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Most recent proofs    These are the 100 (Unicode, GIF) or 1000 (Unicode, GIF) most recent proofs in the iset.mm database for the Intuitionistic Logic Explorer. The iset.mm database is maintained on GitHub with master (stable) and develop (development) versions. This page was created from the commit given on the MPE Most Recent Proofs page. The database from that commit is also available here: iset.mm.

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Last updated on 13-Oct-2025 at 6:51 AM ET.
Recent Additions to the Intuitionistic Logic Explorer
DateLabelDescription
Theorem
 
6-Oct-2025dvconstss 14877 Derivative of a constant function defined on an open set. (Contributed by Jim Kingdon, 6-Oct-2025.)
(𝜑𝑆 ∈ {ℝ, ℂ})    &   𝐽 = (𝐾t 𝑆)    &   𝐾 = (MetOpen‘(abs ∘ − ))    &   (𝜑𝑋𝐽)    &   (𝜑𝐴 ∈ ℂ)       (𝜑 → (𝑆 D (𝑋 × {𝐴})) = (𝑋 × {0}))
 
3-Oct-2025dvidre 14876 Real derivative of the identity function. (Contributed by Jim Kingdon, 3-Oct-2025.)
(ℝ D ( I ↾ ℝ)) = (ℝ × {1})
 
3-Oct-2025dvconstre 14875 Real derivative of a constant function. (Contributed by Jim Kingdon, 3-Oct-2025.)
(𝐴 ∈ ℂ → (ℝ D (ℝ × {𝐴})) = (ℝ × {0}))
 
3-Oct-2025dvidsslem 14872 Lemma for dvconstss 14877. Analogue of dvidlemap 14870 where 𝐹 is defined on an open subset of the real or complex numbers. (Contributed by Jim Kingdon, 3-Oct-2025.)
(𝜑𝑆 ∈ {ℝ, ℂ})    &   𝐽 = (𝐾t 𝑆)    &   𝐾 = (MetOpen‘(abs ∘ − ))    &   (𝜑𝐹:𝑋⟶ℂ)    &   (𝜑𝑋𝐽)    &   ((𝜑 ∧ (𝑥𝑋𝑧𝑋𝑧 # 𝑥)) → (((𝐹𝑧) − (𝐹𝑥)) / (𝑧𝑥)) = 𝐵)    &   𝐵 ∈ ℂ       (𝜑 → (𝑆 D 𝐹) = (𝑋 × {𝐵}))
 
3-Oct-2025dvidrelem 14871 Lemma for dvidre 14876 and dvconstre 14875. Analogue of dvidlemap 14870 for real numbers rather than complex numbers. (Contributed by Jim Kingdon, 3-Oct-2025.)
(𝜑𝐹:ℝ⟶ℂ)    &   ((𝜑 ∧ (𝑥 ∈ ℝ ∧ 𝑧 ∈ ℝ ∧ 𝑧 # 𝑥)) → (((𝐹𝑧) − (𝐹𝑥)) / (𝑧𝑥)) = 𝐵)    &   𝐵 ∈ ℂ       (𝜑 → (ℝ D 𝐹) = (ℝ × {𝐵}))
 
28-Sep-2025metuex 14054 Applying metUnif yields a set. (Contributed by Jim Kingdon, 28-Sep-2025.)
(𝐴𝑉 → (metUnif‘𝐴) ∈ V)
 
28-Sep-2025cndsex 14052 The standard distance function on the complex numbers is a set. (Contributed by Jim Kingdon, 28-Sep-2025.)
(abs ∘ − ) ∈ V
 
25-Sep-2025cntopex 14053 The standard topology on the complex numbers is a set. (Contributed by Jim Kingdon, 25-Sep-2025.)
(MetOpen‘(abs ∘ − )) ∈ V
 
24-Sep-2025mopnset 14051 Getting a set by applying MetOpen. (Contributed by Jim Kingdon, 24-Sep-2025.)
(𝐷𝑉 → (MetOpen‘𝐷) ∈ V)
 
24-Sep-2025blfn 14050 The ball function has universal domain. (Contributed by Jim Kingdon, 24-Sep-2025.)
ball Fn V
 
22-Sep-2025plycjlemc 14938 Lemma for plycj 14939. (Contributed by Mario Carneiro, 24-Jul-2014.) (Revised by Jim Kingdon, 22-Sep-2025.)
(𝜑𝑁 ∈ ℕ0)    &   𝐺 = ((∗ ∘ 𝐹) ∘ ∗)    &   (𝜑𝐴:ℕ0⟶(𝑆 ∪ {0}))    &   (𝜑𝐹 = (𝑧 ∈ ℂ ↦ Σ𝑘 ∈ (0...𝑁)((𝐴𝑘) · (𝑧𝑘))))    &   (𝜑𝐹 ∈ (Poly‘𝑆))       (𝜑𝐺 = (𝑧 ∈ ℂ ↦ Σ𝑘 ∈ (0...𝑁)(((∗ ∘ 𝐴)‘𝑘) · (𝑧𝑘))))
 
20-Sep-2025plycolemc 14936 Lemma for plyco 14937. The result expressed as a sum, with a degree and coefficients for 𝐹 specified as hypotheses. (Contributed by Jim Kingdon, 20-Sep-2025.)
(𝜑𝐹 ∈ (Poly‘𝑆))    &   (𝜑𝐺 ∈ (Poly‘𝑆))    &   ((𝜑 ∧ (𝑥𝑆𝑦𝑆)) → (𝑥 + 𝑦) ∈ 𝑆)    &   ((𝜑 ∧ (𝑥𝑆𝑦𝑆)) → (𝑥 · 𝑦) ∈ 𝑆)    &   (𝜑𝑁 ∈ ℕ0)    &   (𝜑𝐴:ℕ0⟶(𝑆 ∪ {0}))    &   (𝜑 → (𝐴 “ (ℤ‘(𝑁 + 1))) = {0})    &   (𝜑𝐹 = (𝑥 ∈ ℂ ↦ Σ𝑘 ∈ (0...𝑁)((𝐴𝑘) · (𝑥𝑘))))       (𝜑 → (𝑧 ∈ ℂ ↦ Σ𝑘 ∈ (0...𝑁)((𝐴𝑘) · ((𝐺𝑧)↑𝑘))) ∈ (Poly‘𝑆))
 
