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Type | Label | Description |
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Statement | ||
Theorem | dnibndlem12 33001* | Lemma for dnibnd 33003. (Contributed by Asger C. Ipsen, 4-Apr-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) & ⊢ (𝜑 → ((⌊‘(𝐴 + (1 / 2))) + 2) ≤ (⌊‘(𝐵 + (1 / 2)))) ⇒ ⊢ (𝜑 → (abs‘((𝑇‘𝐵) − (𝑇‘𝐴))) ≤ (abs‘(𝐵 − 𝐴))) | ||
Theorem | dnibndlem13 33002* | Lemma for dnibnd 33003. (Contributed by Asger C. Ipsen, 4-Apr-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) & ⊢ (𝜑 → (⌊‘(𝐴 + (1 / 2))) ≤ (⌊‘(𝐵 + (1 / 2)))) ⇒ ⊢ (𝜑 → (abs‘((𝑇‘𝐵) − (𝑇‘𝐴))) ≤ (abs‘(𝐵 − 𝐴))) | ||
Theorem | dnibnd 33003* | The "distance to nearest integer" function is 1-Lipschitz continuous, i.e., is a short map. (Contributed by Asger C. Ipsen, 4-Apr-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) ⇒ ⊢ (𝜑 → (abs‘((𝑇‘𝐵) − (𝑇‘𝐴))) ≤ (abs‘(𝐵 − 𝐴))) | ||
Theorem | dnicn 33004 | The "distance to nearest integer" function is continuous. (Contributed by Asger C. Ipsen, 4-Apr-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) ⇒ ⊢ 𝑇 ∈ (ℝ–cn→ℝ) | ||
Theorem | knoppcnlem1 33005* | Lemma for knoppcn 33016. (Contributed by Asger C. Ipsen, 4-Apr-2021.) |
⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝑀 ∈ ℕ0) ⇒ ⊢ (𝜑 → ((𝐹‘𝐴)‘𝑀) = ((𝐶↑𝑀) · (𝑇‘(((2 · 𝑁)↑𝑀) · 𝐴)))) | ||
Theorem | knoppcnlem2 33006* | Lemma for knoppcn 33016. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝑀 ∈ ℕ0) ⇒ ⊢ (𝜑 → ((𝐶↑𝑀) · (𝑇‘(((2 · 𝑁)↑𝑀) · 𝐴))) ∈ ℝ) | ||
Theorem | knoppcnlem3 33007* | Lemma for knoppcn 33016. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝑀 ∈ ℕ0) ⇒ ⊢ (𝜑 → ((𝐹‘𝐴)‘𝑀) ∈ ℝ) | ||
Theorem | knoppcnlem4 33008* | Lemma for knoppcn 33016. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝑀 ∈ ℕ0) ⇒ ⊢ (𝜑 → (abs‘((𝐹‘𝐴)‘𝑀)) ≤ ((𝑚 ∈ ℕ0 ↦ ((abs‘𝐶)↑𝑚))‘𝑀)) | ||
Theorem | knoppcnlem5 33009* | Lemma for knoppcn 33016. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) ⇒ ⊢ (𝜑 → (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹‘𝑧)‘𝑚))):ℕ0⟶(ℂ ↑𝑚 ℝ)) | ||
Theorem | knoppcnlem6 33010* | Lemma for knoppcn 33016. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → (abs‘𝐶) < 1) ⇒ ⊢ (𝜑 → seq0( ∘𝑓 + , (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹‘𝑧)‘𝑚)))) ∈ dom (⇝𝑢‘ℝ)) | ||
Theorem | knoppcnlem7 33011* | Lemma for knoppcn 33016. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → 𝑀 ∈ ℕ0) ⇒ ⊢ (𝜑 → (seq0( ∘𝑓 + , (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹‘𝑧)‘𝑚))))‘𝑀) = (𝑤 ∈ ℝ ↦ (seq0( + , (𝐹‘𝑤))‘𝑀))) | ||
Theorem | knoppcnlem8 33012* | Lemma for knoppcn 33016. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) ⇒ ⊢ (𝜑 → seq0( ∘𝑓 + , (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹‘𝑧)‘𝑚)))):ℕ0⟶(ℂ ↑𝑚 ℝ)) | ||
Theorem | knoppcnlem9 33013* | Lemma for knoppcn 33016. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → (abs‘𝐶) < 1) ⇒ ⊢ (𝜑 → seq0( ∘𝑓 + , (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹‘𝑧)‘𝑚))))(⇝𝑢‘ℝ)𝑊) | ||
Theorem | knoppcnlem10 33014* | Lemma for knoppcn 33016. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → 𝑀 ∈ ℕ0) ⇒ ⊢ (𝜑 → (𝑧 ∈ ℝ ↦ ((𝐹‘𝑧)‘𝑀)) ∈ ((topGen‘ran (,)) Cn (TopOpen‘ℂfld))) | ||
Theorem | knoppcnlem11 33015* | Lemma for knoppcn 33016. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) ⇒ ⊢ (𝜑 → seq0( ∘𝑓 + , (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹‘𝑧)‘𝑚)))):ℕ0⟶(ℝ–cn→ℂ)) | ||
Theorem | knoppcn 33016* | The continuous nowhere differentiable function 𝑊 ( Knopp, K. (1918). Math. Z. 2, 1-26 ) is, in fact, continuous. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → (abs‘𝐶) < 1) ⇒ ⊢ (𝜑 → 𝑊 ∈ (ℝ–cn→ℂ)) | ||
Theorem | knoppcld 33017* | Closure theorem for Knopp's function. (Contributed by Asger C. Ipsen, 26-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → (abs‘𝐶) < 1) ⇒ ⊢ (𝜑 → (𝑊‘𝐴) ∈ ℂ) | ||
Theorem | unblimceq0lem 33018* | Lemma for unblimceq0 33019. (Contributed by Asger C. Ipsen, 12-May-2021.) |
⊢ (𝜑 → 𝑆 ⊆ ℂ) & ⊢ (𝜑 → 𝐹:𝑆⟶ℂ) & ⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → ∀𝑏 ∈ ℝ+ ∀𝑑 ∈ ℝ+ ∃𝑥 ∈ 𝑆 ((abs‘(𝑥 − 𝐴)) < 𝑑 ∧ 𝑏 ≤ (abs‘(𝐹‘𝑥)))) ⇒ ⊢ (𝜑 → ∀𝑐 ∈ ℝ+ ∀𝑑 ∈ ℝ+ ∃𝑦 ∈ 𝑆 (𝑦 ≠ 𝐴 ∧ (abs‘(𝑦 − 𝐴)) < 𝑑 ∧ 𝑐 ≤ (abs‘(𝐹‘𝑦)))) | ||
