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Theorem List for Metamath Proof Explorer - 34301-34400   *Has distinct variable group(s)
TypeLabelDescription
Statement
 
Theoremdnibnd 34301* 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)))    &   (𝜑𝐴 ∈ ℝ)    &   (𝜑𝐵 ∈ ℝ)       (𝜑 → (abs‘((𝑇𝐵) − (𝑇𝐴))) ≤ (abs‘(𝐵𝐴)))
 
Theoremdnicn 34302 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)
 
Theoremknoppcnlem1 34303* Lemma for knoppcn 34314. (Contributed by Asger C. Ipsen, 4-Apr-2021.)
𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   (𝜑𝐴 ∈ ℝ)    &   (𝜑𝑀 ∈ ℕ0)       (𝜑 → ((𝐹𝐴)‘𝑀) = ((𝐶𝑀) · (𝑇‘(((2 · 𝑁)↑𝑀) · 𝐴))))
 
Theoremknoppcnlem2 34304* Lemma for knoppcn 34314. (Contributed by Asger C. Ipsen, 4-Apr-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.)
𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥)))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)    &   (𝜑𝐴 ∈ ℝ)    &   (𝜑𝑀 ∈ ℕ0)       (𝜑 → ((𝐶𝑀) · (𝑇‘(((2 · 𝑁)↑𝑀) · 𝐴))) ∈ ℝ)
 
Theoremknoppcnlem3 34305* Lemma for knoppcn 34314. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)    &   (𝜑𝐴 ∈ ℝ)    &   (𝜑𝑀 ∈ ℕ0)       (𝜑 → ((𝐹𝐴)‘𝑀) ∈ ℝ)
 
Theoremknoppcnlem4 34306* Lemma for knoppcn 34314. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)    &   (𝜑𝐴 ∈ ℝ)    &   (𝜑𝑀 ∈ ℕ0)       (𝜑 → (abs‘((𝐹𝐴)‘𝑀)) ≤ ((𝑚 ∈ ℕ0 ↦ ((abs‘𝐶)↑𝑚))‘𝑀))
 
Theoremknoppcnlem5 34307* Lemma for knoppcn 34314. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)       (𝜑 → (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹𝑧)‘𝑚))):ℕ0⟶(ℂ ↑m ℝ))
 
Theoremknoppcnlem6 34308* Lemma for knoppcn 34314. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)    &   (𝜑 → (abs‘𝐶) < 1)       (𝜑 → seq0( ∘f + , (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹𝑧)‘𝑚)))) ∈ dom (⇝𝑢‘ℝ))
 
Theoremknoppcnlem7 34309* Lemma for knoppcn 34314. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)    &   (𝜑𝑀 ∈ ℕ0)       (𝜑 → (seq0( ∘f + , (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹𝑧)‘𝑚))))‘𝑀) = (𝑤 ∈ ℝ ↦ (seq0( + , (𝐹𝑤))‘𝑀)))
 
Theoremknoppcnlem8 34310* Lemma for knoppcn 34314. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)       (𝜑 → seq0( ∘f + , (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹𝑧)‘𝑚)))):ℕ0⟶(ℂ ↑m ℝ))
 
Theoremknoppcnlem9 34311* Lemma for knoppcn 34314. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)    &   (𝜑 → (abs‘𝐶) < 1)       (𝜑 → seq0( ∘f + , (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹𝑧)‘𝑚))))(⇝𝑢‘ℝ)𝑊)
 
Theoremknoppcnlem10 34312* Lemma for knoppcn 34314. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)    &   (𝜑𝑀 ∈ ℕ0)       (𝜑 → (𝑧 ∈ ℝ ↦ ((𝐹𝑧)‘𝑀)) ∈ ((topGen‘ran (,)) Cn (TopOpen‘ℂfld)))
 
Theoremknoppcnlem11 34313* Lemma for knoppcn 34314. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)       (𝜑 → seq0( ∘f + , (𝑚 ∈ ℕ0 ↦ (𝑧 ∈ ℝ ↦ ((𝐹𝑧)‘𝑚)))):ℕ0⟶(ℝ–cn→ℂ))
 
Theoremknoppcn 34314* 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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)    &   (𝜑 → (abs‘𝐶) < 1)       (𝜑𝑊 ∈ (ℝ–cn→ℂ))
 
Theoremknoppcld 34315* 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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   (𝜑𝐴 ∈ ℝ)    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ ℝ)    &   (𝜑 → (abs‘𝐶) < 1)       (𝜑 → (𝑊𝐴) ∈ ℂ)
 
Theoremunblimceq0lem 34316* Lemma for unblimceq0 34317. (Contributed by Asger C. Ipsen, 12-May-2021.)
(𝜑𝑆 ⊆ ℂ)    &   (𝜑𝐹:𝑆⟶ℂ)    &   (𝜑𝐴 ∈ ℂ)    &   (𝜑 → ∀𝑏 ∈ ℝ+𝑑 ∈ ℝ+𝑥𝑆 ((abs‘(𝑥𝐴)) < 𝑑𝑏 ≤ (abs‘(𝐹𝑥))))       (𝜑 → ∀𝑐 ∈ ℝ+𝑑 ∈ ℝ+𝑦𝑆 (𝑦𝐴 ∧ (abs‘(𝑦𝐴)) < 𝑑𝑐 ≤ (abs‘(𝐹𝑦))))
 
Theoremunblimceq0 34317* If 𝐹 is unbounded near 𝐴 it has no limit at 𝐴. (Contributed by Asger C. Ipsen, 12-May-2021.)
(𝜑𝑆 ⊆ ℂ)    &   (𝜑𝐹:𝑆⟶ℂ)    &   (𝜑𝐴 ∈ ℂ)    &   (𝜑 → ∀𝑏 ∈ ℝ+𝑑 ∈ ℝ+𝑥𝑆 ((abs‘(𝑥𝐴)) < 𝑑𝑏 ≤ (abs‘(𝐹𝑥))))       (𝜑 → (𝐹 lim 𝐴) = ∅)
 
