P. 423 of Theorem List - Metamath Proof Explorer

Theorem List for Metamath Proof Explorer - 42201-42300   *Has distinct variable group(s)

Type	Label	Description
Statement
Theorem	aks5lem7 42201*	Lemma for aks5. We clean up the hypotheses compared to aks5lem6 42193. (Contributed by metakunt, 9-Aug-2025.)
⊢ (𝜑 → (♯‘(Base‘𝐾)) ∈ ℕ)    &   ⊢ 𝑃 = (chr‘𝐾)    &   ⊢ (𝜑 → 𝐾 ∈ Field)    &   ⊢ (𝜑 → 𝑃 ∈ ℙ)    &   ⊢ (𝜑 → 𝑅 ∈ ℕ)    &   ⊢ (𝜑 → 𝑁 ∈ (ℤ≥‘3))    &   ⊢ (𝜑 → 𝑃 ∥ 𝑁)    &   ⊢ (𝜑 → (𝑁 gcd 𝑅) = 1)    &   ⊢ 𝐴 = (⌊‘((√‘(ϕ‘𝑅)) · (2 logb 𝑁)))    &   ⊢ (𝜑 → ((2 logb 𝑁)↑2) < ((odℤ‘𝑅)‘𝑁))    &   ⊢ (𝜑 → 𝑅 ∥ ((♯‘(Base‘𝐾)) − 1))    &   ⊢ (𝜑 → ∀𝑎 ∈ (1...𝐴)[(𝑁(.g‘(mulGrp‘𝑆))(𝑋(+g‘𝑆)((ℤRHom‘𝑆)‘𝑎)))](𝑆 ~QG 𝐿) = [((𝑁(.g‘(mulGrp‘𝑆))𝑋)(+g‘𝑆)((ℤRHom‘𝑆)‘𝑎))](𝑆 ~QG 𝐿))    &   ⊢ (𝜑 → ∀𝑏 ∈ (1...𝐴)(𝑏 gcd 𝑁) = 1)    &   ⊢ 𝑆 = (Poly1‘(ℤ/nℤ‘𝑁))    &   ⊢ 𝐿 = ((RSpan‘𝑆)‘{((𝑅(.g‘(mulGrp‘𝑆))𝑋)(-g‘𝑆)(1r‘𝑆))})    &   ⊢ 𝑋 = (var1‘(ℤ/nℤ‘𝑁))    ⇒   ⊢ (𝜑 → 𝑁 = (𝑃↑(𝑃 pCnt 𝑁)))
Theorem	aks5lem8 42202*	Lemma for aks5. Clean up the conclusion. (Contributed by metakunt, 9-Aug-2025.)
⊢ (𝜑 → (♯‘(Base‘𝐾)) ∈ ℕ)    &   ⊢ 𝑃 = (chr‘𝐾)    &   ⊢ (𝜑 → 𝐾 ∈ Field)    &   ⊢ (𝜑 → 𝑃 ∈ ℙ)    &   ⊢ (𝜑 → 𝑅 ∈ ℕ)    &   ⊢ (𝜑 → 𝑁 ∈ (ℤ≥‘3))    &   ⊢ (𝜑 → 𝑃 ∥ 𝑁)    &   ⊢ (𝜑 → (𝑁 gcd 𝑅) = 1)    &   ⊢ 𝐴 = (⌊‘((√‘(ϕ‘𝑅)) · (2 logb 𝑁)))    &   ⊢ (𝜑 → ((2 logb 𝑁)↑2) < ((odℤ‘𝑅)‘𝑁))    &   ⊢ (𝜑 → 𝑅 ∥ ((♯‘(Base‘𝐾)) − 1))    &   ⊢ (𝜑 → ∀𝑎 ∈ (1...𝐴)[(𝑁(.g‘(mulGrp‘𝑆))(𝑋(+g‘𝑆)((ℤRHom‘𝑆)‘𝑎)))](𝑆 ~QG 𝐿) = [((𝑁(.g‘(mulGrp‘𝑆))𝑋)(+g‘𝑆)((ℤRHom‘𝑆)‘𝑎))](𝑆 ~QG 𝐿))    &   ⊢ (𝜑 → ∀𝑏 ∈ (1...𝐴)(𝑏 gcd 𝑁) = 1)    &   ⊢ 𝑆 = (Poly1‘(ℤ/nℤ‘𝑁))    &   ⊢ 𝐿 = ((RSpan‘𝑆)‘{((𝑅(.g‘(mulGrp‘𝑆))𝑋)(-g‘𝑆)(1r‘𝑆))})    &   ⊢ 𝑋 = (var1‘(ℤ/nℤ‘𝑁))    ⇒   ⊢ (𝜑 → ∃𝑝 ∈ ℙ ∃𝑛 ∈ ℕ 𝑁 = (𝑝↑𝑛))
Axiom	ax-exfinfld 42203*	Existence axiom for finite fields, eventually we want to construct them. (Contributed by metakunt, 13-Jul-2025.)
⊢ ∀𝑝 ∈ ℙ ∀𝑛 ∈ ℕ ∃𝑘 ∈ Field ((♯‘(Base‘𝑘)) = (𝑝↑𝑛) ∧ (chr‘𝑘) = 𝑝)
Theorem	exfinfldd 42204*	For any prime 𝑃 and any positive integer 𝑁 there exists a field 𝑘 such that 𝑘 contains 𝑃↑𝑁 elements. (Contributed by metakunt, 13-Jul-2025.)
⊢ (𝜑 → 𝑃 ∈ ℙ)    &   ⊢ (𝜑 → 𝑁 ∈ ℕ)    ⇒   ⊢ (𝜑 → ∃𝑘 ∈ Field ((♯‘(Base‘𝑘)) = (𝑃↑𝑁) ∧ (chr‘𝑘) = 𝑃))
Theorem	aks5 42205*	The AKS Primality test, given an integer 𝑁 greater than or equal to 3, find a coprime 𝑅 such that 𝑅 is big enough. Then, if a bunch of polynomial equalities in the residue ring hold then 𝑁 is a prime power. Currently depends on the axiom ax-exfinfld 42203, since we currently do not have the existence of finite fields in the database. (Contributed by metakunt, 16-Aug-2025.)
