P. 403 of Theorem List - Metamath Proof Explorer

Theorem List for Metamath Proof Explorer - 40201-40300   *Has distinct variable group(s)

Type	Label	Description
Statement
Theorem	sgoldbaltlem1 40201	Lemma 1 for sgoldbalt 40203: If an even number greater than 4 is the sum of two primes, one of the prime summands must be odd, i.e. not 2. (Contributed by AV, 22-Jul-2020.)
⊢ ((𝑃 ∈ ℙ ∧ 𝑄 ∈ ℙ) → ((𝑁 ∈ Even ∧ 4 < 𝑁 ∧ 𝑁 = (𝑃 + 𝑄)) → 𝑄 ∈ Odd ))
Theorem	sgoldbaltlem2 40202	Lemma 2 for sgoldbalt 40203: If an even number greater than 4 is the sum of two primes, the primes must be odd, i.e. not 2. (Contributed by AV, 22-Jul-2020.)
⊢ ((𝑃 ∈ ℙ ∧ 𝑄 ∈ ℙ) → ((𝑁 ∈ Even ∧ 4 < 𝑁 ∧ 𝑁 = (𝑃 + 𝑄)) → (𝑃 ∈ Odd ∧ 𝑄 ∈ Odd )))
Theorem	sgoldbalt 40203*	An alternate (the original) formulation of the binary Goldbach conjecture: Every even integer greater than 2 can be expressed as the sum of two primes. (Contributed by AV, 22-Jul-2020.)
⊢ (∀𝑛 ∈ Even (4 < 𝑛 → 𝑛 ∈ GoldbachEven ) ↔ ∀𝑛 ∈ Even (2 < 𝑛 → ∃𝑝 ∈ ℙ ∃𝑞 ∈ ℙ 𝑛 = (𝑝 + 𝑞)))
Theorem	nnsum3primes4 40204*	4 is the sum of at most 3 (actually 2) primes. (Contributed by AV, 2-Aug-2020.)
⊢ ∃𝑑 ∈ ℕ ∃𝑓 ∈ (ℙ ↑𝑚 (1...𝑑))(𝑑 ≤ 3 ∧ 4 = Σ𝑘 ∈ (1...𝑑)(𝑓‘𝑘))
Theorem	nnsum4primes4 40205*	4 is the sum of at most 4 (actually 2) primes. (Contributed by AV, 23-Jul-2020.) (Proof shortened by AV, 2-Aug-2020.)
⊢ ∃𝑑 ∈ ℕ ∃𝑓 ∈ (ℙ ↑𝑚 (1...𝑑))(𝑑 ≤ 4 ∧ 4 = Σ𝑘 ∈ (1...𝑑)(𝑓‘𝑘))
Theorem	nnsum3primesprm 40206*	Every prime is "the sum of at most 3" (actually one - the prime itself) primes. (Contributed by AV, 2-Aug-2020.) (Proof shortened by AV, 17-Apr-2021.)
⊢ (𝑃 ∈ ℙ → ∃𝑑 ∈ ℕ ∃𝑓 ∈ (ℙ ↑𝑚 (1...𝑑))(𝑑 ≤ 3 ∧ 𝑃 = Σ𝑘 ∈ (1...𝑑)(𝑓‘𝑘)))
Theorem	nnsum4primesprm 40207*	Every prime is "the sum of at most 4" (actually one - the prime itself) primes. (Contributed by AV, 23-Jul-2020.) (Proof shortened by AV, 2-Aug-2020.)
⊢ (𝑃 ∈ ℙ → ∃𝑑 ∈ ℕ ∃𝑓 ∈ (ℙ ↑𝑚 (1...𝑑))(𝑑 ≤ 4 ∧ 𝑃 = Σ𝑘 ∈ (1...𝑑)(𝑓‘𝑘)))
Theorem	nnsum3primesgbe 40208*	Any even Goldbach number is the sum of at most 3 (actually 2) primes. (Contributed by AV, 2-Aug-2020.)
⊢ (𝑁 ∈ GoldbachEven → ∃𝑑 ∈ ℕ ∃𝑓 ∈ (ℙ ↑𝑚 (1...𝑑))(𝑑 ≤ 3 ∧ 𝑁 = Σ𝑘 ∈ (1...𝑑)(𝑓‘𝑘)))
Theorem	nnsum4primesgbe 40209*	Any even Goldbach number is the sum of at most 4 (actually 2) primes. (Contributed by AV, 23-Jul-2020.) (Proof shortened by AV, 2-Aug-2020.)