Theoremunbdqndv1 34318* If the difference quotient (((𝐹𝑧) − (𝐹𝐴)) / (𝑧𝐴)) is unbounded near 𝐴 then 𝐹 is not differentiable at 𝐴. (Contributed by Asger C. Ipsen, 12-May-2021.)
𝐺 = (𝑧 ∈ (𝑋 ∖ {𝐴}) ↦ (((𝐹𝑧) − (𝐹𝐴)) / (𝑧𝐴)))    &   (𝜑𝑆 ⊆ ℂ)    &   (𝜑𝑋𝑆)    &   (𝜑𝐹:𝑋⟶ℂ)    &   (𝜑 → ∀𝑏 ∈ ℝ+𝑑 ∈ ℝ+𝑥 ∈ (𝑋 ∖ {𝐴})((abs‘(𝑥𝐴)) < 𝑑𝑏 ≤ (abs‘(𝐺𝑥))))       (𝜑 → ¬ 𝐴 ∈ dom (𝑆 D 𝐹))
 
Theoremunbdqndv2lem1 34319 Lemma for unbdqndv2 34321. (Contributed by Asger C. Ipsen, 12-May-2021.)
(𝜑𝐴 ∈ ℂ)    &   (𝜑𝐵 ∈ ℂ)    &   (𝜑𝐶 ∈ ℂ)    &   (𝜑𝐷 ∈ ℂ)    &   (𝜑𝐸 ∈ ℝ+)    &   (𝜑𝐷 ≠ 0)    &   (𝜑 → (2 · 𝐸) ≤ (abs‘((𝐴𝐵) / 𝐷)))       (𝜑 → ((𝐸 · (abs‘𝐷)) ≤ (abs‘(𝐴𝐶)) ∨ (𝐸 · (abs‘𝐷)) ≤ (abs‘(𝐵𝐶))))
 
Theoremunbdqndv2lem2 34320* Lemma for unbdqndv2 34321. (Contributed by Asger C. Ipsen, 12-May-2021.)
𝐺 = (𝑧 ∈ (𝑋 ∖ {𝐴}) ↦ (((𝐹𝑧) − (𝐹𝐴)) / (𝑧𝐴)))    &   𝑊 = if((𝐵 · (𝑉𝑈)) ≤ (abs‘((𝐹𝑈) − (𝐹𝐴))), 𝑈, 𝑉)    &   (𝜑𝑋 ⊆ ℝ)    &   (𝜑𝐹:𝑋⟶ℂ)    &   (𝜑𝐴𝑋)    &   (𝜑𝐵 ∈ ℝ+)    &   (𝜑𝐷 ∈ ℝ+)    &   (𝜑𝑈𝑋)    &   (𝜑𝑉𝑋)    &   (𝜑𝑈𝑉)    &   (𝜑𝑈𝐴)    &   (𝜑𝐴𝑉)    &   (𝜑 → (𝑉𝑈) < 𝐷)    &   (𝜑 → (2 · 𝐵) ≤ ((abs‘((𝐹𝑉) − (𝐹𝑈))) / (𝑉𝑈)))       (𝜑 → (𝑊 ∈ (𝑋 ∖ {𝐴}) ∧ ((abs‘(𝑊𝐴)) < 𝐷𝐵 ≤ (abs‘(𝐺𝑊)))))
 
Theoremunbdqndv2 34321* Variant of unbdqndv1 34318 with the hypothesis that (((𝐹𝑦) − (𝐹𝑥)) / (𝑦𝑥)) is unbounded where 𝑥𝐴 and 𝐴𝑦. (Contributed by Asger C. Ipsen, 12-May-2021.)
(𝜑𝑋 ⊆ ℝ)    &   (𝜑𝐹:𝑋⟶ℂ)    &   (𝜑 → ∀𝑏 ∈ ℝ+𝑑 ∈ ℝ+𝑥𝑋𝑦𝑋 ((𝑥𝐴𝐴𝑦) ∧ ((𝑦𝑥) < 𝑑𝑥𝑦) ∧ 𝑏 ≤ ((abs‘((𝐹𝑦) − (𝐹𝑥))) / (𝑦𝑥))))       (𝜑 → ¬ 𝐴 ∈ dom (ℝ D 𝐹))
 
Theoremknoppndvlem1 34322 Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 15-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.)
(𝜑𝑁 ∈ ℕ)    &   (𝜑𝐽 ∈ ℤ)    &   (𝜑𝑀 ∈ ℤ)       (𝜑 → ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀) ∈ ℝ)
 
Theoremknoppndvlem2 34323 Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 15-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.)
(𝜑𝑁 ∈ ℕ)    &   (𝜑𝐼 ∈ ℤ)    &   (𝜑𝐽 ∈ ℤ)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝐽 < 𝐼)       (𝜑 → (((2 · 𝑁)↑𝐼) · ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀)) ∈ ℤ)
 
Theoremknoppndvlem3 34324 Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 15-Jun-2021.)
(𝜑𝐶 ∈ (-1(,)1))       (𝜑 → (𝐶 ∈ ℝ ∧ (abs‘𝐶) < 1))
 
Theoremknoppndvlem4 34325* Lemma for knoppndv 34344. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   (𝜑𝐴 ∈ ℝ)    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝑁 ∈ ℕ)       (𝜑 → seq0( + , (𝐹𝐴)) ⇝ (𝑊𝐴))
 