⊢ 𝐴 = (⌊‘((√‘(ϕ‘𝑅)) · (2 logb 𝑁)))    &   ⊢ 𝑋 = (var1‘(ℤ/nℤ‘𝑁))    &   ⊢ 𝑆 = (Poly1‘(ℤ/nℤ‘𝑁))    &   ⊢ 𝐿 = ((RSpan‘𝑆)‘{((𝑅(.g‘(mulGrp‘𝑆))𝑋)(-g‘𝑆)(1r‘𝑆))})    &   ⊢ (𝜑 → 𝑁 ∈ (ℤ≥‘3))    &   ⊢ (𝜑 → 𝑅 ∈ ℕ)    &   ⊢ (𝜑 → (𝑁 gcd 𝑅) = 1)    &   ⊢ (𝜑 → ((2 logb 𝑁)↑2) < ((odℤ‘𝑅)‘𝑁))    &   ⊢ (𝜑 → ∀𝑎 ∈ (1...𝐴)[(𝑁(.g‘(mulGrp‘𝑆))(𝑋(+g‘𝑆)((ℤRHom‘𝑆)‘𝑎)))](𝑆 ~QG 𝐿) = [((𝑁(.g‘(mulGrp‘𝑆))𝑋)(+g‘𝑆)((ℤRHom‘𝑆)‘𝑎))](𝑆 ~QG 𝐿))    &   ⊢ (𝜑 → ∀𝑎 ∈ (1...𝐴)(𝑎 gcd 𝑁) = 1)    ⇒   ⊢ (𝜑 → ∃𝑝 ∈ ℙ ∃𝑛 ∈ ℕ 𝑁 = (𝑝↑𝑛))
21.29.9  Permutation results
Theorem	metakunt1 42206*	A is an endomapping. (Contributed by metakunt, 23-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    ⇒   ⊢ (𝜑 → 𝐴:(1...𝑀)⟶(1...𝑀))
Theorem	metakunt2 42207*	A is an endomapping. (Contributed by metakunt, 23-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝑀, 𝐼, if(𝑥 < 𝐼, 𝑥, (𝑥 + 1))))    ⇒   ⊢ (𝜑 → 𝐴:(1...𝑀)⟶(1...𝑀))
Theorem	metakunt3 42208*	Value of A. (Contributed by metakunt, 23-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ (𝜑 → (𝐴‘𝑋) = if(𝑋 = 𝐼, 𝑀, if(𝑋 < 𝐼, 𝑋, (𝑋 − 1))))
Theorem	metakunt4 42209*	Value of A. (Contributed by metakunt, 23-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝑀, 𝐼, if(𝑥 < 𝐼, 𝑥, (𝑥 + 1))))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ (𝜑 → (𝐴‘𝑋) = if(𝑋 = 𝑀, 𝐼, if(𝑋 < 𝐼, 𝑋, (𝑋 + 1))))
Theorem	metakunt5 42210*	C is the left inverse for A. (Contributed by metakunt, 24-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ ((𝜑 ∧ 𝑋 = 𝐼) → (𝐶‘(𝐴‘𝑋)) = 𝑋)
Theorem	metakunt6 42211*	C is the left inverse for A. (Contributed by metakunt, 24-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ ((𝜑 ∧ 𝑋 < 𝐼) → (𝐶‘(𝐴‘𝑋)) = 𝑋)
Theorem	metakunt7 42212*	C is the left inverse for A. (Contributed by metakunt, 24-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ ((𝜑 ∧ 𝐼 < 𝑋) → ((𝐴‘𝑋) = (𝑋 − 1) ∧ ¬ (𝐴‘𝑋) = 𝑀 ∧ ¬ (𝐴‘𝑋) < 𝐼))
Theorem	metakunt8 42213*	C is the left inverse for A. (Contributed by metakunt, 24-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ ((𝜑 ∧ 𝐼 < 𝑋) → (𝐶‘(𝐴‘𝑋)) = 𝑋)
Theorem	metakunt9 42214*	C is the left inverse for A. (Contributed by metakunt, 24-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ (𝜑 → (𝐶‘(𝐴‘𝑋)) = 𝑋)
Theorem	metakunt10 42215*	C is the right inverse for A. (Contributed by metakunt, 24-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ ((𝜑 ∧ 𝑋 = 𝑀) → (𝐴‘(𝐶‘𝑋)) = 𝑋)
Theorem	metakunt11 42216*	C is the right inverse for A. (Contributed by metakunt, 24-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ ((𝜑 ∧ 𝑋 < 𝐼) → (𝐴‘(𝐶‘𝑋)) = 𝑋)
Theorem	metakunt12 42217*	C is the right inverse for A. (Contributed by metakunt, 25-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ ((𝜑 ∧ ¬ (𝑋 = 𝑀 ∨ 𝑋 < 𝐼)) → (𝐴‘(𝐶‘𝑋)) = 𝑋)
Theorem	metakunt13 42218*	C is the right inverse for A. (Contributed by metakunt, 25-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ (𝜑 → (𝐴‘(𝐶‘𝑋)) = 𝑋)
Theorem	metakunt14 42219*	A is a primitive permutation that moves the I-th element to the end and C is its inverse that moves the last element back to the I-th position. (Contributed by metakunt, 25-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    ⇒   ⊢ (𝜑 → (𝐴:(1...𝑀)–1-1-onto→(1...𝑀) ∧ ◡𝐴 = 𝐶))
Theorem	metakunt15 42220*	Construction of another permutation. (Contributed by metakunt, 25-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐹 = (𝑥 ∈ (1...(𝐼 − 1)) ↦ (𝑥 + (𝑀 − 𝐼)))    ⇒   ⊢ (𝜑 → 𝐹:(1...(𝐼 − 1))–1-1-onto→(((𝑀 − 𝐼) + 1)...(𝑀 − 1)))
Theorem	metakunt16 42221*	Construction of another permutation. (Contributed by metakunt, 25-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐹 = (𝑥 ∈ (𝐼...(𝑀 − 1)) ↦ (𝑥 + (1 − 𝐼)))    ⇒   ⊢ (𝜑 → 𝐹:(𝐼...(𝑀 − 1))–1-1-onto→(1...(𝑀 − 𝐼)))
Theorem	metakunt17 42222	The union of three disjoint bijections is a bijection. (Contributed by metakunt, 28-May-2024.)
