
⊢ (𝑤 = 𝐵 → (𝐹‘𝑤) = (𝐹‘𝐵)) | 
| 46 | 45 | negeqd 8221 | 
. . . . . 6
⊢ (𝑤 = 𝐵 → -(𝐹‘𝑤) = -(𝐹‘𝐵)) | 
| 47 | 6, 41 | sseldd 3184 | 
. . . . . 6
⊢ (𝜑 → 𝐵 ∈ 𝐷) | 
| 48 | 42 | renegcld 8406 | 
. . . . . 6
⊢ (𝜑 → -(𝐹‘𝐵) ∈ ℝ) | 
| 49 | 8, 46, 47, 48 | fvmptd3 5655 | 
. . . . 5
⊢ (𝜑 → ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝐵) = -(𝐹‘𝐵)) | 
| 50 | 44, 49 | breqtrrd 4061 | 
. . . 4
⊢ (𝜑 → -𝑈 < ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝐵)) | 
| 51 | 36, 50 | jca 306 | 
. . 3
⊢ (𝜑 → (((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝐴) < -𝑈 ∧ -𝑈 < ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝐵))) | 
| 52 |   | ivthdec.i | 
. . . . 5
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → (𝐹‘𝑦) < (𝐹‘𝑥)) | 
| 53 |   | fveq2 5558 | 
. . . . . . . 8
⊢ (𝑥 = 𝑦 → (𝐹‘𝑥) = (𝐹‘𝑦)) | 
| 54 | 53 | eleq1d 2265 | 
. . . . . . 7
⊢ (𝑥 = 𝑦 → ((𝐹‘𝑥) ∈ ℝ ↔ (𝐹‘𝑦) ∈ ℝ)) | 
| 55 |   | simpll 527 | 
. . . . . . . 8
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → 𝜑) | 
| 56 | 55, 28 | syl 14 | 
. . . . . . 7
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → ∀𝑥 ∈ (𝐴[,]𝐵)(𝐹‘𝑥) ∈ ℝ) | 
| 57 |   | simprl 529 | 
. . . . . . 7
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → 𝑦 ∈ (𝐴[,]𝐵)) | 
| 58 | 54, 56, 57 | rspcdva 2873 | 
. . . . . 6
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → (𝐹‘𝑦) ∈ ℝ) | 
| 59 | 14 | adantr 276 | 
. . . . . 6
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → (𝐹‘𝑥) ∈ ℝ) | 
| 60 | 58, 59 | ltnegd 8550 | 
. . . . 5
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → ((𝐹‘𝑦) < (𝐹‘𝑥) ↔ -(𝐹‘𝑥) < -(𝐹‘𝑦))) | 
| 61 | 52, 60 | mpbid 147 | 
. . . 4
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → -(𝐹‘𝑥) < -(𝐹‘𝑦)) | 
| 62 | 13 | adantr 276 | 
. . . . 5
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → 𝑥 ∈ 𝐷) | 
| 63 | 15 | adantr 276 | 
. . . . 5
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → -(𝐹‘𝑥) ∈ ℝ) | 
| 64 | 8, 12, 62, 63 | fvmptd3 5655 | 
. . . 4
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝑥) = -(𝐹‘𝑥)) | 
| 65 |   | fveq2 5558 | 
. . . . . 6
⊢ (𝑤 = 𝑦 → (𝐹‘𝑤) = (𝐹‘𝑦)) | 
| 66 | 65 | negeqd 8221 | 
. . . . 5
⊢ (𝑤 = 𝑦 → -(𝐹‘𝑤) = -(𝐹‘𝑦)) | 
| 67 | 6 | sseld 3182 | 
. . . . . 6
⊢ (𝜑 → (𝑦 ∈ (𝐴[,]𝐵) → 𝑦 ∈ 𝐷)) | 
| 68 | 55, 57, 67 | sylc 62 | 
. . . . 5
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → 𝑦 ∈ 𝐷) | 
| 69 | 58 | renegcld 8406 | 
. . . . 5
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → -(𝐹‘𝑦) ∈ ℝ) | 
| 70 | 8, 66, 68, 69 | fvmptd3 5655 | 
. . . 4