Theoremknoppndvlem5 34326* Lemma for knoppndv 34344. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   (𝜑𝐴 ∈ ℝ)    &   (𝜑𝐶 ∈ ℝ)    &   (𝜑𝑁 ∈ ℕ)       (𝜑 → Σ𝑖 ∈ (0...𝐽)((𝐹𝐴)‘𝑖) ∈ ℝ)
 
Theoremknoppndvlem6 34327* Lemma for knoppndv 34344. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀)    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℕ)       (𝜑 → (𝑊𝐴) = Σ𝑖 ∈ (0...𝐽)((𝐹𝐴)‘𝑖))
 
Theoremknoppndvlem7 34328* Lemma for knoppndv 34344. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀)    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℕ)       (𝜑 → ((𝐹𝐴)‘𝐽) = ((𝐶𝐽) · (𝑇‘(𝑀 / 2))))
 
Theoremknoppndvlem8 34329* Lemma for knoppndv 34344. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀)    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑 → 2 ∥ 𝑀)       (𝜑 → ((𝐹𝐴)‘𝐽) = 0)
 
Theoremknoppndvlem9 34330* Lemma for knoppndv 34344. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀)    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑 → ¬ 2 ∥ 𝑀)       (𝜑 → ((𝐹𝐴)‘𝐽) = ((𝐶𝐽) / 2))
 
Theoremknoppndvlem10 34331* Lemma for knoppndv 34344. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀)    &   𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑀 + 1))    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℕ)       (𝜑 → (abs‘(((𝐹𝐵)‘𝐽) − ((𝐹𝐴)‘𝐽))) = (((abs‘𝐶)↑𝐽) / 2))
 
Theoremknoppndvlem11 34332* Lemma for knoppndv 34344. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   (𝜑𝐴 ∈ ℝ)    &   (𝜑𝐵 ∈ ℝ)    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝑁 ∈ ℕ)       (𝜑 → (abs‘(Σ𝑖 ∈ (0...(𝐽 − 1))((𝐹𝐵)‘𝑖) − Σ𝑖 ∈ (0...(𝐽 − 1))((𝐹𝐴)‘𝑖))) ≤ ((abs‘(𝐵𝐴)) · Σ𝑖 ∈ (0...(𝐽 − 1))(((2 · 𝑁) · (abs‘𝐶))↑𝑖)))
 
Theoremknoppndvlem12 34333 Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 29-Jun-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.)
(𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑 → 1 < (𝑁 · (abs‘𝐶)))       (𝜑 → (((2 · 𝑁) · (abs‘𝐶)) ≠ 1 ∧ 1 < (((2 · 𝑁) · (abs‘𝐶)) − 1)))
 
Theoremknoppndvlem13 34334 Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 1-Jul-2021.) (Revised by Asger C. Ipsen, 5-Jul-2021.)
(𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑 → 1 < (𝑁 · (abs‘𝐶)))       (𝜑𝐶 ≠ 0)
 
Theoremknoppndvlem14 34335* Lemma for knoppndv 34344. (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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀)    &   𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑀 + 1))    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑 → 1 < (𝑁 · (abs‘𝐶)))       (𝜑 → (abs‘(Σ𝑖 ∈ (0...(𝐽 − 1))((𝐹𝐵)‘𝑖) − Σ𝑖 ∈ (0...(𝐽 − 1))((𝐹𝐴)‘𝑖))) ≤ ((((abs‘𝐶)↑𝐽) / 2) · (1 / (((2 · 𝑁) · (abs‘𝐶)) − 1))))
 
Theoremknoppndvlem15 34336* Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 6-Jul-2021.)
𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥)))    &   𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀)    &   𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑀 + 1))    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑 → 1 < (𝑁 · (abs‘𝐶)))       (𝜑 → ((((abs‘𝐶)↑𝐽) / 2) · (1 − (1 / (((2 · 𝑁) · (abs‘𝐶)) − 1)))) ≤ (abs‘((𝑊𝐵) − (𝑊𝐴))))
 
Theoremknoppndvlem16 34337 Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 19-Jul-2021.)
𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀)    &   𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑀 + 1))    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℕ)       (𝜑 → (𝐵𝐴) = (((2 · 𝑁)↑-𝐽) / 2))
 
Theoremknoppndvlem17 34338* Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 12-Aug-2021.)
𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥)))    &   𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑀)    &   𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑀 + 1))    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑 → 1 < (𝑁 · (abs‘𝐶)))       (𝜑 → ((((2 · 𝑁) · (abs‘𝐶))↑𝐽) · (1 − (1 / (((2 · 𝑁) · (abs‘𝐶)) − 1)))) ≤ ((abs‘((𝑊𝐵) − (𝑊𝐴))) / (𝐵𝐴)))
 
Theoremknoppndvlem18 34339* Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 14-Aug-2021.)
(𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐷 ∈ ℝ+)    &   (𝜑𝐸 ∈ ℝ+)    &   (𝜑𝐺 ∈ ℝ+)    &   (𝜑 → 1 < (𝑁 · (abs‘𝐶)))       (𝜑 → ∃𝑗 ∈ ℕ0 ((((2 · 𝑁)↑-𝑗) / 2) < 𝐷𝐸 ≤ ((((2 · 𝑁) · (abs‘𝐶))↑𝑗) · 𝐺)))
 
Theoremknoppndvlem19 34340* Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 17-Aug-2021.)
𝐴 = ((((2 · 𝑁)↑-𝐽) / 2) · 𝑚)    &   𝐵 = ((((2 · 𝑁)↑-𝐽) / 2) · (𝑚 + 1))    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝐻 ∈ ℝ)    &   (𝜑𝑁 ∈ ℕ)       (𝜑 → ∃𝑚 ∈ ℤ (𝐴𝐻𝐻𝐵))
 