Theorem | unblimceq0 33019* | If 𝐹 is unbounded near 𝐴 it has no limit at 𝐴. (Contributed by Asger C. Ipsen, 12-May-2021.) |
⊢ (𝜑 → 𝑆 ⊆ ℂ) & ⊢ (𝜑 → 𝐹:𝑆⟶ℂ) & ⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → ∀𝑏 ∈ ℝ+ ∀𝑑 ∈ ℝ+ ∃𝑥 ∈ 𝑆 ((abs‘(𝑥 − 𝐴)) < 𝑑 ∧ 𝑏 ≤ (abs‘(𝐹‘𝑥)))) ⇒ ⊢ (𝜑 → (𝐹 limℂ 𝐴) = ∅) | ||
Theorem | unbdqndv1 33020* | If the difference quotient (((𝐹‘𝑧) − (𝐹‘𝐴)) / (𝑧 − 𝐴)) is unbounded near 𝐴 then 𝐹 is not differentiable at 𝐴. (Contributed by Asger C. Ipsen, 12-May-2021.) |
⊢ 𝐺 = (𝑧 ∈ (𝑋 ∖ {𝐴}) ↦ (((𝐹‘𝑧) − (𝐹‘𝐴)) / (𝑧 − 𝐴))) & ⊢ (𝜑 → 𝑆 ⊆ ℂ) & ⊢ (𝜑 → 𝑋 ⊆ 𝑆) & ⊢ (𝜑 → 𝐹:𝑋⟶ℂ) & ⊢ (𝜑 → ∀𝑏 ∈ ℝ+ ∀𝑑 ∈ ℝ+ ∃𝑥 ∈ (𝑋 ∖ {𝐴})((abs‘(𝑥 − 𝐴)) < 𝑑 ∧ 𝑏 ≤ (abs‘(𝐺‘𝑥)))) ⇒ ⊢ (𝜑 → ¬ 𝐴 ∈ dom (𝑆 D 𝐹)) | ||
Theorem | unbdqndv2lem1 33021 | Lemma for unbdqndv2 33023. (Contributed by Asger C. Ipsen, 12-May-2021.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) & ⊢ (𝜑 → 𝐶 ∈ ℂ) & ⊢ (𝜑 → 𝐷 ∈ ℂ) & ⊢ (𝜑 → 𝐸 ∈ ℝ+) & ⊢ (𝜑 → 𝐷 ≠ 0) & ⊢ (𝜑 → (2 · 𝐸) ≤ (abs‘((𝐴 − 𝐵) / 𝐷))) ⇒ ⊢ (𝜑 → ((𝐸 · (abs‘𝐷)) ≤ (abs‘(𝐴 − 𝐶)) ∨ (𝐸 · (abs‘𝐷)) ≤ (abs‘(𝐵 − 𝐶)))) | ||
Theorem | unbdqndv2lem2 33022* | Lemma for unbdqndv2 33023. (Contributed by Asger C. Ipsen, 12-May-2021.) |
⊢ 𝐺 = (𝑧 ∈ (𝑋 ∖ {𝐴}) ↦ (((𝐹‘𝑧) − (𝐹‘𝐴)) / (𝑧 − 𝐴))) & ⊢ 𝑊 = if((𝐵 · (𝑉 − 𝑈)) ≤ (abs‘((𝐹‘𝑈) − (𝐹‘𝐴))), 𝑈, 𝑉) & ⊢ (𝜑 → 𝑋 ⊆ ℝ) & ⊢ (𝜑 → 𝐹:𝑋⟶ℂ) & ⊢ (𝜑 → 𝐴 ∈ 𝑋) & ⊢ (𝜑 → 𝐵 ∈ ℝ+) & ⊢ (𝜑 → 𝐷 ∈ ℝ+) & ⊢ (𝜑 → 𝑈 ∈ 𝑋) & ⊢ (𝜑 → 𝑉 ∈ 𝑋) & ⊢ (𝜑 → 𝑈 ≠ 𝑉) & ⊢ (𝜑 → 𝑈 ≤ 𝐴) & ⊢ (𝜑 → 𝐴 ≤ 𝑉) & ⊢ (𝜑 → (𝑉 − 𝑈) < 𝐷) & ⊢ (𝜑 → (2 · 𝐵) ≤ ((abs‘((𝐹‘𝑉) − (𝐹‘𝑈))) / (𝑉 − 𝑈))) ⇒ ⊢ (𝜑 → (𝑊 ∈ (𝑋 ∖ {𝐴}) ∧ ((abs‘(𝑊 − 𝐴)) < 𝐷 ∧ 𝐵 ≤ (abs‘(𝐺‘𝑊))))) | ||
Theorem | unbdqndv2 33023* | Variant of unbdqndv1 33020 with the hypothesis that (((𝐹‘𝑦) − (𝐹‘𝑥)) / (𝑦 − 𝑥)) is unbounded where 𝑥 ≤ 𝐴 and 𝐴 ≤ 𝑦. (Contributed by Asger C. Ipsen, 12-May-2021.) |
⊢ (𝜑 → 𝑋 ⊆ ℝ) & ⊢ (𝜑 → 𝐹:𝑋⟶ℂ) & ⊢ (𝜑 → ∀𝑏 ∈ ℝ+ ∀𝑑 ∈ ℝ+ ∃𝑥 ∈ 𝑋 ∃𝑦 ∈ 𝑋 ((𝑥 ≤ 𝐴 ∧ 𝐴 ≤ 𝑦) ∧ ((𝑦 − 𝑥) < 𝑑 ∧ 𝑥 ≠ 𝑦) ∧ 𝑏 ≤ ((abs‘((𝐹‘𝑦) − (𝐹‘𝑥))) / (𝑦 − 𝑥)))) ⇒ ⊢ (𝜑 → ¬ 𝐴 ∈ dom (ℝ D 𝐹)) | ||
Theorem | knoppndvlem1 33024 | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 15-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐽 ∈ ℤ) & ⊢ (𝜑 → 𝑀 ∈ ℤ) ⇒ ⊢ (𝜑 → ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀) ∈ ℝ) | ||
Theorem | knoppndvlem2 33025 | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 15-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐼 ∈ ℤ) & ⊢ (𝜑 → 𝐽 ∈ ℤ) & ⊢ (𝜑 → 𝑀 ∈ ℤ) & ⊢ (𝜑 → 𝐽 < 𝐼) ⇒ ⊢ (𝜑 → (((2 · 𝑁)↑𝐼) · ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀)) ∈ ℤ) | ||
Theorem | knoppndvlem3 33026 | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 15-Jun-2021.) |
⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) ⇒ ⊢ (𝜑 → (𝐶 ∈ ℝ ∧ (abs‘𝐶) < 1)) | ||
Theorem | knoppndvlem4 33027* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 15-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝑁 ∈ ℕ) ⇒ ⊢ (𝜑 → seq0( + , (𝐹‘𝐴)) ⇝ (𝑊‘𝐴)) | ||
Theorem | knoppndvlem5 33028* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 15-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐶 ∈ ℝ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) ⇒ ⊢ (𝜑 → Σ𝑖 ∈ (0...𝐽)((𝐹‘𝐴)‘𝑖) ∈ ℝ) | ||
Theorem | knoppndvlem6 33029* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 15-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ 𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝑀 ∈ ℤ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) ⇒ ⊢ (𝜑 → (𝑊‘𝐴) = Σ𝑖 ∈ (0...𝐽)((𝐹‘𝐴)‘𝑖)) | ||
Theorem | knoppndvlem7 33030* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 15-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝑀 ∈ ℤ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) ⇒ ⊢ (𝜑 → ((𝐹‘𝐴)‘𝐽) = ((𝐶↑𝐽) · (𝑇‘(𝑀 / 2)))) | ||
Theorem | knoppndvlem8 33031* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 15-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝑀 ∈ ℤ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 2 ∥ 𝑀) ⇒ ⊢ (𝜑 → ((𝐹‘𝐴)‘𝐽) = 0) | ||