⊢ (𝜑 → 𝐺:𝐴–1-1-onto→𝑋)    &   ⊢ (𝜑 → 𝐻:𝐵–1-1-onto→𝑌)    &   ⊢ (𝜑 → 𝐼:𝐶–1-1-onto→𝑍)    &   ⊢ (𝜑 → (𝐴 ∩ 𝐵) = ∅)    &   ⊢ (𝜑 → (𝐴 ∩ 𝐶) = ∅)    &   ⊢ (𝜑 → (𝐵 ∩ 𝐶) = ∅)    &   ⊢ (𝜑 → (𝑋 ∩ 𝑌) = ∅)    &   ⊢ (𝜑 → (𝑋 ∩ 𝑍) = ∅)    &   ⊢ (𝜑 → (𝑌 ∩ 𝑍) = ∅)    &   ⊢ (𝜑 → 𝐹 = ((𝐺 ∪ 𝐻) ∪ 𝐼))    &   ⊢ (𝜑 → 𝐷 = ((𝐴 ∪ 𝐵) ∪ 𝐶))    &   ⊢ (𝜑 → 𝑊 = ((𝑋 ∪ 𝑌) ∪ 𝑍))    ⇒   ⊢ (𝜑 → 𝐹:𝐷–1-1-onto→𝑊)
Theorem	metakunt18 42223	Disjoint domains and codomains. (Contributed by metakunt, 28-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    ⇒   ⊢ (𝜑 → ((((1...(𝐼 − 1)) ∩ (𝐼...(𝑀 − 1))) = ∅ ∧ ((1...(𝐼 − 1)) ∩ {𝑀}) = ∅ ∧ ((𝐼...(𝑀 − 1)) ∩ {𝑀}) = ∅) ∧ (((((𝑀 − 𝐼) + 1)...(𝑀 − 1)) ∩ (1...(𝑀 − 𝐼))) = ∅ ∧ ((((𝑀 − 𝐼) + 1)...(𝑀 − 1)) ∩ {𝑀}) = ∅ ∧ ((1...(𝑀 − 𝐼)) ∩ {𝑀}) = ∅)))
Theorem	metakunt19 42224*	Domains on restrictions of functions. (Contributed by metakunt, 28-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐵 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝑀, 𝑀, if(𝑥 < 𝐼, (𝑥 + (𝑀 − 𝐼)), (𝑥 + (1 − 𝐼)))))    &   ⊢ 𝐶 = (𝑥 ∈ (1...(𝐼 − 1)) ↦ (𝑥 + (𝑀 − 𝐼)))    &   ⊢ 𝐷 = (𝑥 ∈ (𝐼...(𝑀 − 1)) ↦ (𝑥 + (1 − 𝐼)))    ⇒   ⊢ (𝜑 → ((𝐶 Fn (1...(𝐼 − 1)) ∧ 𝐷 Fn (𝐼...(𝑀 − 1)) ∧ (𝐶 ∪ 𝐷) Fn ((1...(𝐼 − 1)) ∪ (𝐼...(𝑀 − 1)))) ∧ {⟨𝑀, 𝑀⟩} Fn {𝑀}))
Theorem	metakunt20 42225*	Show that B coincides on the union of bijections of functions. (Contributed by metakunt, 28-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐵 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝑀, 𝑀, if(𝑥 < 𝐼, (𝑥 + (𝑀 − 𝐼)), (𝑥 + (1 − 𝐼)))))    &   ⊢ 𝐶 = (𝑥 ∈ (1...(𝐼 − 1)) ↦ (𝑥 + (𝑀 − 𝐼)))    &   ⊢ 𝐷 = (𝑥 ∈ (𝐼...(𝑀 − 1)) ↦ (𝑥 + (1 − 𝐼)))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    &   ⊢ (𝜑 → 𝑋 = 𝑀)    ⇒   ⊢ (𝜑 → (𝐵‘𝑋) = (((𝐶 ∪ 𝐷) ∪ {⟨𝑀, 𝑀⟩})‘𝑋))
Theorem	metakunt21 42226*	Show that B coincides on the union of bijections of functions. (Contributed by metakunt, 28-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐵 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝑀, 𝑀, if(𝑥 < 𝐼, (𝑥 + (𝑀 − 𝐼)), (𝑥 + (1 − 𝐼)))))    &   ⊢ 𝐶 = (𝑥 ∈ (1...(𝐼 − 1)) ↦ (𝑥 + (𝑀 − 𝐼)))    &   ⊢ 𝐷 = (𝑥 ∈ (𝐼...(𝑀 − 1)) ↦ (𝑥 + (1 − 𝐼)))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    &   ⊢ (𝜑 → ¬ 𝑋 = 𝑀)    &   ⊢ (𝜑 → 𝑋 < 𝐼)    ⇒   ⊢ (𝜑 → (𝐵‘𝑋) = (((𝐶 ∪ 𝐷) ∪ {⟨𝑀, 𝑀⟩})‘𝑋))
Theorem	metakunt22 42227*	Show that B coincides on the union of bijections of functions. (Contributed by metakunt, 28-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐵 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝑀, 𝑀, if(𝑥 < 𝐼, (𝑥 + (𝑀 − 𝐼)), (𝑥 + (1 − 𝐼)))))    &   ⊢ 𝐶 = (𝑥 ∈ (1...(𝐼 − 1)) ↦ (𝑥 + (𝑀 − 𝐼)))    &   ⊢ 𝐷 = (𝑥 ∈ (𝐼...(𝑀 − 1)) ↦ (𝑥 + (1 − 𝐼)))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    &   ⊢ (𝜑 → ¬ 𝑋 = 𝑀)    &   ⊢ (𝜑 → ¬ 𝑋 < 𝐼)    ⇒   ⊢ (𝜑 → (𝐵‘𝑋) = (((𝐶 ∪ 𝐷) ∪ {⟨𝑀, 𝑀⟩})‘𝑋))
Theorem	metakunt23 42228*	B coincides on the union of bijections of functions. (Contributed by metakunt, 28-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐵 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝑀, 𝑀, if(𝑥 < 𝐼, (𝑥 + (𝑀 − 𝐼)), (𝑥 + (1 − 𝐼)))))    &   ⊢ 𝐶 = (𝑥 ∈ (1...(𝐼 − 1)) ↦ (𝑥 + (𝑀 − 𝐼)))    &   ⊢ 𝐷 = (𝑥 ∈ (𝐼...(𝑀 − 1)) ↦ (𝑥 + (1 − 𝐼)))    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    ⇒   ⊢ (𝜑 → (𝐵‘𝑋) = (((𝐶 ∪ 𝐷) ∪ {⟨𝑀, 𝑀⟩})‘𝑋))
Theorem	metakunt24 42229	Technical condition such that metakunt17 42222 holds. (Contributed by metakunt, 28-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    ⇒   ⊢ (𝜑 → ((((1...(𝐼 − 1)) ∪ (𝐼...(𝑀 − 1))) ∩ {𝑀}) = ∅ ∧ (1...𝑀) = (((1...(𝐼 − 1)) ∪ (𝐼...(𝑀 − 1))) ∪ {𝑀}) ∧ (1...𝑀) = (((((𝑀 − 𝐼) + 1)...(𝑀 − 1)) ∪ (1...(𝑀 − 𝐼))) ∪ {𝑀})))
Theorem	metakunt25 42230*	B is a permutation. (Contributed by metakunt, 28-May-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐵 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝑀, 𝑀, if(𝑥 < 𝐼, (𝑥 + (𝑀 − 𝐼)), (𝑥 + (1 − 𝐼)))))    ⇒   ⊢ (𝜑 → 𝐵:(1...𝑀)–1-1-onto→(1...𝑀))