Theoremknoppndvlem20 34341 Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 18-Aug-2021.)
(𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑 → 1 < (𝑁 · (abs‘𝐶)))       (𝜑 → (1 − (1 / (((2 · 𝑁) · (abs‘𝐶)) − 1))) ∈ ℝ+)
 
Theoremknoppndvlem21 34342* Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 18-Aug-2021.)
𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥)))    &   𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   𝐺 = (1 − (1 / (((2 · 𝑁) · (abs‘𝐶)) − 1)))    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝐷 ∈ ℝ+)    &   (𝜑𝐸 ∈ ℝ+)    &   (𝜑𝐻 ∈ ℝ)    &   (𝜑𝐽 ∈ ℕ0)    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑 → 1 < (𝑁 · (abs‘𝐶)))    &   (𝜑 → (((2 · 𝑁)↑-𝐽) / 2) < 𝐷)    &   (𝜑𝐸 ≤ ((((2 · 𝑁) · (abs‘𝐶))↑𝐽) · 𝐺))       (𝜑 → ∃𝑎 ∈ ℝ ∃𝑏 ∈ ℝ ((𝑎𝐻𝐻𝑏) ∧ ((𝑏𝑎) < 𝐷𝑎𝑏) ∧ 𝐸 ≤ ((abs‘((𝑊𝑏) − (𝑊𝑎))) / (𝑏𝑎))))
 
Theoremknoppndvlem22 34343* Lemma for knoppndv 34344. (Contributed by Asger C. Ipsen, 19-Aug-2021.)
𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥)))    &   𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝐷 ∈ ℝ+)    &   (𝜑𝐸 ∈ ℝ+)    &   (𝜑𝐻 ∈ ℝ)    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑 → 1 < (𝑁 · (abs‘𝐶)))       (𝜑 → ∃𝑎 ∈ ℝ ∃𝑏 ∈ ℝ ((𝑎𝐻𝐻𝑏) ∧ ((𝑏𝑎) < 𝐷𝑎𝑏) ∧ 𝐸 ≤ ((abs‘((𝑊𝑏) − (𝑊𝑎))) / (𝑏𝑎))))
 
Theoremknoppndv 34344* 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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑 → 1 < (𝑁 · (abs‘𝐶)))       (𝜑 → dom (ℝ D 𝑊) = ∅)
 
Theoremknoppf 34345* 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 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   (𝜑𝐶 ∈ (-1(,)1))    &   (𝜑𝑁 ∈ ℕ)       (𝜑𝑊:ℝ⟶ℝ)
 
Theoremknoppcn2 34346* Variant of knoppcn 34314 with different codomain. (Contributed by Asger C. Ipsen, 25-Aug-2021.)
𝑇 = (𝑥 ∈ ℝ ↦ (abs‘((⌊‘(𝑥 + (1 / 2))) − 𝑥)))    &   𝐹 = (𝑦 ∈ ℝ ↦ (𝑛 ∈ ℕ0 ↦ ((𝐶𝑛) · (𝑇‘(((2 · 𝑁)↑𝑛) · 𝑦)))))    &   𝑊 = (𝑤 ∈ ℝ ↦ Σ𝑖 ∈ ℕ0 ((𝐹𝑤)‘𝑖))    &   (𝜑𝑁 ∈ ℕ)    &   (𝜑𝐶 ∈ (-1(,)1))       (𝜑𝑊 ∈ (ℝ–cn→ℝ))
 
Theoremcnndvlem1 34347* Lemma for cnndv 34349. (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 ((𝐹𝑤)‘𝑖))       (𝑊 ∈ (ℝ–cn→ℝ) ∧ dom (ℝ D 𝑊) = ∅)
 
Theoremcnndvlem2 34348* Lemma for cnndv 34349. (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 ((𝐹𝑤)‘𝑖))       𝑓(𝑓 ∈ (ℝ–cn→ℝ) ∧ dom (ℝ D 𝑓) = ∅)
 
Theoremcnndv 34349 There exists a continuous nowhere differentiable function. The result follows directly from knoppcn 34314 and knoppndv 34344. (Contributed by Asger C. Ipsen, 26-Aug-2021.)
𝑓(𝑓 ∈ (ℝ–cn→ℝ) ∧ dom (ℝ D 𝑓) = ∅)
 
20.15  Mathbox for BJ

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.

 
20.15.1  Propositional calculus

Miscellaneous utility theorems of propositional calculus.

 
20.15.1.1  Derived rules of inference

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.

 
Theorembj-mp2c 34350 A double modus ponens inference. Inference associated with mpd 15. (Contributed by BJ, 24-Sep-2019.)
𝜑    &   (𝜑𝜓)    &   (𝜑 → (𝜓𝜒))       𝜒
 
Theorembj-mp2d 34351 A double modus ponens inference. Inference associated with mpcom 38. (Contributed by BJ, 24-Sep-2019.)
𝜑    &   (𝜑𝜓)    &   (𝜓 → (𝜑𝜒))       𝜒
 
20.15.1.2  A syntactic theorem

In this section, we prove a syntactic theorem (bj-0 34352) asserting that some formula is well-formed. Then, we use this syntactic theorem to shorten the proof of a "usual" theorem (bj-1 34353) and explain in the comment of that theorem why this phenomenon is unusual.

 
Theorembj-0 34352 A syntactic theorem. See the section comment and the comment of bj-1 34353. 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 2114 and weq 1969. (Contributed by BJ, 24-Sep-2019.) (Proof modification is discouraged.) (New usage is discouraged.)
wff ((𝜑𝜓) → 𝜒)
 
Theorembj-1 34353 In this proof, the use of the syntactic theorem bj-0 34352 allows to reduce the total length by one (non-essential) step. See also the section comment and the comment of bj-0 34352. Since bj-0 34352 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 34352 as a theorem referencing it). The full proof reads $= wph wps wch bj-0 id $. (while, without using bj-0 34352, 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 1969 or wel 2114). 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 34353 is a special instance of id 22. (Contributed by BJ, 24-Sep-2019.) (Proof modification is discouraged.) (New usage is discouraged.)