⊢ (𝑁 ∈ GoldbachEven → ∃𝑑 ∈ ℕ ∃𝑓 ∈ (ℙ ↑𝑚 (1...𝑑))(𝑑 ≤ 4 ∧ 𝑁 = Σ𝑘 ∈ (1...𝑑)(𝑓‘𝑘)))
Theorem	nnsum3primesle9 40210*	Every integer greater than 1 and less than or equal to 8 is the sum of at most 3 primes. (Contributed by AV, 2-Aug-2020.)
⊢ ((𝑁 ∈ (ℤ≥‘2) ∧ 𝑁 ≤ 8) → ∃𝑑 ∈ ℕ ∃𝑓 ∈ (ℙ ↑𝑚 (1...𝑑))(𝑑 ≤ 3 ∧ 𝑁 = Σ𝑘 ∈ (1...𝑑)(𝑓‘𝑘)))
Theorem	nnsum4primesle9 40211*	Every integer greater than 1 and less than or equal to 8 is the sum of at most 4 primes. (Contributed by AV, 24-Jul-2020.) (Proof shortened by AV, 2-Aug-2020.)
⊢ ((𝑁 ∈ (ℤ≥‘2) ∧ 𝑁 ≤ 8) → ∃𝑑 ∈ ℕ ∃𝑓 ∈ (ℙ ↑𝑚 (1...𝑑))(𝑑 ≤ 4 ∧ 𝑁 = Σ𝑘 ∈ (1...𝑑)(𝑓‘𝑘)))
Theorem	nnsum4primesodd 40212*	If the (weak) ternary Goldbach conjecture is valid, then every odd integer greater than 5 is the sum of 3 primes. (Contributed by AV, 2-Jul-2020.)
⊢ (∀𝑚 ∈ Odd (5 < 𝑚 → 𝑚 ∈ GoldbachOdd ) → ((𝑁 ∈ (ℤ≥‘6) ∧ 𝑁 ∈ Odd ) → ∃𝑓 ∈ (ℙ ↑𝑚 (1...3))𝑁 = Σ𝑘 ∈ (1...3)(𝑓‘𝑘)))
Theorem	nnsum4primesoddALTV 40213*	If the (strong) ternary Goldbach conjecture is valid, then every odd integer greater than 7 is the sum of 3 primes. (Contributed by AV, 26-Jul-2020.)
⊢ (∀𝑚 ∈ Odd (7 < 𝑚 → 𝑚 ∈ GoldbachOddALTV ) → ((𝑁 ∈ (ℤ≥‘8) ∧ 𝑁 ∈ Odd ) → ∃𝑓 ∈ (ℙ ↑𝑚 (1...3))𝑁 = Σ𝑘 ∈ (1...3)(𝑓‘𝑘)))
Theorem	evengpop3 40214*	If the (weak) ternary Goldbach conjecture is valid, then every even integer greater than 8 is the sum of an odd Goldbach number and 3. (Contributed by AV, 24-Jul-2020.)
⊢ (∀𝑚 ∈ Odd (5 < 𝑚 → 𝑚 ∈ GoldbachOdd ) → ((𝑁 ∈ (ℤ≥‘9) ∧ 𝑁 ∈ Even ) → ∃𝑜 ∈ GoldbachOdd 𝑁 = (𝑜 + 3)))
Theorem	evengpoap3 40215*	If the (strong) ternary Goldbach conjecture is valid, then every even integer greater than 10 is the sum of an odd Goldbach number and 3. (Contributed by AV, 27-Jul-2020.) (Proof shortened by AV, 15-Sep-2021.)
⊢ (∀𝑚 ∈ Odd (7 < 𝑚 → 𝑚 ∈ GoldbachOddALTV ) → ((𝑁 ∈ (ℤ≥‘;12) ∧ 𝑁 ∈ Even ) → ∃𝑜 ∈ GoldbachOddALTV 𝑁 = (𝑜 + 3)))
Theorem	nnsum4primeseven 40216*	If the (weak) ternary Goldbach conjecture is valid, then every even integer greater than 8 is the sum of 4 primes. (Contributed by AV, 25-Jul-2020.)
⊢ (∀𝑚 ∈ Odd (5 < 𝑚 → 𝑚 ∈ GoldbachOdd ) → ((𝑁 ∈ (ℤ≥‘9) ∧ 𝑁 ∈ Even ) → ∃𝑓 ∈ (ℙ ↑𝑚 (1...4))𝑁 = Σ𝑘 ∈ (1...4)(𝑓‘𝑘)))
Theorem	nnsum4primesevenALTV 40217*	If the (strong) ternary Goldbach conjecture is valid, then every even integer greater than 10 is the sum of 4 primes. (Contributed by AV, 27-Jul-2020.)