16-Sep-2025lgsquadlemofi 15233 Lemma for lgsquad 15237. There are finitely many members of 𝑆 with odd first part. (Contributed by Jim Kingdon, 16-Sep-2025.)
(𝜑𝑃 ∈ (ℙ ∖ {2}))    &   (𝜑𝑄 ∈ (ℙ ∖ {2}))    &   (𝜑𝑃𝑄)    &   𝑀 = ((𝑃 − 1) / 2)    &   𝑁 = ((𝑄 − 1) / 2)    &   𝑆 = {⟨𝑥, 𝑦⟩ ∣ ((𝑥 ∈ (1...𝑀) ∧ 𝑦 ∈ (1...𝑁)) ∧ (𝑦 · 𝑃) < (𝑥 · 𝑄))}       (𝜑 → {𝑧𝑆 ∣ ¬ 2 ∥ (1st𝑧)} ∈ Fin)
 
16-Sep-2025lgsquadlemsfi 15232 Lemma for lgsquad 15237. 𝑆 is finite. (Contributed by Jim Kingdon, 16-Sep-2025.)
(𝜑𝑃 ∈ (ℙ ∖ {2}))    &   (𝜑𝑄 ∈ (ℙ ∖ {2}))    &   (𝜑𝑃𝑄)    &   𝑀 = ((𝑃 − 1) / 2)    &   𝑁 = ((𝑄 − 1) / 2)    &   𝑆 = {⟨𝑥, 𝑦⟩ ∣ ((𝑥 ∈ (1...𝑀) ∧ 𝑦 ∈ (1...𝑁)) ∧ (𝑦 · 𝑃) < (𝑥 · 𝑄))}       (𝜑𝑆 ∈ Fin)
 
16-Sep-2025opabfi 6994 Finiteness of an ordered pair abstraction which is a decidable subset of finite sets. (Contributed by Jim Kingdon, 16-Sep-2025.)
𝑆 = {⟨𝑥, 𝑦⟩ ∣ ((𝑥𝐴𝑦𝐵) ∧ 𝜓)}    &   (𝜑𝐴 ∈ Fin)    &   (𝜑𝐵 ∈ Fin)    &   (𝜑 → ∀𝑥𝐴𝑦𝐵 DECID 𝜓)       (𝜑𝑆 ∈ Fin)
 
13-Sep-2025uchoice 6192 Principle of unique choice. This is also called non-choice. The name choice results in its similarity to something like acfun 7269 (with the key difference being the change of to ∃!) but unique choice in fact follows from the axiom of collection and our other axioms. This is somewhat similar to Corollary 3.9.2 of [HoTT], p. (varies) but is better described by the paragraph at the end of Section 3.9 which starts "A similar issue arises in set-theoretic mathematics". (Contributed by Jim Kingdon, 13-Sep-2025.)
((𝐴𝑉 ∧ ∀𝑥𝐴 ∃!𝑦𝜑) → ∃𝑓(𝑓 Fn 𝐴 ∧ ∀𝑥𝐴 [(𝑓𝑥) / 𝑦]𝜑))
 
11-Sep-2025expghmap 14106 Exponentiation is a group homomorphism from addition to multiplication. (Contributed by Mario Carneiro, 18-Jun-2015.) (Revised by AV, 10-Jun-2019.) (Revised by Jim Kingdon, 11-Sep-2025.)
𝑀 = (mulGrp‘ℂfld)    &   𝑈 = (𝑀s {𝑧 ∈ ℂ ∣ 𝑧 # 0})       ((𝐴 ∈ ℂ ∧ 𝐴 # 0) → (𝑥 ∈ ℤ ↦ (𝐴𝑥)) ∈ (ℤring GrpHom 𝑈))
 
11-Sep-2025cnfldui 14088 The invertible complex numbers are exactly those apart from zero. This is recapb 8692 but expressed in terms of fld. (Contributed by Jim Kingdon, 11-Sep-2025.)
{𝑧 ∈ ℂ ∣ 𝑧 # 0} = (Unit‘ℂfld)
 
9-Sep-2025gsumfzfsumlemm 14086 Lemma for gsumfzfsum 14087. The case where the sum is inhabited. (Contributed by Jim Kingdon, 9-Sep-2025.)
(𝜑𝑁 ∈ (ℤ𝑀))    &   ((𝜑𝑘 ∈ (𝑀...𝑁)) → 𝐵 ∈ ℂ)       (𝜑 → (ℂfld Σg (𝑘 ∈ (𝑀...𝑁) ↦ 𝐵)) = Σ𝑘 ∈ (𝑀...𝑁)𝐵)
 
9-Sep-2025gsumfzfsumlem0 14085 Lemma for gsumfzfsum 14087. The case where the sum is empty. (Contributed by Jim Kingdon, 9-Sep-2025.)
(𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℤ)    &   (𝜑𝑁 < 𝑀)       (𝜑 → (ℂfld Σg (𝑘 ∈ (𝑀...𝑁) ↦ 𝐵)) = Σ𝑘 ∈ (𝑀...𝑁)𝐵)
 
9-Sep-2025gsumfzmhm2 13417 Apply a group homomorphism to a group sum, mapping version with implicit substitution. (Contributed by Mario Carneiro, 5-May-2015.) (Revised by AV, 6-Jun-2019.) (Revised by Jim Kingdon, 9-Sep-2025.)
𝐵 = (Base‘𝐺)    &    0 = (0g𝐺)    &   (𝜑𝐺 ∈ CMnd)    &   (𝜑𝐻 ∈ Mnd)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℤ)    &   (𝜑 → (𝑥𝐵𝐶) ∈ (𝐺 MndHom 𝐻))    &   ((𝜑𝑘 ∈ (𝑀...𝑁)) → 𝑋𝐵)    &   (𝑥 = 𝑋𝐶 = 𝐷)    &   (𝑥 = (𝐺 Σg (𝑘 ∈ (𝑀...𝑁) ↦ 𝑋)) → 𝐶 = 𝐸)       (𝜑 → (𝐻 Σg (𝑘 ∈ (𝑀...𝑁) ↦ 𝐷)) = 𝐸)
 