(((𝜑𝜓) → 𝜒) → ((𝜑𝜓) → 𝜒))
 
20.15.1.3  Minimal implicational calculus
 
Theorembj-a1k 34354 Weakening of ax-1 6. As a consequence, its associated inference is an instance (where we allow extra hypotheses) of ax-1 6. Its commuted form is 2a1 28 (but bj-a1k 34354 does not require ax-2 7). This shortens the proofs of dfwe2 7509 (937>925), ordunisuc2 7572 (789>777), r111 9270 (558>545), smo11 8023 (1176>1164). (Contributed by BJ, 11-Aug-2020.) (Proof modification is discouraged.)
(𝜑 → (𝜓 → (𝜒𝜓)))
 
Theorembj-poni 34355 Inference associated with "pon", pm2.27 42. Its associated inference is ax-mp 5. (Contributed by BJ, 30-Jul-2024.)
𝜑       ((𝜑𝜓) → 𝜓)
 
Theorembj-nnclav 34356 When is substituted for 𝜓, this formula is the Clavius law with a doubly negated consequent, which is therefore a minimalistic tautology. Notice the non-intuitionistic proof from peirce 205 and pm2.27 42 chained using syl 17. (Contributed by BJ, 4-Dec-2023.)
(((𝜑𝜓) → 𝜑) → ((𝜑𝜓) → 𝜓))
 
Theorembj-nnclavi 34357 Inference associated with bj-nnclav 34356. Its associated inference is an instance of syl 17. Notice the non-intuitionistic proof from bj-peircei 34376 and bj-poni 34355. (Contributed by BJ, 30-Jul-2024.)
((𝜑𝜓) → 𝜑)       ((𝜑𝜓) → 𝜓)
 
Theorembj-nnclavc 34358 Commuted form of bj-nnclav 34356. Notice the non-intuitionistic proof from bj-peircei 34376 and imim1i 63. (Contributed by BJ, 30-Jul-2024.) A proof which is shorter when compressed uses embantd 59. (Proof modification is discouraged.)
((𝜑𝜓) → (((𝜑𝜓) → 𝜑) → 𝜓))
 
Theorembj-nnclavci 34359 Inference associated with bj-nnclavc 34358. Its associated inference is an instance of syl 17. Notice the non-intuitionistic proof from peirce 205 and syl 17. (Contributed by BJ, 30-Jul-2024.)
(𝜑𝜓)       (((𝜑𝜓) → 𝜑) → 𝜓)
 
Theorembj-jarrii 34360 Inference associated with jarri 107. Contrary to it , it does not require ax-2 7, but only ax-mp 5 and ax-1 6. (Contributed by BJ, 29-Mar-2020.) (Proof modification is discouraged.)
((𝜑𝜓) → 𝜒)    &   𝜓       𝜒
 
Theorembj-imim21 34361 The propositional function (𝜒 → (. → 𝜃)) is decreasing. (Contributed by BJ, 19-Jul-2019.)
((𝜑𝜓) → ((𝜒 → (𝜓𝜃)) → (𝜒 → (𝜑𝜃))))
 
Theorembj-imim21i 34362 Inference associated with bj-imim21 34361. Its associated inference is syl5 34. (Contributed by BJ, 19-Jul-2019.)
(𝜑𝜓)       ((𝜒 → (𝜓𝜃)) → (𝜒 → (𝜑𝜃)))
 
Theorembj-peircestab 34363 Over minimal implicational calculus, Peirce's law implies the double negation of the stability of any formula (that is the interpretation when is substituted for 𝜓 and for 𝜒). Therefore, the double negation of the stability of any formula is provable in classical refutability calculus. It is also provable in intuitionistic calculus (see iset.mm/bj-nnst) but it is not provable in minimal calculus (see bj-stabpeirce 34364). (Contributed by BJ, 30-Nov-2023.) Axiom ax-3 8 is only used through Peirce's law peirce 205. (Proof modification is discouraged.)
(((((𝜑𝜓) → 𝜒) → 𝜑) → 𝜒) → 𝜒)
 
Theorembj-stabpeirce 34364 This minimal implicational calculus tautology is used in the following argument: When 𝜑, 𝜓, 𝜒, 𝜃, 𝜏 are replaced respectively by (𝜑 → ⊥), ⊥, 𝜑, ⊥, ⊥, the antecedent becomes ¬ ¬ (¬ ¬ 𝜑𝜑), that is, the double negation of the stability of 𝜑. If that statement were provable in minimal calculus, then, since plays no particular role in minimal calculus, also the statement with 𝜓 in place of would be provable. The corresponding consequent is (((𝜓𝜑) → 𝜓) → 𝜓), that is, the non-intuitionistic Peirce law. Therefore, the double negation of the stability of any formula is not provable in minimal calculus. However, it is provable both in intuitionistic calculus (see iset.mm/bj-nnst) and in classical refutability calculus (see bj-peircestab 34363). (Contributed by BJ, 30-Nov-2023.) (Revised by BJ, 30-Jul-2024.) (Proof modification is discouraged.)
(((((𝜑𝜓) → 𝜒) → 𝜃) → 𝜏) → (((𝜓𝜒) → 𝜃) → 𝜏))
 
20.15.1.4  Positive calculus

Positive calculus is understood to be intuitionistic.