⊢ (∀𝑚 ∈ Odd (7 < 𝑚 → 𝑚 ∈ GoldbachOddALTV ) → ((𝑁 ∈ (ℤ≥‘;12) ∧ 𝑁 ∈ Even ) → ∃𝑓 ∈ (ℙ ↑𝑚 (1...4))𝑁 = Σ𝑘 ∈ (1...4)(𝑓‘𝑘)))
Theorem	wtgoldbnnsum4prm 40218*	If the (weak) ternary Goldbach conjecture is valid, then every integer greater than 1 is the sum of at most 4 primes, showing that Schnirelmann's constant would be less than or equal to 4. See corollary 1.1 in [Helfgott] p. 4. (Contributed by AV, 25-Jul-2020.)
⊢ (∀𝑚 ∈ Odd (5 < 𝑚 → 𝑚 ∈ GoldbachOdd ) → ∀𝑛 ∈ (ℤ≥‘2)∃𝑑 ∈ ℕ ∃𝑓 ∈ (ℙ ↑𝑚 (1...𝑑))(𝑑 ≤ 4 ∧ 𝑛 = Σ𝑘 ∈ (1...𝑑)(𝑓‘𝑘)))
Theorem	stgoldbnnsum4prm 40219*	If the (strong) ternary Goldbach conjecture is valid, then every integer greater than 1 is the sum of at most 4 primes. (Contributed by AV, 27-Jul-2020.)
⊢ (∀𝑚 ∈ Odd (7 < 𝑚 → 𝑚 ∈ GoldbachOddALTV ) → ∀𝑛 ∈ (ℤ≥‘2)∃𝑑 ∈ ℕ ∃𝑓 ∈ (ℙ ↑𝑚 (1...𝑑))(𝑑 ≤ 4 ∧ 𝑛 = Σ𝑘 ∈ (1...𝑑)(𝑓‘𝑘)))
Theorem	bgoldbnnsum3prm 40220*	If the binary Goldbach conjecture is valid, then every integer greater than 1 is the sum of at most 3 primes, showing that Schnirelmann's constant would be equal to 3. (Contributed by AV, 2-Aug-2020.)
⊢ (∀𝑚 ∈ Even (4 < 𝑚 → 𝑚 ∈ GoldbachEven ) → ∀𝑛 ∈ (ℤ≥‘2)∃𝑑 ∈ ℕ ∃𝑓 ∈ (ℙ ↑𝑚 (1...𝑑))(𝑑 ≤ 3 ∧ 𝑛 = Σ𝑘 ∈ (1...𝑑)(𝑓‘𝑘)))
Theorem	bgoldbtbndlem1 40221	Lemma 1 for bgoldbtbnd 40225: the odd numbers between 7 and 13 (exclusive) are (strong) odd Goldbach numbers. (Contributed by AV, 29-Jul-2020.)
⊢ ((𝑁 ∈ Odd ∧ 7 < 𝑁 ∧ 𝑁 ∈ (7[,);13)) → 𝑁 ∈ GoldbachOddALTV )
Theorem	bgoldbtbndlem2 40222*	Lemma 2 for bgoldbtbnd 40225. (Contributed by AV, 1-Aug-2020.)
⊢ (𝜑 → 𝑀 ∈ (ℤ≥‘;11))    &   ⊢ (𝜑 → 𝑁 ∈ (ℤ≥‘;11))    &   ⊢ (𝜑 → ∀𝑛 ∈ Even ((4 < 𝑛 ∧ 𝑛 < 𝑁) → 𝑛 ∈ GoldbachEven ))    &   ⊢ (𝜑 → 𝐷 ∈ (ℤ≥‘3))    &   ⊢ (𝜑 → 𝐹 ∈ (RePart‘𝐷))    &   ⊢ (𝜑 → ∀𝑖 ∈ (0..^𝐷)((𝐹‘𝑖) ∈ (ℙ ∖ {2}) ∧ ((𝐹‘(𝑖 + 1)) − (𝐹‘𝑖)) < (𝑁 − 4) ∧ 4 < ((𝐹‘(𝑖 + 1)) − (𝐹‘𝑖))))    &   ⊢ (𝜑 → (𝐹‘0) = 7)    &   ⊢ (𝜑 → (𝐹‘1) = ;13)    &   ⊢ (𝜑 → 𝑀 < (𝐹‘𝐷))    &   ⊢ 𝑆 = (𝑋 − (𝐹‘(𝐼 − 1)))    ⇒   ⊢ ((𝜑 ∧ 𝑋 ∈ Odd ∧ 𝐼 ∈ (1..^𝐷)) → ((𝑋 ∈ ((𝐹‘𝐼)[,)(𝐹‘(𝐼 + 1))) ∧ (𝑋 − (𝐹‘𝐼)) ≤ 4) → (𝑆 ∈ Even ∧ 𝑆 < 𝑁 ∧ 4 < 𝑆)))
Theorem	bgoldbtbndlem3 40223*	Lemma 3 for bgoldbtbnd 40225. (Contributed by AV, 1-Aug-2020.)