8-Sep-2025gsumfzmhm 13416 Apply a monoid homomorphism to a group sum. (Contributed by Mario Carneiro, 15-Dec-2014.) (Revised by AV, 6-Jun-2019.) (Revised by Jim Kingdon, 8-Sep-2025.)
𝐵 = (Base‘𝐺)    &    0 = (0g𝐺)    &   (𝜑𝐺 ∈ CMnd)    &   (𝜑𝐻 ∈ Mnd)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℤ)    &   (𝜑𝐾 ∈ (𝐺 MndHom 𝐻))    &   (𝜑𝐹:(𝑀...𝑁)⟶𝐵)       (𝜑 → (𝐻 Σg (𝐾𝐹)) = (𝐾‘(𝐺 Σg 𝐹)))
 
6-Sep-2025gsumfzconst 13414 Sum of a constant series. (Contributed by Mario Carneiro, 19-Dec-2014.) (Revised by Jim Kingdon, 6-Sep-2025.)
𝐵 = (Base‘𝐺)    &    · = (.g𝐺)       ((𝐺 ∈ Mnd ∧ 𝑁 ∈ (ℤ𝑀) ∧ 𝑋𝐵) → (𝐺 Σg (𝑘 ∈ (𝑀...𝑁) ↦ 𝑋)) = (((𝑁𝑀) + 1) · 𝑋))
 
31-Aug-2025gsumfzmptfidmadd 13412 The sum of two group sums expressed as mappings with finite domain. (Contributed by AV, 23-Jul-2019.) (Revised by Jim Kingdon, 31-Aug-2025.)
𝐵 = (Base‘𝐺)    &    + = (+g𝐺)    &   (𝜑𝐺 ∈ CMnd)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℤ)    &   ((𝜑𝑥 ∈ (𝑀...𝑁)) → 𝐶𝐵)    &   ((𝜑𝑥 ∈ (𝑀...𝑁)) → 𝐷𝐵)    &   𝐹 = (𝑥 ∈ (𝑀...𝑁) ↦ 𝐶)    &   𝐻 = (𝑥 ∈ (𝑀...𝑁) ↦ 𝐷)       (𝜑 → (𝐺 Σg (𝑥 ∈ (𝑀...𝑁) ↦ (𝐶 + 𝐷))) = ((𝐺 Σg 𝐹) + (𝐺 Σg 𝐻)))
 
30-Aug-2025gsumfzsubmcl 13411 Closure of a group sum in a submonoid. (Contributed by Mario Carneiro, 10-Jan-2015.) (Revised by AV, 3-Jun-2019.) (Revised by Jim Kingdon, 30-Aug-2025.)
(𝜑𝐺 ∈ Mnd)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℤ)    &   (𝜑𝑆 ∈ (SubMnd‘𝐺))    &   (𝜑𝐹:(𝑀...𝑁)⟶𝑆)       (𝜑 → (𝐺 Σg 𝐹) ∈ 𝑆)
 
30-Aug-2025seqm1g 10548 Value of the sequence builder function at a successor. (Contributed by Mario Carneiro, 24-Jun-2013.) (Revised by Jim Kingdon, 30-Aug-2025.)
(𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ (ℤ‘(𝑀 + 1)))    &   (𝜑+𝑉)    &   (𝜑𝐹𝑊)       (𝜑 → (seq𝑀( + , 𝐹)‘𝑁) = ((seq𝑀( + , 𝐹)‘(𝑁 − 1)) + (𝐹𝑁)))
 
29-Aug-2025seqf1og 10595 Rearrange a sum via an arbitrary bijection on (𝑀...𝑁). (Contributed by Mario Carneiro, 27-Feb-2014.) (Revised by Jim Kingdon, 29-Aug-2025.)
((𝜑 ∧ (𝑥𝑆𝑦𝑆)) → (𝑥 + 𝑦) ∈ 𝑆)    &   ((𝜑 ∧ (𝑥𝐶𝑦𝐶)) → (𝑥 + 𝑦) = (𝑦 + 𝑥))    &   ((𝜑 ∧ (𝑥𝑆𝑦𝑆𝑧𝑆)) → ((𝑥 + 𝑦) + 𝑧) = (𝑥 + (𝑦 + 𝑧)))    &   (𝜑𝑁 ∈ (ℤ𝑀))    &   (𝜑𝐶𝑆)    &   (𝜑+𝑉)    &   (𝜑𝐹:(𝑀...𝑁)–1-1-onto→(𝑀...𝑁))    &   ((𝜑𝑥 ∈ (𝑀...𝑁)) → (𝐺𝑥) ∈ 𝐶)    &   ((𝜑𝑘 ∈ (𝑀...𝑁)) → (𝐻𝑘) = (𝐺‘(𝐹𝑘)))    &   (𝜑𝐺𝑊)    &   (𝜑𝐻𝑋)       (𝜑 → (seq𝑀( + , 𝐻)‘𝑁) = (seq𝑀( + , 𝐺)‘𝑁))
 
25-Aug-2025irrmulap 9716 The product of an irrational with a nonzero rational is irrational. By irrational we mean apart from any rational number. For a similar theorem with not rational in place of irrational, see irrmul 9715. (Contributed by Jim Kingdon, 25-Aug-2025.)
(𝜑𝐴 ∈ ℝ)    &   (𝜑 → ∀𝑞 ∈ ℚ 𝐴 # 𝑞)    &   (𝜑𝐵 ∈ ℚ)    &   (𝜑𝐵 ≠ 0)    &   (𝜑𝑄 ∈ ℚ)       (𝜑 → (𝐴 · 𝐵) # 𝑄)
 
19-Aug-2025seqp1g 10540 Value of the sequence builder function at a successor. (Contributed by Mario Carneiro, 24-Jun-2013.) (Revised by Jim Kingdon, 19-Aug-2025.)
((𝑁 ∈ (ℤ𝑀) ∧ 𝐹𝑉+𝑊) → (seq𝑀( + , 𝐹)‘(𝑁 + 1)) = ((seq𝑀( + , 𝐹)‘𝑁) + (𝐹‘(𝑁 + 1))))
 