 
Theorembj-syl66ib 34365 A mixed syllogism inference derived from syl6ib 254. In addition to bj-dvelimdv1 34656, it can also shorten alexsubALTlem4 22794 (4821>4812), supsrlem 10604 (2868>2863). (Contributed by BJ, 20-Oct-2021.)
(𝜑 → (𝜓𝜃))    &   (𝜃𝜏)    &   (𝜏𝜒)       (𝜑 → (𝜓𝜒))
 
Theorembj-orim2 34366 Proof of orim2 967 from the axiomatic definition of disjunction (olc 867, orc 866, jao 960) and minimal implicational calculus. (Contributed by BJ, 4-Apr-2021.) (Proof modification is discouraged.)
((𝜑𝜓) → ((𝜒𝜑) → (𝜒𝜓)))
 
Theorembj-currypeirce 34367 Curry's axiom curryax 893 (a non-intuitionistic positive statement sometimes called a paradox of material implication) implies Peirce's axiom peirce 205 over minimal implicational calculus and the axiomatic definition of disjunction (actually, only the elimination axiom jao 960 via its inference form jaoi 856; the introduction axioms olc 867 and orc 866 are not needed). Note that this theorem shows that actually, the standard instance of curryax 893 implies the standard instance of peirce 205, which is not the case for the converse bj-peircecurry 34368. (Contributed by BJ, 15-Jun-2021.) (Proof modification is discouraged.) (New usage is discouraged.)
((𝜑 ∨ (𝜑𝜓)) → (((𝜑𝜓) → 𝜑) → 𝜑))
 
Theorembj-peircecurry 34368 Peirce's axiom peirce 205 implies Curry's axiom curryax 893 over minimal implicational calculus and the axiomatic definition of disjunction (actually, only the introduction axioms olc 867 and orc 866; the elimination axiom jao 960 is not needed). See bj-currypeirce 34367 for the converse. (Contributed by BJ, 15-Jun-2021.) (Proof modification is discouraged.) (New usage is discouraged.)
(𝜑 ∨ (𝜑𝜓))
 
Theorembj-animbi 34369 Conjunction in terms of implication and biconditional. Note that the proof is intuitionistic (use of ax-3 8 comes from the unusual definition of the biconditional in set.mm). (Contributed by BJ, 23-Sep-2023.)
((𝜑𝜓) ↔ (𝜑 ↔ (𝜑𝜓)))
 
Theorembj-currypara 34370 Curry's paradox. Note that the proof is intuitionistic (use ax-3 8 comes from the unusual definition of the biconditional in set.mm). The paradox comes from the case where 𝜑 is the self-referential sentence "If this sentence is true, then 𝜓", so that one can prove everything. Therefore, a consistent system cannot allow the formation of such self-referential sentences. This has lead to the study of logics rejecting contraction pm2.43 56, such as affine logic and linear logic. (Contributed by BJ, 23-Sep-2023.)
((𝜑 ↔ (𝜑𝜓)) → 𝜓)
 
20.15.1.5  Implication and negation
 
Theorembj-con2com 34371 A commuted form of the contrapositive, true in minimal calculus. (Contributed by BJ, 19-Mar-2020.)
(𝜑 → ((𝜓 → ¬ 𝜑) → ¬ 𝜓))
 
Theorembj-con2comi 34372 Inference associated with bj-con2com 34371. Its associated inference is mt2 203. TODO: when in the main part, add to mt2 203 that it is the inference associated with bj-con2comi 34372. (Contributed by BJ, 19-Mar-2020.)
𝜑       ((𝜓 → ¬ 𝜑) → ¬ 𝜓)
 
Theorembj-pm2.01i 34373 Inference associated with the weak Clavius law pm2.01 192. (Contributed by BJ, 30-Mar-2020.)
(𝜑 → ¬ 𝜑)        ¬ 𝜑
 
Theorembj-nimn 34374 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 164, however, the present proof uses theorems that are more basic than jc 164. (Proof modification is discouraged.)
(𝜑 → ¬ (𝜑 → ¬ 𝜑))
 
Theorembj-nimni 34375 Inference associated with bj-nimn 34374. (Contributed by BJ, 19-Mar-2020.)
𝜑        ¬ (𝜑 → ¬ 𝜑)
 
Theorembj-peircei 34376 Inference associated with peirce 205. (Contributed by BJ, 30-Mar-2020.)
((𝜑𝜓) → 𝜑)       𝜑
 
Theorembj-looinvi 34377 Inference associated with looinv 206. Its associated inference is bj-looinvii 34378. (Contributed by BJ, 30-Mar-2020.)
((𝜑𝜓) → 𝜓)       ((𝜓𝜑) → 𝜑)
 
Theorembj-looinvii 34378 Inference associated with bj-looinvi 34377. (Contributed by BJ, 30-Mar-2020.)
((𝜑𝜓) → 𝜓)    &   (𝜓𝜑)       𝜑
 
20.15.1.6  Disjunction

A few lemmas about disjunction. The fundamental theorems in this family are the dual statements pm4.71 561 and pm4.72 949. See also biort 935 and biorf 936.

 
Theorembj-jaoi1 34379 Shortens orfa2 35856 (58>53), pm1.2 903 (20>18), pm1.2 903 (20>18), pm2.4 906 (31>25), pm2.41 907 (31>25), pm2.42 942 (38>32), pm3.2ni 880 (43>39), pm4.44 996 (55>51). (Contributed by BJ, 30-Sep-2019.)
(𝜑𝜓)       ((𝜑𝜓) → 𝜓)
 
Theorembj-jaoi2 34380 Shortens consensus 1052 (110>106), elnn0z 12068 (336>329), pm1.2 903 (20>19), pm3.2ni 880 (43>39), pm4.44 996 (55>51). (Contributed by BJ, 30-Sep-2019.)
(𝜑𝜓)       ((𝜓𝜑) → 𝜓)
 
20.15.1.7  Logical equivalence

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 847, df-an 400, pm4.64 848, imor 852, pm4.62 855 through pm4.67 402, and, for the De Morgan laws, ianor 981 through pm4.57 990.