Theorem | knoppndvlem9 33032* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 15-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝑀 ∈ ℤ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → ¬ 2 ∥ 𝑀) ⇒ ⊢ (𝜑 → ((𝐹‘𝐴)‘𝐽) = ((𝐶↑𝐽) / 2)) | ||
Theorem | knoppndvlem10 33033* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 15-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀) & ⊢ 𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑀 + 1)) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝑀 ∈ ℤ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) ⇒ ⊢ (𝜑 → (abs‘(((𝐹‘𝐵)‘𝐽) − ((𝐹‘𝐴)‘𝐽))) = (((abs‘𝐶)↑𝐽) / 2)) | ||
Theorem | knoppndvlem11 33034* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 28-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝑁 ∈ ℕ) ⇒ ⊢ (𝜑 → (abs‘(Σ𝑖 ∈ (0...(𝐽 − 1))((𝐹‘𝐵)‘𝑖) − Σ𝑖 ∈ (0...(𝐽 − 1))((𝐹‘𝐴)‘𝑖))) ≤ ((abs‘(𝐵 − 𝐴)) · Σ𝑖 ∈ (0...(𝐽 − 1))(((2 · 𝑁) · (abs‘𝐶))↑𝑖))) | ||
Theorem | knoppndvlem12 33035 | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 29-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 1 < (𝑁 · (abs‘𝐶))) ⇒ ⊢ (𝜑 → (((2 · 𝑁) · (abs‘𝐶)) ≠ 1 ∧ 1 < (((2 · 𝑁) · (abs‘𝐶)) − 1))) | ||
Theorem | knoppndvlem13 33036 | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 1-Jul-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.) |
⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 1 < (𝑁 · (abs‘𝐶))) ⇒ ⊢ (𝜑 → 𝐶 ≠ 0) | ||
Theorem | knoppndvlem14 33037* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 1-Jul-2021.) (Revised by Asger C. Ipsen, 7-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀) & ⊢ 𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑀 + 1)) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝑀 ∈ ℤ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 1 < (𝑁 · (abs‘𝐶))) ⇒ ⊢ (𝜑 → (abs‘(Σ𝑖 ∈ (0...(𝐽 − 1))((𝐹‘𝐵)‘𝑖) − Σ𝑖 ∈ (0...(𝐽 − 1))((𝐹‘𝐴)‘𝑖))) ≤ ((((abs‘𝐶)↑𝐽) / 2) · (1 / (((2 · 𝑁) · (abs‘𝐶)) − 1)))) | ||
Theorem | knoppndvlem15 33038* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 6-Jul-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ 𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀) & ⊢ 𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑀 + 1)) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝑀 ∈ ℤ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 1 < (𝑁 · (abs‘𝐶))) ⇒ ⊢ (𝜑 → ((((abs‘𝐶)↑𝐽) / 2) · (1 − (1 / (((2 · 𝑁) · (abs‘𝐶)) − 1)))) ≤ (abs‘((𝑊‘𝐵) − (𝑊‘𝐴)))) | ||
Theorem | knoppndvlem16 33039 | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 19-Jul-2021.) |
⊢ 𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀) & ⊢ 𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑀 + 1)) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝑀 ∈ ℤ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) ⇒ ⊢ (𝜑 → (𝐵 − 𝐴) = (((2 · 𝑁)↑-𝐽) / 2)) | ||
Theorem | knoppndvlem17 33040* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 12-Aug-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ 𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀) & ⊢ 𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑀 + 1)) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝑀 ∈ ℤ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 1 < (𝑁 · (abs‘𝐶))) ⇒ ⊢ (𝜑 → ((((2 · 𝑁) · (abs‘𝐶))↑𝐽) · (1 − (1 / (((2 · 𝑁) · (abs‘𝐶)) − 1)))) ≤ ((abs‘((𝑊‘𝐵) − (𝑊‘𝐴))) / (𝐵 − 𝐴))) | ||
Theorem | knoppndvlem18 33041* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 14-Aug-2021.) |
⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐷 ∈ ℝ+) & ⊢ (𝜑 → 𝐸 ∈ ℝ+) & ⊢ (𝜑 → 𝐺 ∈ ℝ+) & ⊢ (𝜑 → 1 < (𝑁 · (abs‘𝐶))) ⇒ ⊢ (𝜑 → ∃𝑗 ∈ ℕ0 ((((2 · 𝑁)↑-𝑗) / 2) < 𝐷 ∧ 𝐸 ≤ ((((2 · 𝑁) · (abs‘𝐶))↑𝑗) · 𝐺))) | ||
Theorem | knoppndvlem19 33042* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 17-Aug-2021.) |
⊢ 𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑚) & ⊢ 𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑚 + 1)) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝐻 ∈ ℝ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) ⇒ ⊢ (𝜑 → ∃𝑚 ∈ ℤ (𝐴 ≤ 𝐻 ∧ 𝐻 ≤ 𝐵)) | ||
Theorem | knoppndvlem20 33043 | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 18-Aug-2021.) |
⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 1 < (𝑁 · (abs‘𝐶))) ⇒ ⊢ (𝜑 → (1 − (1 / (((2 · 𝑁) · (abs‘𝐶)) − 1))) ∈ ℝ+) | ||