Theorem	metakunt26 42231*	Construction of one solution of the increment equation system. (Contributed by metakunt, 7-Jul-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ 𝐵 = (𝑧 ∈ (1...𝑀) ↦ if(𝑧 = 𝑀, 𝑀, if(𝑧 < 𝐼, (𝑧 + (𝑀 − 𝐼)), (𝑧 + (1 − 𝐼)))))    &   ⊢ (𝜑 → 𝑋 = 𝐼)    ⇒   ⊢ (𝜑 → (𝐶‘(𝐵‘(𝐴‘𝑋))) = 𝑋)
Theorem	metakunt27 42232*	Construction of one solution of the increment equation system. (Contributed by metakunt, 7-Jul-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐵 = (𝑧 ∈ (1...𝑀) ↦ if(𝑧 = 𝑀, 𝑀, if(𝑧 < 𝐼, (𝑧 + (𝑀 − 𝐼)), (𝑧 + (1 − 𝐼)))))    &   ⊢ (𝜑 → ¬ 𝑋 = 𝐼)    &   ⊢ (𝜑 → 𝑋 < 𝐼)    ⇒   ⊢ (𝜑 → (𝐵‘(𝐴‘𝑋)) = (𝑋 + (𝑀 − 𝐼)))
Theorem	metakunt28 42233*	Construction of one solution of the increment equation system. (Contributed by metakunt, 7-Jul-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐵 = (𝑧 ∈ (1...𝑀) ↦ if(𝑧 = 𝑀, 𝑀, if(𝑧 < 𝐼, (𝑧 + (𝑀 − 𝐼)), (𝑧 + (1 − 𝐼)))))    &   ⊢ (𝜑 → ¬ 𝑋 = 𝐼)    &   ⊢ (𝜑 → ¬ 𝑋 < 𝐼)    ⇒   ⊢ (𝜑 → (𝐵‘(𝐴‘𝑋)) = (𝑋 − 𝐼))
Theorem	metakunt29 42234*	Construction of one solution of the increment equation system. (Contributed by metakunt, 7-Jul-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐵 = (𝑧 ∈ (1...𝑀) ↦ if(𝑧 = 𝑀, 𝑀, if(𝑧 < 𝐼, (𝑧 + (𝑀 − 𝐼)), (𝑧 + (1 − 𝐼)))))    &   ⊢ (𝜑 → ¬ 𝑋 = 𝐼)    &   ⊢ (𝜑 → 𝑋 < 𝐼)    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ 𝐻 = if(𝐼 ≤ (𝑋 + (𝑀 − 𝐼)), 1, 0)    ⇒   ⊢ (𝜑 → (𝐶‘(𝐵‘(𝐴‘𝑋))) = ((𝑋 + (𝑀 − 𝐼)) + 𝐻))
Theorem	metakunt30 42235*	Construction of one solution of the increment equation system. (Contributed by metakunt, 7-Jul-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐵 = (𝑧 ∈ (1...𝑀) ↦ if(𝑧 = 𝑀, 𝑀, if(𝑧 < 𝐼, (𝑧 + (𝑀 − 𝐼)), (𝑧 + (1 − 𝐼)))))    &   ⊢ (𝜑 → ¬ 𝑋 = 𝐼)    &   ⊢ (𝜑 → ¬ 𝑋 < 𝐼)    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ 𝐻 = if(𝐼 ≤ (𝑋 − 𝐼), 1, 0)    ⇒   ⊢ (𝜑 → (𝐶‘(𝐵‘(𝐴‘𝑋))) = ((𝑋 − 𝐼) + 𝐻))
Theorem	metakunt31 42236*	Construction of one solution of the increment equation system. (Contributed by metakunt, 18-Jul-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐵 = (𝑧 ∈ (1...𝑀) ↦ if(𝑧 = 𝑀, 𝑀, if(𝑧 < 𝐼, (𝑧 + (𝑀 − 𝐼)), (𝑧 + (1 − 𝐼)))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ 𝐺 = if(𝐼 ≤ (𝑋 + (𝑀 − 𝐼)), 1, 0)    &   ⊢ 𝐻 = if(𝐼 ≤ (𝑋 − 𝐼), 1, 0)    &   ⊢ 𝑅 = if(𝑋 = 𝐼, 𝑋, if(𝑋 < 𝐼, ((𝑋 + (𝑀 − 𝐼)) + 𝐺), ((𝑋 − 𝐼) + 𝐻)))    ⇒   ⊢ (𝜑 → (𝐶‘(𝐵‘(𝐴‘𝑋))) = 𝑅)
Theorem	metakunt32 42237*	Construction of one solution of the increment equation system. (Contributed by metakunt, 18-Jul-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ (𝜑 → 𝑋 ∈ (1...𝑀))    &   ⊢ 𝐷 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑥, if(𝑥 < 𝐼, ((𝑥 + (𝑀 − 𝐼)) + if(𝐼 ≤ (𝑥 + (𝑀 − 𝐼)), 1, 0)), ((𝑥 − 𝐼) + if(𝐼 ≤ (𝑥 − 𝐼), 1, 0)))))    &   ⊢ 𝐺 = if(𝐼 ≤ (𝑋 + (𝑀 − 𝐼)), 1, 0)    &   ⊢ 𝐻 = if(𝐼 ≤ (𝑋 − 𝐼), 1, 0)    &   ⊢ 𝑅 = if(𝑋 = 𝐼, 𝑋, if(𝑋 < 𝐼, ((𝑋 + (𝑀 − 𝐼)) + 𝐺), ((𝑋 − 𝐼) + 𝐻)))    ⇒   ⊢ (𝜑 → (𝐷‘𝑋) = 𝑅)
Theorem	metakunt33 42238*	Construction of one solution of the increment equation system. (Contributed by metakunt, 18-Jul-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐴 = (𝑥 ∈ (1...𝑀) ↦ if(𝑥 = 𝐼, 𝑀, if(𝑥 < 𝐼, 𝑥, (𝑥 − 1))))    &   ⊢ 𝐵 = (𝑧 ∈ (1...𝑀) ↦ if(𝑧 = 𝑀, 𝑀, if(𝑧 < 𝐼, (𝑧 + (𝑀 − 𝐼)), (𝑧 + (1 − 𝐼)))))    &   ⊢ 𝐶 = (𝑦 ∈ (1...𝑀) ↦ if(𝑦 = 𝑀, 𝐼, if(𝑦 < 𝐼, 𝑦, (𝑦 + 1))))    &   ⊢ 𝐷 = (𝑤 ∈ (1...𝑀) ↦ if(𝑤 = 𝐼, 𝑤, if(𝑤 < 𝐼, ((𝑤 + (𝑀 − 𝐼)) + if(𝐼 ≤ (𝑤 + (𝑀 − 𝐼)), 1, 0)), ((𝑤 − 𝐼) + if(𝐼 ≤ (𝑤 − 𝐼), 1, 0)))))    ⇒   ⊢ (𝜑 → (𝐶 ∘ (𝐵 ∘ 𝐴)) = 𝐷)
Theorem	metakunt34 42239*	𝐷 is a permutation. (Contributed by metakunt, 18-Jul-2024.)
⊢ (𝜑 → 𝑀 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ∈ ℕ)    &   ⊢ (𝜑 → 𝐼 ≤ 𝑀)    &   ⊢ 𝐷 = (𝑤 ∈ (1...𝑀) ↦ if(𝑤 = 𝐼, 𝑤, if(𝑤 < 𝐼, ((𝑤 + (𝑀 − 𝐼)) + if(𝐼 ≤ (𝑤 + (𝑀 − 𝐼)), 1, 0)), ((𝑤 − 𝐼) + if(𝐼 ≤ (𝑤 − 𝐼), 1, 0)))))    ⇒   ⊢ (𝜑 → 𝐷:(1...𝑀)–1-1-onto→(1...𝑀))
21.29.10  Unused lemmas scheduled for deletion
Theorem	fac2xp3 42240	Factorial of 2x+3, sublemma for sublemma for AKS. (Contributed by metakunt, 19-Apr-2024.)