⊢ (𝜑 → 𝑀 ∈ (ℤ≥‘;11))    &   ⊢ (𝜑 → 𝑁 ∈ (ℤ≥‘;11))    &   ⊢ (𝜑 → ∀𝑛 ∈ Even ((4 < 𝑛 ∧ 𝑛 < 𝑁) → 𝑛 ∈ GoldbachEven ))    &   ⊢ (𝜑 → 𝐷 ∈ (ℤ≥‘3))    &   ⊢ (𝜑 → 𝐹 ∈ (RePart‘𝐷))    &   ⊢ (𝜑 → ∀𝑖 ∈ (0..^𝐷)((𝐹‘𝑖) ∈ (ℙ ∖ {2}) ∧ ((𝐹‘(𝑖 + 1)) − (𝐹‘𝑖)) < (𝑁 − 4) ∧ 4 < ((𝐹‘(𝑖 + 1)) − (𝐹‘𝑖))))    &   ⊢ (𝜑 → (𝐹‘0) = 7)    &   ⊢ (𝜑 → (𝐹‘1) = ;13)    &   ⊢ (𝜑 → 𝑀 < (𝐹‘𝐷))    &   ⊢ (𝜑 → (𝐹‘𝐷) ∈ ℝ)    &   ⊢ 𝑆 = (𝑋 − (𝐹‘𝐼))    ⇒   ⊢ ((𝜑 ∧ 𝑋 ∈ Odd ∧ 𝐼 ∈ (1..^𝐷)) → ((𝑋 ∈ ((𝐹‘𝐼)[,)(𝐹‘(𝐼 + 1))) ∧ 4 < 𝑆) → (𝑆 ∈ Even ∧ 𝑆 < 𝑁 ∧ 4 < 𝑆)))
Theorem	bgoldbtbndlem4 40224*	Lemma 4 for bgoldbtbnd 40225. (Contributed by AV, 1-Aug-2020.)
⊢ (𝜑 → 𝑀 ∈ (ℤ≥‘;11))    &   ⊢ (𝜑 → 𝑁 ∈ (ℤ≥‘;11))    &   ⊢ (𝜑 → ∀𝑛 ∈ Even ((4 < 𝑛 ∧ 𝑛 < 𝑁) → 𝑛 ∈ GoldbachEven ))    &   ⊢ (𝜑 → 𝐷 ∈ (ℤ≥‘3))    &   ⊢ (𝜑 → 𝐹 ∈ (RePart‘𝐷))    &   ⊢ (𝜑 → ∀𝑖 ∈ (0..^𝐷)((𝐹‘𝑖) ∈ (ℙ ∖ {2}) ∧ ((𝐹‘(𝑖 + 1)) − (𝐹‘𝑖)) < (𝑁 − 4) ∧ 4 < ((𝐹‘(𝑖 + 1)) − (𝐹‘𝑖))))    &   ⊢ (𝜑 → (𝐹‘0) = 7)    &   ⊢ (𝜑 → (𝐹‘1) = ;13)    &   ⊢ (𝜑 → 𝑀 < (𝐹‘𝐷))    &   ⊢ (𝜑 → (𝐹‘𝐷) ∈ ℝ)    ⇒   ⊢ (((𝜑 ∧ 𝐼 ∈ (1..^𝐷)) ∧ 𝑋 ∈ Odd ) → ((𝑋 ∈ ((𝐹‘𝐼)[,)(𝐹‘(𝐼 + 1))) ∧ (𝑋 − (𝐹‘𝐼)) ≤ 4) → ∃𝑝 ∈ ℙ ∃𝑞 ∈ ℙ ∃𝑟 ∈ ℙ ((𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑟 ∈ Odd ) ∧ 𝑋 = ((𝑝 + 𝑞) + 𝑟))))
Theorem	bgoldbtbnd 40225*	If the binary Goldbach conjecture is valid up to an integer 𝑁, and there is a series ("ladder") of primes with a difference of at most 𝑁 up to an integer 𝑀, then the strong ternary Goldbach conjecture is valid up to 𝑀, see section 1.2.2 in [Helfgott] p. 4 with N = 4 x 10^18, taken from [OeSilva], and M = 8.875 x 10^30. (Contributed by AV, 1-Aug-2020.)