19-Aug-2025seq1g 10537 Value of the sequence builder function at its initial value. (Contributed by Mario Carneiro, 24-Jun-2013.) (Revised by Jim Kingdon, 19-Aug-2025.)
((𝑀 ∈ ℤ ∧ 𝐹𝑉+𝑊) → (seq𝑀( + , 𝐹)‘𝑀) = (𝐹𝑀))
 
18-Aug-2025iswrdiz 10924 A zero-based sequence is a word. In iswrdinn0 10922 we can specify a length as an nonnegative integer. However, it will occasionally be helpful to allow a negative length, as well as zero, to specify an empty sequence. (Contributed by Jim Kingdon, 18-Aug-2025.)
((𝑊:(0..^𝐿)⟶𝑆𝐿 ∈ ℤ) → 𝑊 ∈ Word 𝑆)
 
16-Aug-2025gsumfzcl 13074 Closure of a finite group sum. (Contributed by Mario Carneiro, 15-Dec-2014.) (Revised by AV, 3-Jun-2019.) (Revised by Jim Kingdon, 16-Aug-2025.)
𝐵 = (Base‘𝐺)    &    0 = (0g𝐺)    &   (𝜑𝐺 ∈ Mnd)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℤ)    &   (𝜑𝐹:(𝑀...𝑁)⟶𝐵)       (𝜑 → (𝐺 Σg 𝐹) ∈ 𝐵)
 
16-Aug-2025iswrdinn0 10922 A zero-based sequence is a word. (Contributed by Stefan O'Rear, 15-Aug-2015.) (Revised by Mario Carneiro, 26-Feb-2016.) (Revised by Jim Kingdon, 16-Aug-2025.)
((𝑊:(0..^𝐿)⟶𝑆𝐿 ∈ ℕ0) → 𝑊 ∈ Word 𝑆)
 
15-Aug-2025gsumfzz 13070 Value of a group sum over the zero element. (Contributed by Mario Carneiro, 7-Dec-2014.) (Revised by Jim Kingdon, 15-Aug-2025.)
0 = (0g𝐺)       ((𝐺 ∈ Mnd ∧ 𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (𝐺 Σg (𝑘 ∈ (𝑀...𝑁) ↦ 0 )) = 0 )
 
14-Aug-2025gsumfzval 12977 An expression for Σg when summing over a finite set of sequential integers. (Contributed by Jim Kingdon, 14-Aug-2025.)
𝐵 = (Base‘𝐺)    &    0 = (0g𝐺)    &    + = (+g𝐺)    &   (𝜑𝐺𝑉)    &   (𝜑𝑀 ∈ ℤ)    &   (𝜑𝑁 ∈ ℤ)    &   (𝜑𝐹:(𝑀...𝑁)⟶𝐵)       (𝜑 → (𝐺 Σg 𝐹) = if(𝑁 < 𝑀, 0 , (seq𝑀( + , 𝐹)‘𝑁)))
 
13-Aug-2025znidom 14156 The ℤ/n structure is an integral domain when 𝑛 is prime. (Contributed by Mario Carneiro, 15-Jun-2015.) (Revised by Jim Kingdon, 13-Aug-2025.)
𝑌 = (ℤ/nℤ‘𝑁)       (𝑁 ∈ ℙ → 𝑌 ∈ IDomn)
 
12-Aug-2025rrgmex 13760 A structure whose set of left-regular elements is inhabited is a set. (Contributed by Jim Kingdon, 12-Aug-2025.)
𝐸 = (RLReg‘𝑅)       (𝐴𝐸𝑅 ∈ V)
 
10-Aug-2025gausslemma2dlem1cl 15216 Lemma for gausslemma2dlem1 15218. Closure of the body of the definition of 𝑅. (Contributed by Jim Kingdon, 10-Aug-2025.)
(𝜑𝑃 ∈ (ℙ ∖ {2}))    &   𝐻 = ((𝑃 − 1) / 2)    &   𝑅 = (𝑥 ∈ (1...𝐻) ↦ if((𝑥 · 2) < (𝑃 / 2), (𝑥 · 2), (𝑃 − (𝑥 · 2))))    &   (𝜑𝐴 ∈ (1...𝐻))       (𝜑 → if((𝐴 · 2) < (𝑃 / 2), (𝐴 · 2), (𝑃 − (𝐴 · 2))) ∈ ℤ)
 
9-Aug-2025gausslemma2dlem1f1o 15217 Lemma for gausslemma2dlem1 15218. (Contributed by Jim Kingdon, 9-Aug-2025.)
(𝜑𝑃 ∈ (ℙ ∖ {2}))    &   𝐻 = ((𝑃 − 1) / 2)    &   𝑅 = (𝑥 ∈ (1...𝐻) ↦ if((𝑥 · 2) < (𝑃 / 2), (𝑥 · 2), (𝑃 − (𝑥 · 2))))       (𝜑𝑅:(1...𝐻)–1-1-onto→(1...𝐻))
 
7-Aug-2025qdclt 10318 Rational < is decidable. (Contributed by Jim Kingdon, 7-Aug-2025.)
((𝐴 ∈ ℚ ∧ 𝐵 ∈ ℚ) → DECID 𝐴 < 𝐵)
 
22-Jul-2025ivthdich 14832 The intermediate value theorem implies real number dichotomy. Because real number dichotomy (also known as analytic LLPO) is a constructive taboo, this means we will be unable to prove the intermediate value theorem as stated here (although versions with additional conditions, such as ivthinc 14822 for strictly monotonic functions, can be proved).

The proof is via a function which we call the hover function and which is also described in Section 5.1 of [Bauer], p. 493. Consider any real number 𝑧. We want to show that 𝑧 ≤ 0 ∨ 0 ≤ 𝑧. Because of hovercncf 14825, hovera 14826, and hoverb 14827, we are able to apply the intermediate value theorem to get a value 𝑐 such that the hover function at 𝑐 equals 𝑧. By axltwlin 8089, 𝑐 < 1 or 0 < 𝑐, and that leads to 𝑧 ≤ 0 by hoverlt1 14828 or 0 ≤ 𝑧 by hovergt0 14829. (Contributed by Jim Kingdon and Mario Carneiro, 22-Jul-2025.)