⊢ (𝑥 ∈ ℕ0 → (!‘((2 · 𝑥) + 3)) = ((!‘((2 · 𝑥) + 1)) · (((2 · 𝑥) + 2) · ((2 · 𝑥) + 3))))
Theorem	prodsplit 42241*	Product split into two factors, original by Steven Nguyen. (Contributed by metakunt, 21-Apr-2024.)
⊢ (𝜑 → 𝑀 ∈ ℤ)    &   ⊢ (𝜑 → 𝑁 ∈ ℤ)    &   ⊢ (𝜑 → 𝑀 ≤ 𝑁)    &   ⊢ (𝜑 → 𝐾 ∈ ℕ0)    &   ⊢ ((𝜑 ∧ 𝑘 ∈ (𝑀...(𝑁 + 𝐾))) → 𝐴 ∈ ℂ)    ⇒   ⊢ (𝜑 → ∏𝑘 ∈ (𝑀...(𝑁 + 𝐾))𝐴 = (∏𝑘 ∈ (𝑀...𝑁)𝐴 · ∏𝑘 ∈ ((𝑁 + 1)...(𝑁 + 𝐾))𝐴))
Theorem	2xp3dxp2ge1d 42242	2x+3 is greater than or equal to x+2 for x >= -1, a deduction version (Contributed by metakunt, 21-Apr-2024.)
⊢ (𝜑 → 𝑋 ∈ (-1[,)+∞))    ⇒   ⊢ (𝜑 → 1 ≤ (((2 · 𝑋) + 3) / (𝑋 + 2)))
Theorem	factwoffsmonot 42243	A factorial with offset is monotonely increasing. (Contributed by metakunt, 20-Apr-2024.)
⊢ (((𝑋 ∈ ℕ0 ∧ 𝑌 ∈ ℕ0 ∧ 𝑋 ≤ 𝑌) ∧ 𝑁 ∈ ℕ0) → (!‘(𝑋 + 𝑁)) ≤ (!‘(𝑌 + 𝑁)))
21.30  Mathbox for Steven Nguyen
21.30.1  Utility theorems
Theorem	jarrii 42244	Inference associated with jarri 107. A consequence of ax-mp 5 and ax-1 6. (Contributed by SN, 14-Oct-2025.)
⊢ 𝜓    &   ⊢ ((𝜑 → 𝜓) → 𝜒)    ⇒   ⊢ 𝜒
Theorem	intnanrt 42245	Introduction of conjunct inside of a contradiction. Would be used in elfvov1 7473. (Contributed by SN, 18-May-2025.)
⊢ (¬ 𝜑 → ¬ (𝜑 ∧ 𝜓))
Theorem	ioin9i8 42246	Miscellaneous inference creating a biconditional from an implied converse implication. (Contributed by Steven Nguyen, 17-Jul-2022.)
⊢ (𝜑 → (𝜓 ∨ 𝜒))    &   ⊢ (𝜒 → ¬ 𝜃)    &   ⊢ (𝜓 → 𝜃)    ⇒   ⊢ (𝜑 → (𝜓 ↔ 𝜃))
Theorem	jaodd 42247	Double deduction form of jaoi 858. (Contributed by Steven Nguyen, 17-Jul-2022.)
⊢ (𝜑 → (𝜓 → (𝜒 → 𝜃)))    &   ⊢ (𝜑 → (𝜓 → (𝜏 → 𝜃)))    ⇒   ⊢ (𝜑 → (𝜓 → ((𝜒 ∨ 𝜏) → 𝜃)))
Theorem	syl3an12 42248	A double syllogism inference. (Contributed by SN, 15-Sep-2024.)
⊢ (𝜑 → 𝜓)    &   ⊢ (𝜒 → 𝜃)    &   ⊢ ((𝜓 ∧ 𝜃 ∧ 𝜏) → 𝜂)    ⇒   ⊢ ((𝜑 ∧ 𝜒 ∧ 𝜏) → 𝜂)
Theorem	exbiii 42249	Inference associated with exbii 1848. Weaker version of eximii 1837. (Contributed by SN, 14-Oct-2025.)
⊢ ∃𝑥𝜑    &   ⊢ (𝜑 ↔ 𝜓)    ⇒   ⊢ ∃𝑥𝜓
Theorem	sbtd 42250*	A true statement is true upon substitution (deduction). A similar proof is possible for icht 47439. (Contributed by SN, 4-May-2024.)
⊢ (𝜑 → 𝜓)    ⇒   ⊢ (𝜑 → [𝑡 / 𝑥]𝜓)
Theorem	sbor2 42251	One direction of sbor 2307, using fewer axioms. Compare 19.33 1884. (Contributed by Steven Nguyen, 18-Aug-2023.)
⊢ (([𝑡 / 𝑥]𝜑 ∨ [𝑡 / 𝑥]𝜓) → [𝑡 / 𝑥](𝜑 ∨ 𝜓))
Theorem	sbalexi 42252*	Inference form of sbalex 2242, avoiding ax-10 2141 by using ax-gen 1795. (Contributed by SN, 12-Aug-2025.)
⊢ ∃𝑥(𝑥 = 𝑦 ∧ 𝜑)    ⇒   ⊢ ∀𝑥(𝑥 = 𝑦 → 𝜑)
Theorem	19.9dev 42253*	19.9d 2203 in the case of an existential quantifier, avoiding the ax-10 2141 from nfex 2324 that would be used for the hypothesis of 19.9d 2203, at the cost of an additional DV condition on 𝑦, 𝜑. (Contributed by SN, 26-May-2024.)
⊢ (𝜑 → Ⅎ𝑥𝜓)    ⇒   ⊢ (𝜑 → (∃𝑥∃𝑦𝜓 ↔ ∃𝑦𝜓))
Theorem	3rspcedvd 42254*	Triple application of rspcedvd 3624. (Contributed by Steven Nguyen, 27-Feb-2023.)
⊢ (𝜑 → 𝐴 ∈ 𝐷)    &   ⊢ (𝜑 → 𝐵 ∈ 𝐷)    &   ⊢ (𝜑 → 𝐶 ∈ 𝐷)    &   ⊢ ((𝜑 ∧ 𝑥 = 𝐴) → (𝜓 ↔ 𝜒))    &   ⊢ ((𝜑 ∧ 𝑦 = 𝐵) → (𝜒 ↔ 𝜃))    &   ⊢ ((𝜑 ∧ 𝑧 = 𝐶) → (𝜃 ↔ 𝜏))    &   ⊢ (𝜑 → 𝜏)    ⇒   ⊢ (𝜑 → ∃𝑥 ∈ 𝐷 ∃𝑦 ∈ 𝐷 ∃𝑧 ∈ 𝐷 𝜓)
Theorem	sn-axrep5v 42255*	A condensed form of axrep5 5287. (Contributed by SN, 21-Sep-2023.)