⊢ (𝜑 → 𝑀 ∈ (ℤ≥‘;11))    &   ⊢ (𝜑 → 𝑁 ∈ (ℤ≥‘;11))    &   ⊢ (𝜑 → ∀𝑛 ∈ Even ((4 < 𝑛 ∧ 𝑛 < 𝑁) → 𝑛 ∈ GoldbachEven ))    &   ⊢ (𝜑 → 𝐷 ∈ (ℤ≥‘3))    &   ⊢ (𝜑 → 𝐹 ∈ (RePart‘𝐷))    &   ⊢ (𝜑 → ∀𝑖 ∈ (0..^𝐷)((𝐹‘𝑖) ∈ (ℙ ∖ {2}) ∧ ((𝐹‘(𝑖 + 1)) − (𝐹‘𝑖)) < (𝑁 − 4) ∧ 4 < ((𝐹‘(𝑖 + 1)) − (𝐹‘𝑖))))    &   ⊢ (𝜑 → (𝐹‘0) = 7)    &   ⊢ (𝜑 → (𝐹‘1) = ;13)    &   ⊢ (𝜑 → 𝑀 < (𝐹‘𝐷))    &   ⊢ (𝜑 → (𝐹‘𝐷) ∈ ℝ)    ⇒   ⊢ (𝜑 → ∀𝑛 ∈ Odd ((7 < 𝑛 ∧ 𝑛 < 𝑀) → 𝑛 ∈ GoldbachOddALTV ))
Axiom	ax-bgbltosilva 40226	The binary Goldbach conjecture is valid for all even numbers less than or equal to 4x10^18, see result of [OeSilva] p. ?. Temporarily provided as "axiom". (Contributed by AV, 3-Aug-2020.) (Revised by AV, 9-Sep-2021.)
⊢ ((𝑁 ∈ Even ∧ 4 < 𝑁 ∧ 𝑁 ≤ (4 · (;10↑;18))) → 𝑁 ∈ GoldbachEven )
Theorem	bgoldbachlt 40227*	The binary Goldbach conjecture is valid for small even numbers (i.e. for all even numbers less than or equal to a fixed big 𝑚). This is verified for m = 4 x 10^18 by Oliveira e Silva, see ax-bgbltosilva 40226. (Contributed by AV, 3-Aug-2020.) (Revised by AV, 9-Sep-2021.)
⊢ ∃𝑚 ∈ ℕ ((4 · (;10↑;18)) ≤ 𝑚 ∧ ∀𝑛 ∈ Even ((4 < 𝑛 ∧ 𝑛 < 𝑚) → 𝑛 ∈ GoldbachEven ))
Axiom	ax-hgprmladder 40228	There is a partition ("ladder") of primes from 7 to 8.8 x 10^30 with parts ("rungs") having lengths of at least 4 and at most N - 4, see section 1.2.2 in [Helfgott] p. 4. Temporarily provided as "axiom". (Contributed by AV, 3-Aug-2020.) (Revised by AV, 9-Sep-2021.)
⊢ ∃𝑑 ∈ (ℤ≥‘3)∃𝑓 ∈ (RePart‘𝑑)(((𝑓‘0) = 7 ∧ (𝑓‘1) = ;13 ∧ (𝑓‘𝑑) = (;89 · (;10↑;29))) ∧ ∀𝑖 ∈ (0..^𝑑)((𝑓‘𝑖) ∈ (ℙ ∖ {2}) ∧ ((𝑓‘(𝑖 + 1)) − (𝑓‘𝑖)) < ((4 · (;10↑;18)) − 4) ∧ 4 < ((𝑓‘(𝑖 + 1)) − (𝑓‘𝑖))))
Theorem	tgblthelfgott 40229	The ternary Goldbach conjecture is valid for all odd numbers less than 8.8 x 10^30 (actually 8.875694 x 10^30, see section 1.2.2 in [Helfgott] p. 4, using bgoldbachlt 40227, ax-hgprmladder 40228 and bgoldbtbnd 40225. (Contributed by AV, 4-Aug-2020.) (Revised by AV, 9-Sep-2021.)