(∀𝑓(𝑓 ∈ (ℝ–cn→ℝ) → ∀𝑎 ∈ ℝ ∀𝑏 ∈ ℝ ((𝑎 < 𝑏 ∧ (𝑓𝑎) < 0 ∧ 0 < (𝑓𝑏)) → ∃𝑥 ∈ ℝ (𝑎 < 𝑥𝑥 < 𝑏 ∧ (𝑓𝑥) = 0))) → ∀𝑟 ∈ ℝ ∀𝑠 ∈ ℝ (𝑟𝑠𝑠𝑟))
 
22-Jul-2025dich0 14831 Real number dichotomy stated in terms of two real numbers or a real number and zero. (Contributed by Jim Kingdon, 22-Jul-2025.)
(∀𝑧 ∈ ℝ (𝑧 ≤ 0 ∨ 0 ≤ 𝑧) ↔ ∀𝑥 ∈ ℝ ∀𝑦 ∈ ℝ (𝑥𝑦𝑦𝑥))
 
22-Jul-2025ivthdichlem 14830 Lemma for ivthdich 14832. The result, with a few notational conveniences. (Contributed by Jim Kingdon, 22-Jul-2025.)
𝐹 = (𝑥 ∈ ℝ ↦ sup({inf({𝑥, 0}, ℝ, < ), (𝑥 − 1)}, ℝ, < ))    &   (𝜑𝑍 ∈ ℝ)    &   (𝜑 → ∀𝑓(𝑓 ∈ (ℝ–cn→ℝ) → ∀𝑎 ∈ ℝ ∀𝑏 ∈ ℝ ((𝑎 < 𝑏 ∧ (𝑓𝑎) < 0 ∧ 0 < (𝑓𝑏)) → ∃𝑥 ∈ ℝ (𝑎 < 𝑥𝑥 < 𝑏 ∧ (𝑓𝑥) = 0))))       (𝜑 → (𝑍 ≤ 0 ∨ 0 ≤ 𝑍))
 
22-Jul-2025hovergt0 14829 The hover function evaluated at a point greater than zero. (Contributed by Jim Kingdon, 22-Jul-2025.)
𝐹 = (𝑥 ∈ ℝ ↦ sup({inf({𝑥, 0}, ℝ, < ), (𝑥 − 1)}, ℝ, < ))       ((𝐶 ∈ ℝ ∧ 0 < 𝐶) → 0 ≤ (𝐹𝐶))
 
22-Jul-2025hoverlt1 14828 The hover function evaluated at a point less than one. (Contributed by Jim Kingdon, 22-Jul-2025.)
𝐹 = (𝑥 ∈ ℝ ↦ sup({inf({𝑥, 0}, ℝ, < ), (𝑥 − 1)}, ℝ, < ))       ((𝐶 ∈ ℝ ∧ 𝐶 < 1) → (𝐹𝐶) ≤ 0)
 
21-Jul-2025hoverb 14827 A point at which the hover function is greater than a given value. (Contributed by Jim Kingdon, 21-Jul-2025.)
𝐹 = (𝑥 ∈ ℝ ↦ sup({inf({𝑥, 0}, ℝ, < ), (𝑥 − 1)}, ℝ, < ))       (𝑍 ∈ ℝ → 𝑍 < (𝐹‘(𝑍 + 2)))
 
21-Jul-2025hovera 14826 A point at which the hover function is less than a given value. (Contributed by Jim Kingdon, 21-Jul-2025.)
𝐹 = (𝑥 ∈ ℝ ↦ sup({inf({𝑥, 0}, ℝ, < ), (𝑥 − 1)}, ℝ, < ))       (𝑍 ∈ ℝ → (𝐹‘(𝑍 − 1)) < 𝑍)
 
21-Jul-2025rexeqtrrdv 2701 Substitution of equal classes into a restricted existential quantifier. (Contributed by Matthew House, 21-Jul-2025.)
(𝜑 → ∃𝑥𝐴 𝜓)    &   (𝜑𝐵 = 𝐴)       (𝜑 → ∃𝑥𝐵 𝜓)
 
21-Jul-2025raleqtrrdv 2700 Substitution of equal classes into a restricted universal quantifier. (Contributed by Matthew House, 21-Jul-2025.)
(𝜑 → ∀𝑥𝐴 𝜓)    &   (𝜑𝐵 = 𝐴)       (𝜑 → ∀𝑥𝐵 𝜓)
 
21-Jul-2025rexeqtrdv 2699 Substitution of equal classes into a restricted existential quantifier. (Contributed by Matthew House, 21-Jul-2025.)
(𝜑 → ∃𝑥𝐴 𝜓)    &   (𝜑𝐴 = 𝐵)       (𝜑 → ∃𝑥𝐵 𝜓)
 
21-Jul-2025raleqtrdv 2698 Substitution of equal classes into a restricted universal quantifier. (Contributed by Matthew House, 21-Jul-2025.)
(𝜑 → ∀𝑥𝐴 𝜓)    &   (𝜑𝐴 = 𝐵)       (𝜑 → ∀𝑥𝐵 𝜓)
 
20-Jul-2025hovercncf 14825 The hover function is continuous. By hover function, we mean a a function which starts out as a line of slope one, is constant at zero from zero to one, and then resumes as a slope of one. (Contributed by Jim Kingdon, 20-Jul-2025.)
𝐹 = (𝑥 ∈ ℝ ↦ sup({inf({𝑥, 0}, ℝ, < ), (𝑥 − 1)}, ℝ, < ))       𝐹 ∈ (ℝ–cn→ℝ)
 
19-Jul-2025mincncf 14795 The minimum of two continuous real functions is continuous. (Contributed by Jim Kingdon, 19-Jul-2025.)
(𝜑 → (𝑥𝑋𝐴) ∈ (𝑋cn→ℝ))    &   (𝜑 → (𝑥𝑋𝐵) ∈ (𝑋cn→ℝ))       (𝜑 → (𝑥𝑋 ↦ inf({𝐴, 𝐵}, ℝ, < )) ∈ (𝑋cn→ℝ))
 