⊢ (∀𝑤 ∈ 𝑥 ∃*𝑧𝜑 → ∃𝑦∀𝑧(𝑧 ∈ 𝑦 ↔ ∃𝑤 ∈ 𝑥 𝜑))
Theorem	sn-axprlem3 42256*	axprlem3 5425 using only Tarski's FOL axiom schemes and ax-rep 5279. (Contributed by SN, 22-Sep-2023.)
⊢ ∃𝑦∀𝑧(𝑧 ∈ 𝑦 ↔ ∃𝑤 ∈ 𝑥 if-(𝜑, 𝑧 = 𝑎, 𝑧 = 𝑏))
Theorem	sn-exelALT 42257*	Alternate proof of exel 5438, avoiding ax-pr 5432 but requiring ax-5 1910, ax-9 2118, and ax-pow 5365. This is similar to how elALT2 5369 uses ax-pow 5365 instead of ax-pr 5432 compared to el 5442. (Contributed by SN, 18-Sep-2023.) (Proof modification is discouraged.) (New usage is discouraged.)
⊢ ∃𝑦∃𝑥 𝑥 ∈ 𝑦
Theorem	ss2ab1 42258	Class abstractions in a subclass relationship, closed form. One direction of ss2ab 4062 using fewer axioms. (Contributed by SN, 22-Dec-2024.)
⊢ (∀𝑥(𝜑 → 𝜓) → {𝑥 ∣ 𝜑} ⊆ {𝑥 ∣ 𝜓})
Theorem	ssabdv 42259*	Deduction of abstraction subclass from implication. (Contributed by SN, 22-Dec-2024.)
⊢ (𝜑 → (𝑥 ∈ 𝐴 → 𝜓))    ⇒   ⊢ (𝜑 → 𝐴 ⊆ {𝑥 ∣ 𝜓})
Theorem	sn-iotalem 42260*	An unused lemma showing that many equivalences involving df-iota 6514 are potentially provable without ax-10 2141, ax-11 2157, ax-12 2177. (Contributed by SN, 6-Nov-2024.)
⊢ {𝑦 ∣ {𝑥 ∣ 𝜑} = {𝑦}} = {𝑧 ∣ {𝑦 ∣ {𝑥 ∣ 𝜑} = {𝑦}} = {𝑧}}
Theorem	sn-iotalemcor 42261*	Corollary of sn-iotalem 42260. Compare sb8iota 6525. (Contributed by SN, 6-Nov-2024.)
⊢ (℩𝑥𝜑) = (℩𝑦{𝑥 ∣ 𝜑} = {𝑦})
Theorem	abbi1sn 42262*	Originally part of uniabio 6528. Convert a theorem about df-iota 6514 to one about dfiota2 6515, without ax-10 2141, ax-11 2157, ax-12 2177. Although, eu6 2574 uses ax-10 2141 and ax-12 2177. (Contributed by SN, 23-Nov-2024.)
⊢ (∀𝑥(𝜑 ↔ 𝑥 = 𝑦) → {𝑥 ∣ 𝜑} = {𝑦})
Theorem	brif2 42263	Move a relation inside and outside the conditional operator. (Contributed by SN, 14-Aug-2024.)
⊢ (𝐶𝑅if(𝜑, 𝐴, 𝐵) ↔ if-(𝜑, 𝐶𝑅𝐴, 𝐶𝑅𝐵))
Theorem	brif12 42264	Move a relation inside and outside the conditional operator. (Contributed by SN, 14-Aug-2024.)
⊢ (if(𝜑, 𝐴, 𝐵)𝑅if(𝜑, 𝐶, 𝐷) ↔ if-(𝜑, 𝐴𝑅𝐶, 𝐵𝑅𝐷))
Theorem	pssexg 42265	The proper subset of a set is also a set. (Contributed by Steven Nguyen, 17-Jul-2022.)
⊢ ((𝐴 ⊊ 𝐵 ∧ 𝐵 ∈ 𝐶) → 𝐴 ∈ V)
Theorem	pssn0 42266	A proper superset is nonempty. (Contributed by Steven Nguyen, 17-Jul-2022.)
⊢ (𝐴 ⊊ 𝐵 → 𝐵 ≠ ∅)
Theorem	psspwb 42267	Classes are proper subclasses if and only if their power classes are proper subclasses. (Contributed by Steven Nguyen, 17-Jul-2022.)
⊢ (𝐴 ⊊ 𝐵 ↔ 𝒫 𝐴 ⊊ 𝒫 𝐵)
Theorem	xppss12 42268	Proper subset theorem for Cartesian product. (Contributed by Steven Nguyen, 17-Jul-2022.)
⊢ ((𝐴 ⊊ 𝐵 ∧ 𝐶 ⊊ 𝐷) → (𝐴 × 𝐶) ⊊ (𝐵 × 𝐷))
Theorem	elpwbi 42269	Membership in a power set, biconditional. (Contributed by Steven Nguyen, 17-Jul-2022.) (Proof shortened by Steven Nguyen, 16-Sep-2022.)
⊢ 𝐵 ∈ V    ⇒   ⊢ (𝐴 ⊆ 𝐵 ↔ 𝐴 ∈ 𝒫 𝐵)
Theorem	imaopab 42270*	The image of a class of ordered pairs. (Contributed by Steven Nguyen, 6-Jun-2023.)
⊢ ({⟨𝑥, 𝑦⟩ ∣ 𝜑} “ 𝐴) = {𝑦 ∣ ∃𝑥 ∈ 𝐴 𝜑}
Theorem	fnsnbt 42271	A function's domain is a singleton iff the function is a singleton. (Contributed by Steven Nguyen, 18-Aug-2023.)
⊢ (𝐴 ∈ V → (𝐹 Fn {𝐴} ↔ 𝐹 = {⟨𝐴, (𝐹‘𝐴)⟩}))
Theorem	fnimasnd 42272	The image of a function by a singleton whose element is in the domain of the function. (Contributed by Steven Nguyen, 7-Jun-2023.)
⊢ (𝜑 → 𝐹 Fn 𝐴)    &   ⊢ (𝜑 → 𝑆 ∈ 𝐴)    ⇒   ⊢ (𝜑 → (𝐹 “ {𝑆}) = {(𝐹‘𝑆)})
Theorem	eqresfnbd 42273	Property of being the restriction of a function. Note that this is closer to funssres 6610 than fnssres 6691. (Contributed by SN, 11-Mar-2025.)
⊢ (𝜑 → 𝐹 Fn 𝐵)    &   ⊢ (𝜑 → 𝐴 ⊆ 𝐵)    ⇒   ⊢ (𝜑 → (𝑅 = (𝐹 ↾ 𝐴) ↔ (𝑅 Fn 𝐴 ∧ 𝑅 ⊆ 𝐹)))
Theorem	f1o2d2 42274*	Sufficient condition for a binary function expressed in maps-to notation to be bijective. (Contributed by SN, 11-Mar-2025.)