⊢ ((𝑁 ∈ Odd ∧ 7 < 𝑁 ∧ 𝑁 < (;88 · (;10↑;29))) → 𝑁 ∈ GoldbachOddALTV )
Theorem	tgoldbachlt 40230*	The ternary Goldbach conjecture is valid for small odd numbers (i.e. for all odd numbers less than a fixed big 𝑚 greater than 8 x 10^30). This is verified for m = 8.875694 x 10^30 by Helfgott, see tgblthelfgott 40229. (Contributed by AV, 4-Aug-2020.) (Revised by AV, 9-Sep-2021.)
⊢ ∃𝑚 ∈ ℕ ((8 · (;10↑;30)) < 𝑚 ∧ ∀𝑛 ∈ Odd ((7 < 𝑛 ∧ 𝑛 < 𝑚) → 𝑛 ∈ GoldbachOddALTV ))
Axiom	ax-tgoldbachgt 40231*	The ternary Goldbach conjecture is valid for big odd numbers (i.e. for all odd numbers greater than a fixed 𝑚). This is proven by Helfgott (see section 7.4 in [Helfgott] p. 70) for m = 10^27. Temporarily provided as "axiom". (Contributed by AV, 2-Aug-2020.) (Revised by AV, 9-Sep-2021.)
⊢ ∃𝑚 ∈ ℕ (𝑚 ≤ (;10↑;27) ∧ ∀𝑛 ∈ Odd (𝑚 < 𝑛 → 𝑛 ∈ GoldbachOddALTV ))
Theorem	tgoldbach 40232	The ternary Goldbach conjecture is valid. Main theorem in [Helfgott] p. 2. This follows from tgoldbachlt 40230 and ax-tgoldbachgt 40231. (Contributed by AV, 2-Aug-2020.) (Revised by AV, 9-Sep-2021.)
⊢ ∀𝑛 ∈ Odd (7 < 𝑛 → 𝑛 ∈ GoldbachOddALTV )
Axiom	ax-bgbltosilvaOLD 40233	Obsolete version of ax-bgbltosilva 40226 as of 9-Sep-2021. (Contributed by AV, 3-Aug-2020.) (New usage is discouraged.)
⊢ ((𝑁 ∈ Even ∧ 4 < 𝑁 ∧ 𝑁 ≤ (4 · (10↑;18))) → 𝑁 ∈ GoldbachEven )
Theorem	bgoldbachltOLD 40234*	Obsolete version of bgoldbachlt 40227 as of 9-Sep-2021. (Contributed by AV, 3-Aug-2020.) (Proof modification is discouraged.) (New usage is discouraged.)
⊢ ∃𝑚 ∈ ℕ ((4 · (10↑;18)) ≤ 𝑚 ∧ ∀𝑛 ∈ Even ((4 < 𝑛 ∧ 𝑛 < 𝑚) → 𝑛 ∈ GoldbachEven ))
Axiom	ax-hgprmladderOLD 40235	Obsolete version of ax-hgprmladder 40228 as of 9-Sep-2021. (Contributed by AV, 3-Aug-2020.) (New usage is discouraged.)
⊢ ∃𝑑 ∈ (ℤ≥‘3)∃𝑓 ∈ (RePart‘𝑑)(((𝑓‘0) = 7 ∧ (𝑓‘1) = ;13 ∧ (𝑓‘𝑑) = (;89 · (10↑;29))) ∧ ∀𝑖 ∈ (0..^𝑑)((𝑓‘𝑖) ∈ (ℙ ∖ {2}) ∧ ((𝑓‘(𝑖 + 1)) − (𝑓‘𝑖)) < ((4 · (10↑;18)) − 4) ∧ 4 < ((𝑓‘(𝑖 + 1)) − (𝑓‘𝑖))))
Theorem	tgblthelfgottOLD 40236	Obsolete version of tgblthelfgott 40229 as of 9-Sep-2021. (Contributed by AV, 4-Aug-2020.) (Proof modification is discouraged.) (New usage is discouraged.)
⊢ ((𝑁 ∈ Odd ∧ 7 < 𝑁 ∧ 𝑁 < (;88 · (10↑;29))) → 𝑁 ∈ GoldbachOddALTV )
Theorem	tgoldbachltOLD 40237*	Obsolete version of tgoldbachlt 40230 as of 9-Sep-2021. (Contributed by AV, 4-Aug-2020.) (Proof modification is discouraged.) (New usage is discouraged.)