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝑦) = -(𝐹‘𝑦)) | 
| 71 | 61, 64, 70 | 3brtr4d 4065 | 
. . 3
⊢ (((𝜑 ∧ 𝑥 ∈ (𝐴[,]𝐵)) ∧ (𝑦 ∈ (𝐴[,]𝐵) ∧ 𝑥 < 𝑦)) → ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝑥) < ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝑦)) | 
| 72 | 1, 2, 4, 5, 6, 10,
17, 51, 71 | ivthinc 14879 | 
. 2
⊢ (𝜑 → ∃𝑐 ∈ (𝐴(,)𝐵)((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝑐) = -𝑈) | 
| 73 |   | fveq2 5558 | 
. . . . . . 7
⊢ (𝑤 = 𝑐 → (𝐹‘𝑤) = (𝐹‘𝑐)) | 
| 74 | 73 | negeqd 8221 | 
. . . . . 6
⊢ (𝑤 = 𝑐 → -(𝐹‘𝑤) = -(𝐹‘𝑐)) | 
| 75 |   | ioossicc 10034 | 
. . . . . . . 8
⊢ (𝐴(,)𝐵) ⊆ (𝐴[,]𝐵) | 
| 76 | 75, 6 | sstrid 3194 | 
. . . . . . 7
⊢ (𝜑 → (𝐴(,)𝐵) ⊆ 𝐷) | 
| 77 | 76 | sselda 3183 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑐 ∈ (𝐴(,)𝐵)) → 𝑐 ∈ 𝐷) | 
| 78 |   | fveq2 5558 | 
. . . . . . . . 9
⊢ (𝑥 = 𝑐 → (𝐹‘𝑥) = (𝐹‘𝑐)) | 
| 79 | 78 | eleq1d 2265 | 
. . . . . . . 8
⊢ (𝑥 = 𝑐 → ((𝐹‘𝑥) ∈ ℝ ↔ (𝐹‘𝑐) ∈ ℝ)) | 
| 80 | 28 | adantr 276 | 
. . . . . . . 8
⊢ ((𝜑 ∧ 𝑐 ∈ (𝐴(,)𝐵)) → ∀𝑥 ∈ (𝐴[,]𝐵)(𝐹‘𝑥) ∈ ℝ) | 
| 81 | 75 | sseli 3179 | 
. . . . . . . . 9
⊢ (𝑐 ∈ (𝐴(,)𝐵) → 𝑐 ∈ (𝐴[,]𝐵)) | 
| 82 | 81 | adantl 277 | 
. . . . . . . 8
⊢ ((𝜑 ∧ 𝑐 ∈ (𝐴(,)𝐵)) → 𝑐 ∈ (𝐴[,]𝐵)) | 
| 83 | 79, 80, 82 | rspcdva 2873 | 
. . . . . . 7
⊢ ((𝜑 ∧ 𝑐 ∈ (𝐴(,)𝐵)) → (𝐹‘𝑐) ∈ ℝ) | 
| 84 | 83 | renegcld 8406 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑐 ∈ (𝐴(,)𝐵)) → -(𝐹‘𝑐) ∈ ℝ) | 
| 85 | 8, 74, 77, 84 | fvmptd3 5655 | 
. . . . 5
⊢ ((𝜑 ∧ 𝑐 ∈ (𝐴(,)𝐵)) → ((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝑐) = -(𝐹‘𝑐)) | 
| 86 | 85 | eqeq1d 2205 | 
. . . 4
⊢ ((𝜑 ∧ 𝑐 ∈ (𝐴(,)𝐵)) → (((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝑐) = -𝑈 ↔ -(𝐹‘𝑐) = -𝑈)) | 
| 87 |   | cncff 14813 | 
. . . . . . . 8
⊢ (𝐹 ∈ (𝐷–cn→ℂ) → 𝐹:𝐷⟶ℂ) | 
| 88 | 7, 87 | syl 14 | 
. . . . . . 7
⊢ (𝜑 → 𝐹:𝐷⟶ℂ) | 
| 89 | 88 | ffvelcdmda 5697 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑐 ∈ 𝐷) → (𝐹‘𝑐) ∈ ℂ) | 
| 90 | 77, 89 | syldan 282 | 
. . . . 5
⊢ ((𝜑 ∧ 𝑐 ∈ (𝐴(,)𝐵)) → (𝐹‘𝑐) ∈ ℂ) | 
| 91 | 3 | recnd 8055 | 
. . . . . 6
⊢ (𝜑 → 𝑈 ∈ ℂ) | 
| 92 | 91 | adantr 276 | 
. . . . 5
⊢ ((𝜑 ∧ 𝑐 ∈ (𝐴(,)𝐵)) → 𝑈 ∈ ℂ) | 
| 93 | 90, 92 | neg11ad 8333 | 
. . . 4
⊢ ((𝜑 ∧ 𝑐 ∈ (𝐴(,)𝐵)) → (-(𝐹‘𝑐) = -𝑈 ↔ (𝐹‘𝑐) = 𝑈)) | 
| 94 | 86, 93 | bitrd 188 | 
. . 3
⊢ ((𝜑 ∧ 𝑐 ∈ (𝐴(,)𝐵)) → (((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝑐) = -𝑈 ↔ (𝐹‘𝑐) = 𝑈)) | 
| 95 | 94 | rexbidva 2494 | 
. 2
⊢ (𝜑 → (∃𝑐 ∈ (𝐴(,)𝐵)((𝑤 ∈ 𝐷 ↦ -(𝐹‘𝑤))‘𝑐) = -𝑈 ↔ ∃𝑐 ∈ (𝐴(,)𝐵)(𝐹‘𝑐) = 𝑈)) | 
| 96 | 72, 95 | mpbid 147 | 
1
⊢ (𝜑 → ∃𝑐 ∈ (𝐴(,)𝐵)(𝐹‘𝑐) = 𝑈) |