Theorem | knoppndvlem21 33044* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 18-Aug-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ 𝐺 = (1 − (1 / (((2 · 𝑁) · (abs‘𝐶)) − 1))) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝐷 ∈ ℝ+) & ⊢ (𝜑 → 𝐸 ∈ ℝ+) & ⊢ (𝜑 → 𝐻 ∈ ℝ) & ⊢ (𝜑 → 𝐽 ∈ ℕ0) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 1 < (𝑁 · (abs‘𝐶))) & ⊢ (𝜑 → (((2 · 𝑁)↑-𝐽) / 2) < 𝐷) & ⊢ (𝜑 → 𝐸 ≤ ((((2 · 𝑁) · (abs‘𝐶))↑𝐽) · 𝐺)) ⇒ ⊢ (𝜑 → ∃𝑎 ∈ ℝ ∃𝑏 ∈ ℝ ((𝑎 ≤ 𝐻 ∧ 𝐻 ≤ 𝑏) ∧ ((𝑏 − 𝑎) < 𝐷 ∧ 𝑎 ≠ 𝑏) ∧ 𝐸 ≤ ((abs‘((𝑊‘𝑏) − (𝑊‘𝑎))) / (𝑏 − 𝑎)))) | ||
Theorem | knoppndvlem22 33045* | Lemma for knoppndv 33046. (Contributed by Asger C. Ipsen, 19-Aug-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝐷 ∈ ℝ+) & ⊢ (𝜑 → 𝐸 ∈ ℝ+) & ⊢ (𝜑 → 𝐻 ∈ ℝ) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 1 < (𝑁 · (abs‘𝐶))) ⇒ ⊢ (𝜑 → ∃𝑎 ∈ ℝ ∃𝑏 ∈ ℝ ((𝑎 ≤ 𝐻 ∧ 𝐻 ≤ 𝑏) ∧ ((𝑏 − 𝑎) < 𝐷 ∧ 𝑎 ≠ 𝑏) ∧ 𝐸 ≤ ((abs‘((𝑊‘𝑏) − (𝑊‘𝑎))) / (𝑏 − 𝑎)))) | ||
Theorem | knoppndv 33046* | The continuous nowhere differentiable function 𝑊 ( Knopp, K. (1918). Math. Z. 2, 1-26 ) is, in fact, nowhere differentiable. (Contributed by Asger C. Ipsen, 19-Aug-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 1 < (𝑁 · (abs‘𝐶))) ⇒ ⊢ (𝜑 → dom (ℝ D 𝑊) = ∅) | ||
Theorem | knoppf 33047* | Knopp's function is a function. (Contributed by Asger C. Ipsen, 25-Aug-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) & ⊢ (𝜑 → 𝑁 ∈ ℕ) ⇒ ⊢ (𝜑 → 𝑊:ℝ⟶ℝ) | ||
Theorem | knoppcn2 33048* | Variant of knoppcn 33016 with different codomain. (Contributed by Asger C. Ipsen, 25-Aug-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶↑𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) & ⊢ (𝜑 → 𝑁 ∈ ℕ) & ⊢ (𝜑 → 𝐶 ∈ (-1(,)1)) ⇒ ⊢ (𝜑 → 𝑊 ∈ (ℝ–cn→ℝ)) | ||
Theorem | cnndvlem1 33049* | Lemma for cnndv 33051. (Contributed by Asger C. Ipsen, 25-Aug-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ (((1 / 2)↑𝑛) · (𝑇‘(((2 · 3)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) ⇒ ⊢ (𝑊 ∈ (ℝ–cn→ℝ) ∧ dom (ℝ D 𝑊) = ∅) | ||
Theorem | cnndvlem2 33050* | Lemma for cnndv 33051. (Contributed by Asger C. Ipsen, 26-Aug-2021.) |
⊢ 𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥))) & ⊢ 𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ (((1 / 2)↑𝑛) · (𝑇‘(((2 · 3)↑𝑛) · 𝑦))))) & ⊢ 𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹‘𝑤)‘𝑖)) ⇒ ⊢ ∃𝑓(𝑓 ∈ (ℝ–cn→ℝ) ∧ dom (ℝ D 𝑓) = ∅) | ||
Theorem | cnndv 33051 | There exists a continuous nowhere differentiable function. The result follows directly from knoppcn 33016 and knoppndv 33046. (Contributed by Asger C. Ipsen, 26-Aug-2021.) |
⊢ ∃𝑓(𝑓 ∈ (ℝ–cn→ℝ) ∧ dom (ℝ D 𝑓) = ∅) | ||
In this mathbox, we try to respect the ordering of the sections of the main part. There are strengthenings of theorems of the main part, as well as work on reducing axiom dependencies. | ||
Miscellaneous utility theorems of propositional calculus. | ||
In this section, we prove a few rules of inference derived from modus ponens ax-mp 5, and which do not depend on any other axioms. | ||
Theorem | bj-mp2c 33052 | A double modus ponens inference. Inference associated with mpd 15. (Contributed by BJ, 24-Sep-2019.) |
⊢ 𝜑 & ⊢ (𝜑 → 𝜓) & ⊢ (𝜑 → (𝜓 → 𝜒)) ⇒ ⊢ 𝜒 | ||
Theorem | bj-mp2d 33053 | A double modus ponens inference. Inference associated with mpcom 38. (Contributed by BJ, 24-Sep-2019.) |
⊢ 𝜑 & ⊢ (𝜑 → 𝜓) & ⊢ (𝜓 → (𝜑 → 𝜒)) ⇒ ⊢ 𝜒 | ||
In this section, we prove a syntactic theorem (bj-0 33054) asserting that some formula is well-formed. Then, we use this syntactic theorem to shorten the proof of a "usual" theorem (bj-1 33055) and explain in the comment of that theorem why this phenomenon is unusual. | ||
Theorem | bj-0 33054 | A syntactic theorem. See the section comment and the comment of bj-1 33055. The full proof (that is, with the syntactic, non-essential steps) does not appear on this webpage. It has five steps and reads $= wph wps wi wch wi $. The only other syntactic theorems in the main part of set.mm are wel 2165 and weq 2061. (Contributed by BJ, 24-Sep-2019.) (Proof modification is discouraged.) (New usage is discouraged.) |