18-Jul-2025maxcncf 14794 The maximum of two continuous real functions is continuous. (Contributed by Jim Kingdon, 18-Jul-2025.)
(𝜑 → (𝑥𝑋𝐴) ∈ (𝑋cn→ℝ))    &   (𝜑 → (𝑥𝑋𝐵) ∈ (𝑋cn→ℝ))       (𝜑 → (𝑥𝑋 ↦ sup({𝐴, 𝐵}, ℝ, < )) ∈ (𝑋cn→ℝ))
 
14-Jul-2025xnn0nnen 10511 The set of extended nonnegative integers is equinumerous to the set of natural numbers. (Contributed by Jim Kingdon, 14-Jul-2025.)
0* ≈ ℕ
 
12-Jul-2025nninfninc 7184 All values beyond a zero in an sequence are zero. This is another way of stating that elements of are nonincreasing. (Contributed by Jim Kingdon, 12-Jul-2025.)
(𝜑𝐴 ∈ ℕ)    &   (𝜑𝑋 ∈ ω)    &   (𝜑𝑌 ∈ ω)    &   (𝜑𝑋𝑌)    &   (𝜑 → (𝐴𝑋) = ∅)       (𝜑 → (𝐴𝑌) = ∅)
 
10-Jul-2025nninfctlemfo 12180 Lemma for nninfct 12181. (Contributed by Jim Kingdon, 10-Jul-2025.)
𝐺 = frec((𝑥 ∈ ℤ ↦ (𝑥 + 1)), 0)    &   𝐹 = (𝑛 ∈ ω ↦ (𝑖 ∈ ω ↦ if(𝑖𝑛, 1o, ∅)))    &   𝐼 = ((𝐹𝐺) ∪ {⟨+∞, (ω × {1o})⟩})       (ω ∈ Omni → 𝐼:ℕ0*onto→ℕ)
 
8-Jul-2025nnnninfen 15581 Equinumerosity of the natural numbers and is equivalent to the Limited Principle of Omniscience (LPO). Remark in Section 1.1 of [Pradic2025], p. 2. (Contributed by Jim Kingdon, 8-Jul-2025.)
(ω ≈ ℕ ↔ ω ∈ Omni)
 
8-Jul-2025nninfct 12181 The limited principle of omniscience (LPO) implies that is countable. (Contributed by Jim Kingdon, 8-Jul-2025.)
(ω ∈ Omni → ∃𝑓 𝑓:ω–onto→(ℕ ⊔ 1o))
 
8-Jul-2025nninfinf 10517 is infinte. (Contributed by Jim Kingdon, 8-Jul-2025.)
ω ≼ ℕ
 
7-Jul-2025ivthreinc 14824 Restating the intermediate value theorem. Given a hypothesis stating the intermediate value theorem (in a strong form which is not provable given our axioms alone), provide a conclusion similar to the theorem as stated in the Metamath Proof Explorer (which is also similar to how we state the theorem for a strictly monotonic function at ivthinc 14822). Being able to have a hypothesis stating the intermediate value theorem will be helpful when it comes time to show that it implies a constructive taboo. This version of the theorem requires that the function 𝐹 is continuous on the entire real line, not just (𝐴[,]𝐵) which may be an unnecessary condition but which is sufficient for the way we want to use it. (Contributed by Jim Kingdon, 7-Jul-2025.)
(𝜑𝐴 ∈ ℝ)    &   (𝜑𝐵 ∈ ℝ)    &   (𝜑𝑈 ∈ ℝ)    &   (𝜑𝐴 < 𝐵)    &   (𝜑𝐹 ∈ (ℝ–cn→ℝ))    &   (𝜑 → ((𝐹𝐴) < 𝑈𝑈 < (𝐹𝐵)))    &   (𝜑 → ∀𝑓(𝑓 ∈ (ℝ–cn→ℝ) → ∀𝑎 ∈ ℝ ∀𝑏 ∈ ℝ ((𝑎 < 𝑏 ∧ (𝑓𝑎) < 0 ∧ 0 < (𝑓𝑏)) → ∃𝑥 ∈ ℝ (𝑎 < 𝑥𝑥 < 𝑏 ∧ (𝑓𝑥) = 0))))       (𝜑 → ∃𝑐 ∈ (𝐴(,)𝐵)(𝐹𝑐) = 𝑈)
 
28-Jun-2025fngsum 12974 Iterated sum has a universal domain. (Contributed by Jim Kingdon, 28-Jun-2025.)
Σg Fn (V × V)
 
28-Jun-2025iotaexel 5879 Set existence of an iota expression in which all values are contained within a set. (Contributed by Jim Kingdon, 28-Jun-2025.)
((𝐴𝑉 ∧ ∀𝑥(𝜑𝑥𝐴)) → (℩𝑥𝜑) ∈ V)
 
27-Jun-2025df-igsum 12873 Define a finite group sum (also called "iterated sum") of a structure.

Given 𝐺 Σg 𝐹 where 𝐹:𝐴⟶(Base‘𝐺), the set of indices is 𝐴 and the values are given by 𝐹 at each index. A group sum over a multiplicative group may be viewed as a product. The definition is meaningful in different contexts, depending on the size of the index set 𝐴 and each demanding different properties of 𝐺.

1. If 𝐴 = ∅ and 𝐺 has an identity element, then the sum equals this identity.

2. If 𝐴 = (𝑀...𝑁) and 𝐺 is any magma, then the sum is the sum of the elements, evaluated left-to-right, i.e., ((𝐹‘1) + (𝐹‘2)) + (𝐹‘3), etc.

3. This definition does not handle other cases.

(Contributed by FL, 5-Sep-2010.) (Revised by Mario Carneiro, 7-Dec-2014.) (Revised by Jim Kingdon, 27-Jun-2025.)