 
Theorembj-dfbi4 34381 Alternate definition of the biconditional. (Contributed by BJ, 4-Oct-2019.)
((𝜑𝜓) ↔ ((𝜑𝜓) ∨ ¬ (𝜑𝜓)))
 
Theorembj-dfbi5 34382 Alternate definition of the biconditional. (Contributed by BJ, 4-Oct-2019.)
((𝜑𝜓) ↔ ((𝜑𝜓) → (𝜑𝜓)))
 
Theorembj-dfbi6 34383 Alternate definition of the biconditional. (Contributed by BJ, 4-Oct-2019.)
((𝜑𝜓) ↔ ((𝜑𝜓) ↔ (𝜑𝜓)))
 
Theorembj-bijust0ALT 34384 Alternate proof of bijust0 207; 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.)
¬ ((𝜑𝜑) → ¬ (𝜑𝜑))
 
Theorembj-bijust00 34385 A self-implication does not imply the negation of a self-implication. Most general theorem of which bijust 208 is an instance (bijust0 207 and bj-bijust0ALT 34384 are therefore also instances of it). (Contributed by BJ, 7-Sep-2022.)
¬ ((𝜑𝜑) → ¬ (𝜓𝜓))
 
20.15.1.8  The conditional operator for propositions
 
Theorembj-consensus 34386 Version of consensus 1052 expressed using the conditional operator. (Remark: it may be better to express it as consensus 1052, 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) ∨ (𝜓𝜒)) ↔ if-(𝜑, 𝜓, 𝜒))
 
Theorembj-consensusALT 34387 Alternate proof of bj-consensus 34386. (Contributed by BJ, 30-Sep-2019.) (Proof modification is discouraged.) (New usage is discouraged.)
((if-(𝜑, 𝜓, 𝜒) ∨ (𝜓𝜒)) ↔ if-(𝜑, 𝜓, 𝜒))
 
Theorembj-df-ifc 34388* Candidate definition for the conditional operator for classes. This is in line with the definition of a class as the extension of a predicate in df-clab 2717. We reprove the current df-if 4412 from it in bj-dfif 34389. (Contributed by BJ, 20-Sep-2019.) (Proof modification is discouraged.)
if(𝜑, 𝐴, 𝐵) = {𝑥 ∣ if-(𝜑, 𝑥𝐴, 𝑥𝐵)}
 
Theorembj-dfif 34389* Alternate definition of the conditional operator for classes, which used to be the main definition. (Contributed by BJ, 26-Dec-2023.) (Proof modification is discouraged.)
if(𝜑, 𝐴, 𝐵) = {𝑥 ∣ ((𝜑𝑥𝐴) ∨ (¬ 𝜑𝑥𝐵))}
 
Theorembj-ififc 34390 A biconditional connecting the conditional operator for propositions and the conditional operator for classes. Note that there is no sethood hypothesis on 𝑋: it is implied by either side. (Contributed by BJ, 24-Sep-2019.) Generalize statement from setvar 𝑥 to class 𝑋. (Revised by BJ, 26-Dec-2023.)
(𝑋 ∈ if(𝜑, 𝐴, 𝐵) ↔ if-(𝜑, 𝑋𝐴, 𝑋𝐵))
 
20.15.1.9  Propositional calculus: miscellaneous

Miscellaneous theorems of propositional calculus.

 
Theorembj-imbi12 34391 Uncurried (imported) form of imbi12 350. (Contributed by BJ, 6-May-2019.)
(((𝜑𝜓) ∧ (𝜒𝜃)) → ((𝜑𝜒) ↔ (𝜓𝜃)))
 
Theorembj-biorfi 34392 This should be labeled "biorfi" while the current biorfi 938 should be labeled "biorfri". The dual of biorf 936 is not biantr 806 but iba 531 (and ibar 532). 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 ↔ (𝜑𝜓))
 
Theorembj-falor 34393 Dual of truan 1553 (which has biconditional reversed). (Contributed by BJ, 26-Oct-2019.) (Proof modification is discouraged.)
(𝜑 ↔ (⊥ ∨ 𝜑))
 
Theorembj-falor2 34394 Dual of truan 1553. (Contributed by BJ, 26-Oct-2019.) (Proof modification is discouraged.)
((⊥ ∨ 𝜑) ↔ 𝜑)
 
Theorembj-bibibi 34395 A property of the biconditional. (Contributed by BJ, 26-Oct-2019.) (Proof modification is discouraged.)
(𝜑 ↔ (𝜓 ↔ (𝜑𝜓)))
 
Theorembj-imn3ani 34396 Duplication of bnj1224 32344. Three-fold version of imnani 404. (Contributed by Jonathan Ben-Naim, 3-Jun-2011.) (Revised by BJ, 22-Oct-2019.) (Proof modification is discouraged.)
¬ (𝜑𝜓𝜒)       ((𝜑𝜓) → ¬ 𝜒)
 
Theorembj-andnotim 34397 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) ↔ ((𝜑𝜓) ∨ 𝜒))
 
Theorembj-bi3ant 34398 This used to be in the main part. (Contributed by Wolf Lammen, 14-May-2013.) (Revised by BJ, 14-Jun-2019.)
(𝜑 → (𝜓𝜒))       (((𝜃𝜏) → 𝜑) → (((𝜏𝜃) → 𝜓) → ((𝜃𝜏) → 𝜒)))
 