⊢ 𝐹 = (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐶)    &   ⊢ ((𝜑 ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)) → 𝐶 ∈ 𝐷)    &   ⊢ ((𝜑 ∧ 𝑧 ∈ 𝐷) → 𝐼 ∈ 𝐴)    &   ⊢ ((𝜑 ∧ 𝑧 ∈ 𝐷) → 𝐽 ∈ 𝐵)    &   ⊢ ((𝜑 ∧ ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑧 ∈ 𝐷)) → ((𝑥 = 𝐼 ∧ 𝑦 = 𝐽) ↔ 𝑧 = 𝐶))    ⇒   ⊢ (𝜑 → 𝐹:(𝐴 × 𝐵)–1-1-onto→𝐷)
Theorem	fmpocos 42275*	Composition of two functions. Variation of fmpoco 8120 with more context in the substitution hypothesis for 𝑇. (Contributed by SN, 14-Mar-2025.)
⊢ ((𝜑 ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)) → 𝑅 ∈ 𝐶)    &   ⊢ (𝜑 → 𝐹 = (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑅))    &   ⊢ (𝜑 → 𝐺 = (𝑧 ∈ 𝐶 ↦ 𝑆))    &   ⊢ ((𝜑 ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)) → ⦋𝑅 / 𝑧⦌𝑆 = 𝑇)    ⇒   ⊢ (𝜑 → (𝐺 ∘ 𝐹) = (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝑇))
Theorem	ovmpogad 42276*	Value of an operation given by a maps-to rule. Deduction form of ovmpoga 7587. (Contributed by SN, 14-Mar-2025.)
⊢ 𝐹 = (𝑥 ∈ 𝐶, 𝑦 ∈ 𝐷 ↦ 𝑅)    &   ⊢ ((𝑥 = 𝐴 ∧ 𝑦 = 𝐵) → 𝑅 = 𝑆)    &   ⊢ (𝜑 → 𝐴 ∈ 𝐶)    &   ⊢ (𝜑 → 𝐵 ∈ 𝐷)    &   ⊢ (𝜑 → 𝑆 ∈ 𝑉)    ⇒   ⊢ (𝜑 → (𝐴𝐹𝐵) = 𝑆)
Theorem	ofun 42277	A function operation of unions of disjoint functions is a union of function operations. (Contributed by SN, 16-Jun-2024.)
⊢ (𝜑 → 𝐴 Fn 𝑀)    &   ⊢ (𝜑 → 𝐵 Fn 𝑀)    &   ⊢ (𝜑 → 𝐶 Fn 𝑁)    &   ⊢ (𝜑 → 𝐷 Fn 𝑁)    &   ⊢ (𝜑 → 𝑀 ∈ 𝑉)    &   ⊢ (𝜑 → 𝑁 ∈ 𝑊)    &   ⊢ (𝜑 → (𝑀 ∩ 𝑁) = ∅)    ⇒   ⊢ (𝜑 → ((𝐴 ∪ 𝐶) ∘f 𝑅(𝐵 ∪ 𝐷)) = ((𝐴 ∘f 𝑅𝐵) ∪ (𝐶 ∘f 𝑅𝐷)))
Theorem	dfqs2 42278*	Alternate definition of quotient set. (Contributed by Steven Nguyen, 7-Jun-2023.)
⊢ (𝐴 / 𝑅) = ran (𝑥 ∈ 𝐴 ↦ [𝑥]𝑅)
Theorem	dfqs3 42279*	Alternate definition of quotient set. (Contributed by Steven Nguyen, 7-Jun-2023.)
⊢ (𝐴 / 𝑅) = ∪ 𝑥 ∈ 𝐴 {[𝑥]𝑅}
Theorem	qseq12d 42280	Equality theorem for quotient set, deduction form. (Contributed by Steven Nguyen, 30-Apr-2023.)
⊢ (𝜑 → 𝐴 = 𝐵)    &   ⊢ (𝜑 → 𝐶 = 𝐷)    ⇒   ⊢ (𝜑 → (𝐴 / 𝐶) = (𝐵 / 𝐷))
Theorem	qsalrel 42281*	The quotient set is equal to the singleton of 𝐴 when all elements are related and 𝐴 is nonempty. (Contributed by SN, 8-Jun-2023.)
⊢ ((𝜑 ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴)) → 𝑥 ∼ 𝑦)    &   ⊢ (𝜑 → ∼ Er 𝐴)    &   ⊢ (𝜑 → 𝑁 ∈ 𝐴)    ⇒   ⊢ (𝜑 → (𝐴 / ∼ ) = {𝐴})
Theorem	elmapssresd 42282	A restricted mapping is a mapping. EDITORIAL: Could be used to shorten elpm2r 8885 with some reordering involving mapsspm 8916. (Contributed by SN, 11-Mar-2025.)
⊢ (𝜑 → 𝐴 ∈ (𝐵 ↑m 𝐶))    &   ⊢ (𝜑 → 𝐷 ⊆ 𝐶)    ⇒   ⊢ (𝜑 → (𝐴 ↾ 𝐷) ∈ (𝐵 ↑m 𝐷))
Theorem	supinf 42283*	The supremum is the infimum of the upper bounds. (Contributed by SN, 29-Jun-2025.)
⊢ (𝜑 → < Or 𝐴)    &   ⊢ (𝜑 → ∃𝑥 ∈ 𝐴 (∀𝑦 ∈ 𝐵 ¬ 𝑥 < 𝑦 ∧ ∀𝑦 ∈ 𝐴 (𝑦 < 𝑥 → ∃𝑧 ∈ 𝐵 𝑦 < 𝑧)))    ⇒   ⊢ (𝜑 → sup(𝐵, 𝐴, < ) = inf({𝑥 ∈ 𝐴 ∣ ∀𝑤 ∈ 𝐵 ¬ 𝑥 < 𝑤}, 𝐴, < ))
Theorem	mapcod 42284	Compose two mappings. (Contributed by SN, 11-Mar-2025.)
⊢ (𝜑 → 𝐹 ∈ (𝐴 ↑m 𝐵))    &   ⊢ (𝜑 → 𝐺 ∈ (𝐵 ↑m 𝐶))    ⇒   ⊢ (𝜑 → (𝐹 ∘ 𝐺) ∈ (𝐴 ↑m 𝐶))
Theorem	fisdomnn 42285	A finite set is dominated by the set of natural numbers. (Contributed by SN, 6-Jul-2025.)
⊢ (𝐴 ∈ Fin → 𝐴 ≺ ℕ)
Theorem	ltex 42286	The less-than relation is a set. (Contributed by SN, 5-Jun-2025.)
⊢ < ∈ V
Theorem	leex 42287	The less-than-or-equal-to relation is a set. (Contributed by SN, 5-Jun-2025.)
⊢ ≤ ∈ V
Theorem	subex 42288	The subtraction operation is a set. (Contributed by SN, 5-Jun-2025.)
⊢ − ∈ V
Theorem	absex 42289	The absolute value function is a set. (Contributed by SN, 5-Jun-2025.)
⊢ abs ∈ V
Theorem	cjex 42290	The conjugate function is a set. (Contributed by SN, 5-Jun-2025.)