wff ((𝜑 → 𝜓) → 𝜒) | ||
Theorem | bj-1 33055 |
In this proof, the use of the syntactic theorem bj-0 33054
allows to reduce
the total length by one (non-essential) step. See also the section
comment and the comment of bj-0 33054. Since bj-0 33054
is used in a
non-essential step, this use does not appear on this webpage (but the
present theorem appears on the webpage for bj-0 33054
as a theorem referencing
it). The full proof reads $= wph wps wch bj-0 id $. (while, without
using bj-0 33054, it would read $= wph wps wi wch wi id $.).
Now we explain why syntactic theorems are not useful in set.mm. Suppose that the syntactic theorem thm-0 proves that PHI is a well-formed formula, and that thm-0 is used to shorten the proof of thm-1. Assume that PHI does have proper non-atomic subformulas (which is not the case of the formula proved by weq 2061 or wel 2165). Then, the proof of thm-1 does not construct all the proper non-atomic subformulas of PHI (if it did, then using thm-0 would not shorten it). Therefore, thm-1 is a special instance of a more general theorem with essentially the same proof. In the present case, bj-1 33055 is a special instance of id 22. (Contributed by BJ, 24-Sep-2019.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (((𝜑 → 𝜓) → 𝜒) → ((𝜑 → 𝜓) → 𝜒)) | ||
Theorem | bj-a1k 33056 | Weakening of ax-1 6. This shortens the proofs of dfwe2 7242 (937>925), ordunisuc2 7305 (789>777), r111 8915 (558>545), smo11 7727 (1176>1164). (Contributed by BJ, 11-Aug-2020.) |
⊢ (𝜑 → (𝜓 → (𝜒 → 𝜓))) | ||
Theorem | bj-jarrii 33057 | Inference associated with jarri 107. (Contributed by BJ, 29-Mar-2020.) |
⊢ ((𝜑 → 𝜓) → 𝜒) & ⊢ 𝜓 ⇒ ⊢ 𝜒 | ||
Theorem | bj-imim21 33058 | The propositional function (𝜒 → (. → 𝜃)) is decreasing. (Contributed by BJ, 19-Jul-2019.) |
⊢ ((𝜑 → 𝜓) → ((𝜒 → (𝜓 → 𝜃)) → (𝜒 → (𝜑 → 𝜃)))) | ||
Theorem | bj-imim21i 33059 | Inference associated with bj-imim21 33058. Its associated inference is syl5 34. (Contributed by BJ, 19-Jul-2019.) |
⊢ (𝜑 → 𝜓) ⇒ ⊢ ((𝜒 → (𝜓 → 𝜃)) → (𝜒 → (𝜑 → 𝜃))) | ||
Theorem | bj-syl66ib 33060 | A mixed syllogism inference derived from syl6ib 243. In addition to bj-dvelimdv1 33351, it can also shorten alexsubALTlem4 22224 (4821>4812), supsrlem 10248 (2868>2863). (Contributed by BJ, 20-Oct-2021.) |
⊢ (𝜑 → (𝜓 → 𝜃)) & ⊢ (𝜃 → 𝜏) & ⊢ (𝜏 ↔ 𝜒) ⇒ ⊢ (𝜑 → (𝜓 → 𝜒)) | ||
Theorem | bj-orim2 33061 | Proof of orim2 995 from the axiomatic definition of disjunction (olc 899, orc 898, jao 988) and minimal implicational calculus. (Contributed by BJ, 4-Apr-2021.) (Proof modification is discouraged.) |
⊢ ((𝜑 → 𝜓) → ((𝜒 ∨ 𝜑) → (𝜒 ∨ 𝜓))) | ||
Theorem | bj-peirce 33062 | Proof of peirce 194 from minimal implicational calculus, the axiomatic definition of disjunction (olc 899, orc 898, jao 988), and Curry's axiom curryax 922. (Contributed by BJ, 4-Apr-2021.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (((𝜑 → 𝜓) → 𝜑) → 𝜑) | ||
Theorem | bj-currypeirce 33063 | Curry's axiom (a non-intuitionistic statement sometimes called a paradox of material implication) implies Peirce's axiom peirce 194 over minimal implicational calculus and the axiomatic definition of disjunction (olc 899, orc 898, jao 988). A shorter proof from bj-orim2 33061, pm1.2 932, syl6com 37 is possible if we accept to use pm1.2 932, itself a direct consequence of jao 988. (Contributed by BJ, 15-Jun-2021.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ ((𝜑 ∨ (𝜑 → 𝜓)) → (((𝜑 → 𝜓) → 𝜑) → 𝜑)) | ||
Theorem | bj-peircecurry 33064 | Peirce's axiom peirce 194 implies Curry's axiom over minimal implicational calculus and the axiomatic definition of disjunction (olc 899, orc 898, jao 988). See comment of bj-currypeirce 33063. (Contributed by BJ, 15-Jun-2021.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (𝜑 ∨ (𝜑 → 𝜓)) | ||
Theorem | bj-con2com 33065 | A commuted form of the contrapositive, true in minimal calculus. (Contributed by BJ, 19-Mar-2020.) |
⊢ (𝜑 → ((𝜓 → ¬ 𝜑) → ¬ 𝜓)) | ||