Theorembj-bisym 34399 This used to be in the main part. (Contributed by Wolf Lammen, 14-May-2013.) (Revised by BJ, 14-Jun-2019.)
(((𝜑𝜓) → (𝜒𝜃)) → (((𝜓𝜑) → (𝜃𝜒)) → ((𝜑𝜓) → (𝜒𝜃))))
 
Theorembj-bixor 34400 Equivalence of two ternary operations. Note the identical order and parenthesizing of the three arguments in both expressions. (Contributed by BJ, 31-Dec-2023.)
((𝜑 ↔ (𝜓𝜒)) ↔ (𝜑 ⊻ (𝜓𝜒)))
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206 20501-20600 207 20601-20700 208 20701-20800 209 20801-20900 210 20901-21000 211 21001-21100 212 21101-21200 213 21201-21300 214 21301-21400 215 21401-21500 216 21501-21600 217 21601-21700 218 21701-21800 219 21801-21900 220 21901-22000 221 22001-22100 222 22101-22200 223 22201-22300 224 22301-22400 225 22401-22500 226 22501-22600 227 22601-22700 228 22701-22800 229 22801-22900 230 22901-23000 231 23001-23100 232 23101-23200 233 23201-23300 234 23301-23400 235 23401-23500 236 23501-23600 237 23601-23700 238 23701-23800 239 23801-23900 240 23901-24000 241 24001-24100 242 24101-24200 243 24201-24300 244 24301-24400 245 24401-24500 246 24501-24600 247 24601-24700 248 24701-24800 249 24801-24900 250 24901-25000 251 25001-25100 252 25101-25200 253 25201-25300 254 25301-25400 255 25401-25500 256 25501-25600 257 25601-25700 258 25701-25800 259 25801-25900 260 25901-26000 261 26001-26100 262 26101-26200 263 26201-26300 264 26301-26400 265 26401-26500 266 26501-26600 267 26601-26700 268 26701-26800 269 26801-26900 270 26901-27000 271 27001-27100 272 27101-27200 273 27201-27300 274 27301-27400 275 27401-27500 276 27501-27600 277 27601-27700 278 27701-27800 279 27801-27900 280 27901-28000 281 28001-28100 282 28101-28200 283 28201-28300 284 28301-28400 285 28401-28500 286 28501-28600 287 28601-28700 288 28701-28800 289 28801-28900 290 28901-29000 291 29001-29100 292 29101-29200 293 29201-29300 294 29301-29400 295 29401-29500 296 29501-29600 297 29601-29700 298 29701-29800 299 29801-29900 300 29901-30000 301 30001-30100 302 30101-30200 303 30201-30300 304 30301-30400 305 30401-30500 306 30501-30600 307 30601-30700 308 30701-30800 309 30801-30900 310 30901-31000 311 31001-31100 312 31101-31200 313 31201-31300 314 31301-31400 315 31401-31500 316 31501-31600 317 31601-31700 318 31701-31800 319 31801-31900 320 31901-32000 321 32001-32100 322 32101-32200 323 32201-32300 324 32301-32400 325 32401-32500 326 32501-32600 327 32601-32700 328 32701-32800 329 32801-32900 330 32901-33000 331 33001-33100 332 33101-33200 333 33201-33300 334 33301-33400 335 33401-33500 336 33501-33600 337 33601-33700 338 33701-33800 339 33801-33900 340 33901-34000 341 34001-34100 342 34101-34200 343 34201-34300 344 34301-34400 345 34401-34500 346 34501-34600 347 34601-34700 348 34701-34800 349 34801-34900 350 34901-35000 351 35001-35100 352 35101-35200 353 35201-35300 354 35301-35400 355 35401-35500 356 35501-35600 357 35601-35700 358 35701-35800 359 35801-35900 360 35901-36000 361 36001-36100 362 36101-36200 363 36201-36300 364 36301-36400 365 36401-36500 366 36501-36600 367 36601-36700 368 36701-36800 369 36801-36900 370 36901-37000 371 37001-37100 372 37101-37200 373 37201-37300 374 37301-37400 375 37401-37500 376 37501-37600 377 37601-37700 378 37701-37800 379 37801-37900 380 37901-38000 381 38001-38100 382 38101-38200 383 38201-38300 384 38301-38400 385 38401-38500 386 38501-38600 387 38601-38700 388 38701-38800 389 38801-38900 390 38901-39000 391 39001-39100 392 39101-39200 393 39201-39300 394 39301-39400 395 39401-39500 396 39501-39600 397 39601-39700 398 39701-39800 399 39801-39900 400 39901-40000 401 40001-40100 402 40101-40200 403 40201-40300 404 40301-40400 405 40401-40500 406 40501-40600 407 40601-40700 408 40701-40800 409 40801-40900 410 40901-41000 411 41001-41100 412 41101-41200 413 41201-41300 414 41301-41400 415 41401-41500 416 41501-41600 417 41601-41700 418 41701-41800 419 41801-41900 420 41901-42000 421 42001-42100 422 42101-42200 423 42201-42300 424 42301-42400 425 42401-42500 426 42501-42600 427 42601-42700 428 42701-42800 429 42801-42900 430 42901-43000 431 43001-43100 432 43101-43200 433 43201-43300 434 43301-43400 435 43401-43500 436 43501-43600 437 43601-43700 438 43701-43800 439 43801-43900 440 43901-44000 441 44001-44100 442 44101-44200 443 44201-44300 444 44301-44400 445 44401-44500 446 44501-44600 447 44601-44700 448 44701-44800 449 44801-44900 450 44901-45000 451 45001-45100 452 45101-45200 453 45201-45300 454 45301-45400 455 45401-45500 456 45501-45600 457 45601-45700 458 45701-45800 459 45801-45900 460 45901-45946
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