⊢ ∗ ∈ V
Theorem	fzosumm1 42291*	Separate out the last term in a finite sum. (Contributed by Steven Nguyen, 22-Aug-2023.)
⊢ (𝜑 → (𝑁 − 1) ∈ (ℤ≥‘𝑀))    &   ⊢ ((𝜑 ∧ 𝑘 ∈ (𝑀..^𝑁)) → 𝐴 ∈ ℂ)    &   ⊢ (𝑘 = (𝑁 − 1) → 𝐴 = 𝐵)    &   ⊢ (𝜑 → 𝑁 ∈ ℤ)    ⇒   ⊢ (𝜑 → Σ𝑘 ∈ (𝑀..^𝑁)𝐴 = (Σ𝑘 ∈ (𝑀..^(𝑁 − 1))𝐴 + 𝐵))
Theorem	ccatcan2d 42292	Cancellation law for concatenation. (Contributed by SN, 6-Sep-2023.)
⊢ (𝜑 → 𝐴 ∈ Word 𝑉)    &   ⊢ (𝜑 → 𝐵 ∈ Word 𝑉)    &   ⊢ (𝜑 → 𝐶 ∈ Word 𝑉)    ⇒   ⊢ (𝜑 → ((𝐴 ++ 𝐶) = (𝐵 ++ 𝐶) ↔ 𝐴 = 𝐵))
21.30.2  Arithmetic theorems Towards the start of this section are several proofs regarding the different complex number axioms that could be used to prove some results. For example, ax-1rid 11225 is used in mulrid 11259 related theorems, so one could trade off the extra axioms in mulrid 11259 for the axioms needed to prove that something is a real number. Another example is avoiding complex number closure laws by using real number closure laws and then using ax-resscn 11212; in the other direction, real number closure laws can be avoided by using ax-resscn 11212 and then the complex number closure laws. (This only works if the result of (𝐴 + 𝐵) only needs to be a complex number). The natural numbers are especially amenable to axiom reductions, as the set ℕ is the recursive set {1, (1 + 1), ((1 + 1) + 1)}, etc., i.e. the set of numbers formed by only additions of 1. The digits 2 through 9 are defined so that they expand into additions of 1. This conveniently allows for adding natural numbers by rearranging parentheses, as shown below: (4 + 3) = 7 ((3 + 1) + (2 + 1)) = (6 + 1) ((((1 + 1) + 1) + 1) + ((1 + 1) + 1)) = ((((((1 + 1) + 1) + 1) + 1) + 1) + 1) This only requires ax-addass 11220, ax-1cn 11213, and ax-addcl 11215. (And in practice, the expression isn't fully expanded into ones.) Multiplication by 1 requires either mullidi 11266 or (ax-1rid 11225 and 1re 11261) as seen in 1t1e1 12428 and 1t1e1ALT 42296. Multiplying with greater natural numbers uses ax-distr 11222. Still, this takes fewer axioms than adding zero, which is often implicit in theorems such as (9 + 1) = ;10. Adding zero uses almost every complex number axiom, though notably not ax-mulcom 11219 (see readdrid 42439 and readdlid 42433).
Theorem	c0exALT 42293	Alternate proof of c0ex 11255 using more set theory axioms but fewer complex number axioms (add ax-10 2141, ax-11 2157, ax-13 2377, ax-nul 5306, and remove ax-1cn 11213, ax-icn 11214, ax-addcl 11215, and ax-mulcl 11217). (Contributed by Steven Nguyen, 4-Dec-2022.) (Proof modification is discouraged.) (New usage is discouraged.)
⊢ 0 ∈ V
Theorem	0cnALT3 42294	Alternate proof of 0cn 11253 using ax-resscn 11212, ax-addrcl 11216, ax-rnegex 11226, ax-cnre 11228 instead of ax-icn 11214, ax-addcl 11215, ax-mulcl 11217, ax-i2m1 11223. Version of 0cnALT 11496 using ax-1cn 11213 instead of ax-icn 11214. (Contributed by Steven Nguyen, 7-Jan-2022.) (Proof modification is discouraged.) (New usage is discouraged.)
⊢ 0 ∈ ℂ
Theorem	elre0re 42295	Specialized version of 0red 11264 without using ax-1cn 11213 and ax-cnre 11228. (Contributed by Steven Nguyen, 28-Jan-2023.)
⊢ (𝐴 ∈ ℝ → 0 ∈ ℝ)
Theorem	1t1e1ALT 42296	Alternate proof of 1t1e1 12428 using a different set of axioms (add ax-mulrcl 11218, ax-i2m1 11223, ax-1ne0 11224, ax-rrecex 11227 and remove ax-resscn 11212, ax-mulcom 11219, ax-mulass 11221, ax-distr 11222). (Contributed by Steven Nguyen, 20-Sep-2022.) (Proof modification is discouraged.) (New usage is discouraged.)
⊢ (1 · 1) = 1
Theorem	lttrii 42297	'Less than' is transitive. (Contributed by SN, 26-Aug-2025.)
⊢ 𝐴 ∈ ℝ    &   ⊢ 𝐵 ∈ ℝ    &   ⊢ 𝐶 ∈ ℝ    &   ⊢ 𝐴 < 𝐵    &   ⊢ 𝐵 < 𝐶    ⇒   ⊢ 𝐴 < 𝐶
Theorem	remulcan2d 42298	mulcan2d 11897 for real numbers using fewer axioms. (Contributed by Steven Nguyen, 15-Apr-2023.)
⊢ (𝜑 → 𝐴 ∈ ℝ)    &   ⊢ (𝜑 → 𝐵 ∈ ℝ)    &   ⊢ (𝜑 → 𝐶 ∈ ℝ)    &   ⊢ (𝜑 → 𝐶 ≠ 0)    ⇒   ⊢ (𝜑 → ((𝐴 · 𝐶) = (𝐵 · 𝐶) ↔ 𝐴 = 𝐵))
Theorem	readdridaddlidd 42299	Given some real number 𝐵 where 𝐴 acts like a right additive identity, derive that 𝐴 is a left additive identity. Note that the hypothesis is weaker than proving that 𝐴 is a right additive identity (for all numbers). Although, if there is a right additive identity, then by readdcan 11435, 𝐴 is the right additive identity. (Contributed by Steven Nguyen, 14-Jan-2023.)
⊢ (𝜑 → 𝐴 ∈ ℝ)    &   ⊢ (𝜑 → 𝐵 ∈ ℝ)    &   ⊢ (𝜑 → (𝐵 + 𝐴) = 𝐵)    ⇒   ⊢ ((𝜑 ∧ 𝐶 ∈ ℝ) → (𝐴 + 𝐶) = 𝐶)
Theorem	sn-1ne2 42300	A proof of 1ne2 12474 without using ax-mulcom 11219, ax-mulass 11221, ax-pre-mulgt0 11232. Based on mul02lem2 11438. (Contributed by SN, 13-Dec-2023.)
⊢ 1 ≠ 2