Theorem | bj-con2comi 33066 | Inference associated with bj-con2com 33065. Its associated inference is mt2 192. TODO: when in the main part, add to mt2 192 that it is the inference associated with bj-con2comi 33066. (Contributed by BJ, 19-Mar-2020.) |
⊢ 𝜑 ⇒ ⊢ ((𝜓 → ¬ 𝜑) → ¬ 𝜓) | ||
Theorem | bj-pm2.01i 33067 | Inference associated with the weak Clavius law pm2.01 181. (Contributed by BJ, 30-Mar-2020.) |
⊢ (𝜑 → ¬ 𝜑) ⇒ ⊢ ¬ 𝜑 | ||
Theorem | bj-nimn 33068 | If a formula is true, then it does not imply its negation. (Contributed by BJ, 19-Mar-2020.) A shorter proof is possible using id 22 and jc 161, however, the present proof uses theorems that are more basic than jc 161. (Proof modification is discouraged.) |
⊢ (𝜑 → ¬ (𝜑 → ¬ 𝜑)) | ||
Theorem | bj-nimni 33069 | Inference associated with bj-nimn 33068. (Contributed by BJ, 19-Mar-2020.) |
⊢ 𝜑 ⇒ ⊢ ¬ (𝜑 → ¬ 𝜑) | ||
Theorem | bj-peircei 33070 | Inference associated with peirce 194. (Contributed by BJ, 30-Mar-2020.) |
⊢ ((𝜑 → 𝜓) → 𝜑) ⇒ ⊢ 𝜑 | ||
Theorem | bj-looinvi 33071 | Inference associated with looinv 195. Its associated inference is bj-looinvii 33072. (Contributed by BJ, 30-Mar-2020.) |
⊢ ((𝜑 → 𝜓) → 𝜓) ⇒ ⊢ ((𝜓 → 𝜑) → 𝜑) | ||
Theorem | bj-looinvii 33072 | Inference associated with bj-looinvi 33071. (Contributed by BJ, 30-Mar-2020.) |
⊢ ((𝜑 → 𝜓) → 𝜓) & ⊢ (𝜓 → 𝜑) ⇒ ⊢ 𝜑 | ||
A few lemmas about disjunction. The fundamental theorems in this family are the dual statements pm4.71 553 and pm4.72 977. See also biort 964 and biorf 965. | ||
Theorem | bj-jaoi1 33073 | Shortens orfa2 34422 (58>53), pm1.2 932 (20>18), pm1.2 932 (20>18), pm2.4 935 (31>25), pm2.41 936 (31>25), pm2.42 971 (38>32), pm3.2ni 909 (43>39), pm4.44 1024 (55>51). (Contributed by BJ, 30-Sep-2019.) |
⊢ (𝜑 → 𝜓) ⇒ ⊢ ((𝜑 ∨ 𝜓) → 𝜓) | ||
Theorem | bj-jaoi2 33074 | Shortens consensus 1079 (110>106), elnn0z 11717 (336>329), pm1.2 932 (20>19), pm3.2ni 909 (43>39), pm4.44 1024 (55>51). (Contributed by BJ, 30-Sep-2019.) |
⊢ (𝜑 → 𝜓) ⇒ ⊢ ((𝜓 ∨ 𝜑) → 𝜓) | ||
A few other characterizations of the bicondional. The inter-definability of logical connectives offers many ways to express a given statement. Some useful theorems in this regard are df-or 879, df-an 387, pm4.64 880, imor 884, pm4.62 887 through pm4.67 389, and, for the De Morgan laws, ianor 1009 through pm4.57 1018. | ||
Theorem | bj-dfbi4 33075 | Alternate definition of the biconditional. (Contributed by BJ, 4-Oct-2019.) |
⊢ ((𝜑 ↔ 𝜓) ↔ ((𝜑 ∧ 𝜓) ∨ ¬ (𝜑 ∨ 𝜓))) | ||
Theorem | bj-dfbi5 33076 | Alternate definition of the biconditional. (Contributed by BJ, 4-Oct-2019.) |
⊢ ((𝜑 ↔ 𝜓) ↔ ((𝜑 ∨ 𝜓) → (𝜑 ∧ 𝜓))) | ||
Theorem | bj-dfbi6 33077 | Alternate definition of the biconditional. (Contributed by BJ, 4-Oct-2019.) |
⊢ ((𝜑 ↔ 𝜓) ↔ ((𝜑 ∨ 𝜓) ↔ (𝜑 ∧ 𝜓))) | ||
Theorem | bj-bijust0ALT 33078 | Alternate proof of bijust0 196; shorter but using additional intermediate results. (Contributed by NM, 11-May-1999.) (Proof shortened by Josh Purinton, 29-Dec-2000.) (Revised by BJ, 19-Mar-2020.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ ¬ ((𝜑 → 𝜑) → ¬ (𝜑 → 𝜑)) | ||
Theorem | bj-bijust00 33079 | A self-implication does not imply the negation of a self-implication. Most general theorem of which bijust 197 is an instance (bijust0 196 and bj-bijust0ALT 33078 are therefore also instances of it). (Contributed by BJ, 7-Sep-2022.) |
⊢ ¬ ((𝜑 → 𝜑) → ¬ (𝜓 → 𝜓)) | ||
Theorem | bj-consensus 33080 | Version of consensus 1079 expressed using the conditional operator. (Remark: it may be better to express it as consensus 1079, using only binary connectives, and hinting at the fact that it is a Boolean algebra identity, like the absorption identities.) (Contributed by BJ, 30-Sep-2019.) |
⊢ ((if-(𝜑, 𝜓, 𝜒) ∨ (𝜓 ∧ 𝜒)) ↔ if-(𝜑, 𝜓, 𝜒)) | ||
Theorem | bj-consensusALT 33081 | Alternate proof of bj-consensus 33080. (Contributed by BJ, 30-Sep-2019.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ ((if-(𝜑, 𝜓, 𝜒) ∨ (𝜓 ∧ 𝜒)) ↔ if-(𝜑, 𝜓, 𝜒)) | ||
Theorem | bj-dfifc2 33082* | This should be the alternate definition of "ifc" if "if-" enters the main part. (Contributed by BJ, 20-Sep-2019.) |
⊢ if(𝜑, 𝐴, 𝐵) = {𝑥 ∣ ((𝜑 ∧ 𝑥 ∈ 𝐴) ∨ (¬ 𝜑 ∧ 𝑥 ∈ 𝐵))} | ||