⊢ ∃𝑚 ∈ ℕ ((8 · (10↑;30)) < 𝑚 ∧ ∀𝑛 ∈ Odd ((7 < 𝑛 ∧ 𝑛 < 𝑚) → 𝑛 ∈ GoldbachOddALTV ))
Axiom	ax-tgoldbachgtOLD 40238*	Obsolete version of ax-tgoldbachgt 40231 as of 9-Sep-2021. (Contributed by AV, 2-Aug-2020.) (New usage is discouraged.)
⊢ ∃𝑚 ∈ ℕ (𝑚 ≤ (10↑;27) ∧ ∀𝑛 ∈ Odd (𝑚 < 𝑛 → 𝑛 ∈ GoldbachOddALTV ))
Theorem	tgoldbachOLD 40239	Obsolete version of tgoldbach 40232 as of 9-Sep-2021. (Contributed by AV, 2-Aug-2020.) (Proof modification is discouraged.) (New usage is discouraged.)
⊢ ∀𝑛 ∈ Odd (7 < 𝑛 → 𝑛 ∈ GoldbachOddALTV )
21.34.6  Words over a set (extension)
21.34.6.1  Truncated words
Theorem	wrdred1 40240	A word truncated by a symbol is a word. (Contributed by AV, 29-Jan-2021.)
⊢ (𝐹 ∈ Word 𝑆 → (𝐹 ↾ (0..^((#‘𝐹) − 1))) ∈ Word 𝑆)
Theorem	wrdred1hash 40241	The length of a word truncated by a symbol. (Contributed by Alexander van der Vekens, 1-Nov-2017.) (Revised by AV, 29-Jan-2021.)
⊢ ((𝐹 ∈ Word 𝑆 ∧ 1 ≤ (#‘𝐹)) → (#‘(𝐹 ↾ (0..^((#‘𝐹) − 1)))) = ((#‘𝐹) − 1))
21.34.6.2  Last symbol of a word (extension)
Theorem	lswn0 40242	The last symbol of a not empty word exists. The empty set must be excluded as symbol, because otherwise, it cannot be distinguished between valid cases (∅ is the last symbol) and invalid cases (∅ means that no last symbol exists. This is because of the special definition of a function in set.mm. (Contributed by Alexander van der Vekens, 18-Mar-2018.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ ∅ ∉ 𝑉 ∧ (#‘𝑊) ≠ 0) → ( lastS ‘𝑊) ≠ ∅)
21.34.6.3  Concatenations with singleton words (extension)
Theorem	ccatw2s1cl 40243	The concatenation of a word with two singleton words is a word. (Contributed by Alexander van der Vekens, 22-Sep-2018.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → ((𝑊 ++ ⟨“𝑋”⟩) ++ ⟨“𝑌”⟩) ∈ Word 𝑉)
21.34.6.4  Prefixes of a word In https://www.allacronyms.com/prefix/abbreviated, "pfx" is proposed as abbreviation for "prefix". Regarding the meaning of "prefix", it is different in computer science (automata theory/formal languages) compared with linguistics: in linguistics, a prefix has a meaning (see Wikipedia "Prefix" https://en.wikipedia.org/wiki/Prefix), whereas in computer science, a prefix is an arbitrary substring/subword starting at the beginning of a string/word (see Wikipedia "Substring" https://en.wikipedia.org/wiki/Substring#Prefix or https://math.stackexchange.com/questions/2190559/ is-there-standard-terminology-notation-for-the-prefix-of-a-word ).
Syntax	cpfx 40244	Syntax for the prefix operator.
class prefix
Definition	df-pfx 40245*	Define an operation which extracts prefixes of words, i.e. subwords starting at the beginning of a word. Definition in section 9.1 of [AhoHopUll] p. 318. "pfx" is used as label fragment. (Contributed by AV, 2-May-2020.)
⊢ prefix = (𝑠 ∈ V, 𝑙 ∈ ℕ0 ↦ (𝑠 substr ⟨0, 𝑙⟩))
Theorem	pfxval 40246	Value of a prefix. (Contributed by AV, 2-May-2020.)
⊢ ((𝑆 ∈ 𝑉 ∧ 𝐿 ∈ ℕ0) → (𝑆 prefix 𝐿) = (𝑆 substr ⟨0, 𝐿⟩))
Theorem	pfx00 40247	A zero length prefix. (Contributed by AV, 2-May-2020.)