Σg = (𝑤 ∈ V, 𝑓 ∈ V ↦ (℩𝑥((dom 𝑓 = ∅ ∧ 𝑥 = (0g𝑤)) ∨ ∃𝑚𝑛 ∈ (ℤ𝑚)(dom 𝑓 = (𝑚...𝑛) ∧ 𝑥 = (seq𝑚((+g𝑤), 𝑓)‘𝑛)))))
 
20-Jun-2025opprnzrbg 13684 The opposite of a nonzero ring is nonzero, bidirectional form of opprnzr 13685. (Contributed by SN, 20-Jun-2025.)
𝑂 = (oppr𝑅)       (𝑅𝑉 → (𝑅 ∈ NzRing ↔ 𝑂 ∈ NzRing))
 
16-Jun-2025fnpsr 14164 The multivariate power series constructor has a universal domain. (Contributed by Jim Kingdon, 16-Jun-2025.)
mPwSer Fn (V × V)
 
14-Jun-2025basm 12682 A structure whose base is inhabited is inhabited. (Contributed by Jim Kingdon, 14-Jun-2025.)
𝐵 = (Base‘𝐺)       (𝐴𝐵 → ∃𝑗 𝑗𝐺)
 
14-Jun-2025elfvm 5588 If a function value has a member, the function is inhabited. (Contributed by Jim Kingdon, 14-Jun-2025.)
(𝐴 ∈ (𝐹𝐵) → ∃𝑗 𝑗𝐹)
 
6-Jun-2025pcxqcl 12453 The general prime count function is an integer or infinite. (Contributed by Jim Kingdon, 6-Jun-2025.)
((𝑃 ∈ ℙ ∧ 𝑁 ∈ ℚ) → ((𝑃 pCnt 𝑁) ∈ ℤ ∨ (𝑃 pCnt 𝑁) = +∞))
 
5-Jun-2025xqltnle 10339 "Less than" expressed in terms of "less than or equal to", for extended numbers which are rational or +∞. We have not yet had enough usage of such numbers to warrant fully developing the concept, as in 0* or *, so for now we just have a handful of theorems for what we need. (Contributed by Jim Kingdon, 5-Jun-2025.)
(((𝐴 ∈ ℚ ∨ 𝐴 = +∞) ∧ (𝐵 ∈ ℚ ∨ 𝐵 = +∞)) → (𝐴 < 𝐵 ↔ ¬ 𝐵𝐴))
 
5-Jun-2025ceqsexv2d 2800 Elimination of an existential quantifier, using implicit substitution. (Contributed by Thierry Arnoux, 10-Sep-2016.) Shorten, reduce dv conditions. (Revised by Wolf Lammen, 5-Jun-2025.) (Proof shortened by SN, 5-Jun-2025.)
𝐴 ∈ V    &   (𝑥 = 𝐴 → (𝜑𝜓))    &   𝜓       𝑥𝜑
 
30-May-20254sqexercise2 12540 Exercise which may help in understanding the proof of 4sqlemsdc 12541. (Contributed by Jim Kingdon, 30-May-2025.)
𝑆 = {𝑛 ∣ ∃𝑥 ∈ ℤ ∃𝑦 ∈ ℤ 𝑛 = ((𝑥↑2) + (𝑦↑2))}       (𝐴 ∈ ℕ0DECID 𝐴𝑆)
 
27-May-2025iotaexab 5234 Existence of the class when all the possible values are contained in a set. (Contributed by Jim Kingdon, 27-May-2025.)
({𝑥𝜑} ∈ 𝑉 → (℩𝑥𝜑) ∈ V)
 
25-May-20254sqlemsdc 12541 Lemma for 4sq 12551. The property of being the sum of four squares is decidable.

The proof involves showing that (for a particular 𝐴) there are only a finite number of possible ways that it could be the sum of four squares, so checking each of those possibilities in turn decides whether the number is the sum of four squares. If this proof is hard to follow, especially because of its length, the simplified versions at 4sqexercise1 12539 and 4sqexercise2 12540 may help clarify, as they are using very much the same techniques on simplified versions of this lemma. (Contributed by Jim Kingdon, 25-May-2025.)

𝑆 = {𝑛 ∣ ∃𝑥 ∈ ℤ ∃𝑦 ∈ ℤ ∃𝑧 ∈ ℤ ∃𝑤 ∈ ℤ 𝑛 = (((𝑥↑2) + (𝑦↑2)) + ((𝑧↑2) + (𝑤↑2)))}       (𝐴 ∈ ℕ0DECID 𝐴𝑆)
 
25-May-20254sqexercise1 12539 Exercise which may help in understanding the proof of 4sqlemsdc 12541. (Contributed by Jim Kingdon, 25-May-2025.)
𝑆 = {𝑛 ∣ ∃𝑥 ∈ ℤ 𝑛 = (𝑥↑2)}       (𝐴 ∈ ℕ0DECID 𝐴𝑆)
 
24-May-20254sqleminfi 12538 Lemma for 4sq 12551. 𝐴 ∩ ran 𝐹 is finite. (Contributed by Jim Kingdon, 24-May-2025.)
(𝜑𝑁 ∈ ℕ)    &   (𝜑𝑃 ∈ ℕ)    &   𝐴 = {𝑢 ∣ ∃𝑚 ∈ (0...𝑁)𝑢 = ((𝑚↑2) mod 𝑃)}    &   𝐹 = (𝑣𝐴 ↦ ((𝑃 − 1) − 𝑣))       (𝜑 → (𝐴 ∩ ran 𝐹) ∈ Fin)
 
24-May-20254sqlemffi 12537 Lemma for 4sq 12551. ran 𝐹 is finite. (Contributed by Jim Kingdon, 24-May-2025.)
(𝜑𝑁 ∈ ℕ)    &   (𝜑𝑃 ∈ ℕ)    &   𝐴 = {𝑢 ∣ ∃𝑚 ∈ (0...𝑁)𝑢 = ((𝑚↑2) mod 𝑃)}    &   𝐹 = (𝑣𝐴 ↦ ((𝑃 − 1) − 𝑣))       (𝜑 → ran 𝐹 ∈ Fin)
 
24-May-20254sqlemafi 12536 Lemma for 4sq 12551. 𝐴 is finite. (Contributed by Jim Kingdon, 24-May-2025.)
(𝜑𝑁 ∈ ℕ)    &   (𝜑𝑃 ∈ ℕ)    &   𝐴 = {𝑢 ∣ ∃𝑚 ∈ (0...𝑁)𝑢 = ((𝑚↑2) mod 𝑃)}       (𝜑𝐴 ∈ Fin)
 