Theorem | bj-df-ifc 33083* | The definition of "ifc" if "if-" enters the main part. This is in line with the definition of a class as the extension of a predicate in df-clab 2812. (Contributed by BJ, 20-Sep-2019.) |
⊢ if(𝜑, 𝐴, 𝐵) = {𝑥 ∣ if-(𝜑, 𝑥 ∈ 𝐴, 𝑥 ∈ 𝐵)} | ||
Theorem | bj-ififc 33084* | A theorem linking if- and if. (Contributed by BJ, 24-Sep-2019.) |
⊢ (𝑥 ∈ if(𝜑, 𝐴, 𝐵) ↔ if-(𝜑, 𝑥 ∈ 𝐴, 𝑥 ∈ 𝐵)) | ||
Miscellaneous theorems of propositional calculus. | ||
Theorem | bj-imbi12 33085 | Uncurried (imported) form of imbi12 338. (Contributed by BJ, 6-May-2019.) |
⊢ (((𝜑 ↔ 𝜓) ∧ (𝜒 ↔ 𝜃)) → ((𝜑 → 𝜒) ↔ (𝜓 → 𝜃))) | ||
Theorem | bj-biorfi 33086 | This should be labeled "biorfi" while the current biorfi 967 should be labeled "biorfri". The dual of biorf 965 is not biantr 840 but iba 523 (and ibar 524). So there should also be a "biorfr". (Note that these four statements can actually be strengthened to biconditionals.) (Contributed by BJ, 26-Oct-2019.) (Proof modification is discouraged.) |
⊢ ¬ 𝜑 ⇒ ⊢ (𝜓 ↔ (𝜑 ∨ 𝜓)) | ||
Theorem | bj-falor 33087 | Dual of truan 1668 (which has biconditional reversed). (Contributed by BJ, 26-Oct-2019.) (Proof modification is discouraged.) |
⊢ (𝜑 ↔ (⊥ ∨ 𝜑)) | ||
Theorem | bj-falor2 33088 | Dual of truan 1668. (Contributed by BJ, 26-Oct-2019.) (Proof modification is discouraged.) |
⊢ ((⊥ ∨ 𝜑) ↔ 𝜑) | ||
Theorem | bj-bibibi 33089 | A property of the biconditional. (Contributed by BJ, 26-Oct-2019.) (Proof modification is discouraged.) |
⊢ (𝜑 ↔ (𝜓 ↔ (𝜑 ↔ 𝜓))) | ||
Theorem | bj-imn3ani 33090 | Duplication of bnj1224 31407. Three-fold version of imnani 391. (Contributed by Jonathan Ben-Naim, 3-Jun-2011.) (Revised by BJ, 22-Oct-2019.) (Proof modification is discouraged.) |
⊢ ¬ (𝜑 ∧ 𝜓 ∧ 𝜒) ⇒ ⊢ ((𝜑 ∧ 𝜓) → ¬ 𝜒) | ||
Theorem | bj-andnotim 33091 | Two ways of expressing a certain ternary connective. Note the respective positions of the three formulas on each side of the biconditional. (Contributed by BJ, 6-Oct-2018.) |
⊢ (((𝜑 ∧ ¬ 𝜓) → 𝜒) ↔ ((𝜑 → 𝜓) ∨ 𝜒)) | ||
Theorem | bj-bi3ant 33092 | This used to be in the main part. (Contributed by Wolf Lammen, 14-May-2013.) (Revised by BJ, 14-Jun-2019.) |
⊢ (𝜑 → (𝜓 → 𝜒)) ⇒ ⊢ (((𝜃 → 𝜏) → 𝜑) → (((𝜏 → 𝜃) → 𝜓) → ((𝜃 ↔ 𝜏) → 𝜒))) | ||
Theorem | bj-bisym 33093 | This used to be in the main part. (Contributed by Wolf Lammen, 14-May-2013.) (Revised by BJ, 14-Jun-2019.) |
⊢ (((𝜑 → 𝜓) → (𝜒 → 𝜃)) → (((𝜓 → 𝜑) → (𝜃 → 𝜒)) → ((𝜑 ↔ 𝜓) → (𝜒 ↔ 𝜃)))) | ||
In this section, we prove some theorems related to modal logic. For modal logic, we refer to https://en.wikipedia.org/wiki/Kripke_semantics, https://en.wikipedia.org/wiki/Modal_logic and https://plato.stanford.edu/entries/logic-modal/. Monadic first-order logic (i.e., with quantification over only one variable) is bi-interpretable with modal logic, by mapping ∀𝑥 to "necessity" (generally denoted by a box) and ∃𝑥 to "possibility" (generally denoted by a diamond). Therefore, we use these quantifiers so as not to introduce new symbols. (To be strictly within modal logic, we should add disjoint variable conditions between 𝑥 and any other metavariables appearing in the statements.) For instance, ax-gen 1894 corresponds to the necessitation rule of modal logic, and ax-4 1908 corresponds to the distributivity axiom (K) of modal logic, also called the Kripke scheme. Modal logics satisfying these rule and axiom are called "normal modal logics", of which the most important modal logics are. The minimal normal modal logic is also denoted by (K). Here are a few normal modal logics with their axiomatizations (on top of (K)): (K) axiomatized by no supplementary axioms; (T) axiomatized by the axiom T; (K4) axiomatized by the axiom 4; (S4) axiomatized by the axioms T,4; (S5) axiomatized by the axioms T,5 or D,B,4; (GL) axiomatized by the axiom GL. The last one, called Gödel–Löb logic or provability logic, is important because it describes exactly the properties of provability in Peano arithmetic, as proved by Robert Solovay. See for instance https://plato.stanford.edu/entries/logic-provability/. A basic result in this logic is bj-gl4 33098. | ||