24-May-2025infidc 6995 The intersection of two sets is finite if one of them is and the other is decidable. (Contributed by Jim Kingdon, 24-May-2025.)
((𝐴 ∈ Fin ∧ ∀𝑥𝐴 DECID 𝑥𝐵) → (𝐴𝐵) ∈ Fin)
 
19-May-2025zrhex 14120 Set existence for ℤRHom. (Contributed by Jim Kingdon, 19-May-2025.)
𝐿 = (ℤRHom‘𝑅)       (𝑅𝑉𝐿 ∈ V)
 
16-May-2025rhmex 13656 Set existence for ring homomorphism. (Contributed by Jim Kingdon, 16-May-2025.)
((𝑅𝑉𝑆𝑊) → (𝑅 RingHom 𝑆) ∈ V)
 
15-May-2025ghmex 13328 The set of group homomorphisms exists. (Contributed by Jim Kingdon, 15-May-2025.)
((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → (𝑆 GrpHom 𝑇) ∈ V)
 
15-May-2025mhmex 13037 The set of monoid homomorphisms exists. (Contributed by Jim Kingdon, 15-May-2025.)
((𝑆 ∈ Mnd ∧ 𝑇 ∈ Mnd) → (𝑆 MndHom 𝑇) ∈ V)
 
14-May-2025idomcringd 13777 An integral domain is a commutative ring with unity. (Contributed by Thierry Arnoux, 4-May-2025.) (Proof shortened by SN, 14-May-2025.)
(𝜑𝑅 ∈ IDomn)       (𝜑𝑅 ∈ CRing)
 
6-May-2025rrgnz 13767 In a nonzero ring, the zero is a left zero divisor (that is, not a left-regular element). (Contributed by Thierry Arnoux, 6-May-2025.)
𝐸 = (RLReg‘𝑅)    &    0 = (0g𝑅)       (𝑅 ∈ NzRing → ¬ 0𝐸)
 
5-May-2025rngressid 13453 A non-unital ring restricted to its base set is a non-unital ring. It will usually be the original non-unital ring exactly, of course, but to show that needs additional conditions such as those in strressid 12692. (Contributed by Jim Kingdon, 5-May-2025.)
𝐵 = (Base‘𝐺)       (𝐺 ∈ Rng → (𝐺s 𝐵) ∈ Rng)
 
5-May-2025ablressid 13408 A commutative group restricted to its base set is a commutative group. It will usually be the original group exactly, of course, but to show that needs additional conditions such as those in strressid 12692. (Contributed by Jim Kingdon, 5-May-2025.)
𝐵 = (Base‘𝐺)       (𝐺 ∈ Abel → (𝐺s 𝐵) ∈ Abel)
 
29-Apr-2025rlmscabas 13959 Scalars in the ring module have the same base set. (Contributed by Jim Kingdon, 29-Apr-2025.)
(𝑅𝑋 → (Base‘𝑅) = (Base‘(Scalar‘(ringLMod‘𝑅))))
 
29-Apr-2025ressbasid 12691 The trivial structure restriction leaves the base set unchanged. (Contributed by Jim Kingdon, 29-Apr-2025.)
𝐵 = (Base‘𝑊)       (𝑊𝑉 → (Base‘(𝑊s 𝐵)) = 𝐵)
 
28-Apr-2025lssmex 13854 If a linear subspace is inhabited, the class it is built from is a set. (Contributed by Jim Kingdon, 28-Apr-2025.)
𝑆 = (LSubSp‘𝑊)       (𝑈𝑆𝑊 ∈ V)
 
27-Apr-2025cnfldmul 14063 The multiplication operation of the field of complex numbers. (Contributed by Stefan O'Rear, 27-Nov-2014.) (Revised by Mario Carneiro, 6-Oct-2015.) (Revised by Thierry Arnoux, 17-Dec-2017.) (Revised by GG, 27-Apr-2025.)
· = (.r‘ℂfld)
 
27-Apr-2025cnfldadd 14061 The addition operation of the field of complex numbers. (Contributed by Stefan O'Rear, 27-Nov-2014.) (Revised by Mario Carneiro, 6-Oct-2015.) (Revised by Thierry Arnoux, 17-Dec-2017.) (Revised by GG, 27-Apr-2025.)
+ = (+g‘ℂfld)
 
27-Apr-2025lidlex 13972 Existence of the set of left ideals. (Contributed by Jim Kingdon, 27-Apr-2025.)
(𝑊𝑉 → (LIdeal‘𝑊) ∈ V)
 
27-Apr-2025lssex 13853 Existence of a linear subspace. (Contributed by Jim Kingdon, 27-Apr-2025.)
(𝑊𝑉 → (LSubSp‘𝑊) ∈ V)
 
25-Apr-2025rspex 13973 Existence of the ring span. (Contributed by Jim Kingdon, 25-Apr-2025.)
(𝑊𝑉 → (RSpan‘𝑊) ∈ V)
 
25-Apr-2025lspex 13894 Existence of the span of a set of vectors. (Contributed by Jim Kingdon, 25-Apr-2025.)
(𝑊𝑋 → (LSpan‘𝑊) ∈ V)
 
25-Apr-2025eqgex 13294 The left coset equivalence relation exists. (Contributed by Jim Kingdon, 25-Apr-2025.)
((𝐺𝑉𝑆𝑊) → (𝐺 ~QG 𝑆) ∈ V)
 
25-Apr-2025qusex 12911 Existence of a quotient structure. (Contributed by Jim Kingdon, 25-Apr-2025.)
((𝑅𝑉𝑊) → (𝑅 /s ) ∈ V)
 
23-Apr-20251dom1el 15553 If a set is dominated by one, then any two of its elements are equal. (Contributed by Jim Kingdon, 23-Apr-2025.)
((𝐴 ≼ 1o𝐵𝐴𝐶𝐴) → 𝐵 = 𝐶)
 
22-Apr-2025mulgex 13196 Existence of the group multiple operation. (Contributed by Jim Kingdon, 22-Apr-2025.)
(𝐺𝑉 → (.g𝐺) ∈ V)

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