Theorem | bj-axdd2 33094 | This implication, proved using only ax-gen 1894 and ax-4 1908 on top of propositional calculus (hence holding, up to the standard interpretation, in any normal modal logic), shows that the axiom scheme ⊢ ∃𝑥⊤ implies the axiom scheme ⊢ (∀𝑥𝜑 → ∃𝑥𝜑). These correspond to the modal axiom (D), and in predicate calculus, they assert that the universe of discourse is nonempty. For the converse, see bj-axd2d 33095. (Contributed by BJ, 16-May-2019.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (∃𝑥𝜑 → (∀𝑥𝜓 → ∃𝑥𝜓)) | ||
Theorem | bj-axd2d 33095 | This implication, proved using only ax-gen 1894 on top of propositional calculus (hence holding, up to the standard interpretation, in any modal logic), shows that the axiom scheme ⊢ (∀𝑥𝜑 → ∃𝑥𝜑) implies the axiom scheme ⊢ ∃𝑥⊤. These correspond to the modal axiom (D), and in predicate calculus, they assert that the universe of discourse is nonempty. For the converse, see bj-axdd2 33094. (Contributed by BJ, 16-May-2019.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ ((∀𝑥⊤ → ∃𝑥⊤) → ∃𝑥⊤) | ||
Theorem | bj-axtd 33096 | This implication, proved from propositional calculus only (hence holding, up to the standard interpretation, in any modal logic), shows that the axiom scheme ⊢ (∀𝑥𝜑 → 𝜑) (modal T) implies the axiom scheme ⊢ (∀𝑥𝜑 → ∃𝑥𝜑) (modal D). See also bj-axdd2 33094 and bj-axd2d 33095. (Contributed by BJ, 16-May-2019.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ ((∀𝑥 ¬ 𝜑 → ¬ 𝜑) → ((∀𝑥𝜑 → 𝜑) → (∀𝑥𝜑 → ∃𝑥𝜑))) | ||
Theorem | bj-gl4lem 33097 | Lemma for bj-gl4 33098. Note that this proof holds in the modal logic (K). (Contributed by BJ, 12-Dec-2019.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (∀𝑥𝜑 → ∀𝑥(∀𝑥(∀𝑥𝜑 ∧ 𝜑) → (∀𝑥𝜑 ∧ 𝜑))) | ||
Theorem | bj-gl4 33098 | In a normal modal logic, the modal axiom GL implies the modal axiom (4). Note that the antecedent of bj-gl4 33098 is an instance of the axiom GL, with 𝜑 replaced by (∀𝑥𝜑 ∧ 𝜑), sometimes called the "strong necessity" of 𝜑. (Contributed by BJ, 12-Dec-2019.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ ((∀𝑥(∀𝑥(∀𝑥𝜑 ∧ 𝜑) → (∀𝑥𝜑 ∧ 𝜑)) → ∀𝑥(∀𝑥𝜑 ∧ 𝜑)) → (∀𝑥𝜑 → ∀𝑥∀𝑥𝜑)) | ||
Theorem | bj-axc4 33099 | Over minimal calculus, the modal axiom (4) (hba1 2325) and the modal axiom (K) (ax-4 1908) together imply axc4 2352. (Contributed by BJ, 29-Nov-2020.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ ((∀𝑥𝜑 → ∀𝑥∀𝑥𝜑) → ((∀𝑥(∀𝑥𝜑 → 𝜓) → (∀𝑥∀𝑥𝜑 → ∀𝑥𝜓)) → (∀𝑥(∀𝑥𝜑 → 𝜓) → (∀𝑥𝜑 → ∀𝑥𝜓)))) | ||
In this section, we assume that, on top of propositional calculus, there is given a provability predicate Prv satisfying the three axioms ax-prv1 33101 and ax-prv2 33102 and ax-prv3 33103. Note the similarity with ax-gen 1894, ax-4 1908 and hba1 2325 respectively. These three properties of Prv are often called the Hilbert–Bernays–Löb derivability conditions, or the Hilbert–Bernays provability conditions. This corresponds to the modal logic (K4) (see previous section for modal logic). The interpretation of provability logic is the following: we are given a background first-order theory T, the wff Prv 𝜑 means "𝜑 is provable in T", and the turnstile ⊢ indicates provability in T. Beware that "provability logic" often means (K) augmented with the Gödel–Löb axiom GL, which we do not assume here (at least for the moment). See for instance https://plato.stanford.edu/entries/logic-provability/. Provability logic is worth studying because whenever T is a first-order theory containing Robinson arithmetic (a fragment of Peano arithmetic), one can prove (using Gödel numbering, and in the much weaker primitive recursive arithmetic) that there exists in T a provability predicate Prv satisfying the above three axioms. (We do not construct this predicate in this section; this is still a project.) The main theorems of this section are the "easy parts" of the proofs of Gödel's second incompleteness theorem (bj-babygodel 33106) and Löb's theorem (bj-babylob 33107). See the comments of these theorems for details. | ||
Syntax | cprvb 33100 | Syntax for the provability predicate. |
wff Prv 𝜑 |
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