⊢ (𝑆 prefix 0) = ∅
Theorem	pfx0 40248	A prefix of an empty set is always the empty set. (Contributed by AV, 3-May-2020.)
⊢ (∅ prefix 𝐿) = ∅
Theorem	pfxcl 40249	Closure of the prefix extractor. (Contributed by AV, 2-May-2020.)
⊢ (𝑆 ∈ Word 𝐴 → (𝑆 prefix 𝐿) ∈ Word 𝐴)
Theorem	pfxmpt 40250*	Value of the prefix extractor as mapping. (Contributed by AV, 2-May-2020.)
⊢ ((𝑆 ∈ Word 𝐴 ∧ 𝐿 ∈ (0...(#‘𝑆))) → (𝑆 prefix 𝐿) = (𝑥 ∈ (0..^𝐿) ↦ (𝑆‘𝑥)))
Theorem	pfxres 40251	Value of the prefix extractor as restriction. Could replace swrd0val 13273. (Contributed by AV, 2-May-2020.)
⊢ ((𝑆 ∈ Word 𝐴 ∧ 𝐿 ∈ (0...(#‘𝑆))) → (𝑆 prefix 𝐿) = (𝑆 ↾ (0..^𝐿)))
Theorem	pfxf 40252	A prefix of a word is a function from a half-open range of nonnegative integers of the same length as the prefix to the set of symbols for the original word. Could replace swrd0f 13279. (Contributed by AV, 2-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝐿 ∈ (0...(#‘𝑊))) → (𝑊 prefix 𝐿):(0..^𝐿)⟶𝑉)
Theorem	pfxfn 40253	Value of the prefix extractor as function with domain. (Contributed by AV, 2-May-2020.)
⊢ ((𝑆 ∈ Word 𝑉 ∧ 𝐿 ∈ (0...(#‘𝑆))) → (𝑆 prefix 𝐿) Fn (0..^𝐿))
Theorem	pfxlen 40254	Length of a prefix. Could replace swrd0len 13274. (Contributed by AV, 2-May-2020.)
⊢ ((𝑆 ∈ Word 𝐴 ∧ 𝐿 ∈ (0...(#‘𝑆))) → (#‘(𝑆 prefix 𝐿)) = 𝐿)
Theorem	pfxid 40255	A word is a prefix of itself. (Contributed by AV, 2-May-2020.)
⊢ (𝑆 ∈ Word 𝐴 → (𝑆 prefix (#‘𝑆)) = 𝑆)
Theorem	pfxrn 40256	The range of a prefix of a word is a subset of the set of symbols for the word. (Contributed by AV, 2-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝐿 ∈ (0...(#‘𝑊))) → ran (𝑊 prefix 𝐿) ⊆ 𝑉)
Theorem	pfxn0 40257	A prefix consisting of at least one symbol is not empty. Could replace swrdn0 13282. (Contributed by AV, 2-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝐿 ∈ ℕ ∧ 𝐿 ≤ (#‘𝑊)) → (𝑊 prefix 𝐿) ≠ ∅)
Theorem	pfxnd 40258	The value of the prefix extractor is the empty set (undefined) if the argument is not within the range of the word. (Contributed by AV, 3-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝐿 ∈ ℕ0 ∧ (#‘𝑊) < 𝐿) → (𝑊 prefix 𝐿) = ∅)
Theorem	pfxlen0 40259	Length of a prefix of a word reduced by a single symbol. Could replace swrd0len0 13288. TODO-AV: Really useful? swrd0len0 13288 is only used in wwlknred 26251. (Contributed by AV, 3-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝐿 ∈ ℕ0 ∧ (#‘𝑊) = (𝐿 + 1)) → (#‘(𝑊 prefix 𝐿)) = 𝐿)
Theorem	addlenrevpfx 40260	The sum of the lengths of two reversed parts of a word is the length of the word. (Contributed by AV, 3-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑀 ∈ (0...(#‘𝑊))) → ((#‘(𝑊 substr ⟨𝑀, (#‘𝑊)⟩)) + (#‘(𝑊 prefix 𝑀))) = (#‘𝑊))
Theorem	addlenpfx 40261	The sum of the lengths of two parts of a word is the length of the word. (Contributed by AV, 3-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑀 ∈ (0...(#‘𝑊))) → ((#‘(𝑊 prefix 𝑀)) + (#‘(𝑊 substr ⟨𝑀, (#‘𝑊)⟩))) = (#‘𝑊))
Theorem	pfxfv 40262	A symbol in a prefix of a word, indexed using the prefix' indices. Could replace swrd0fv 13291. (Contributed by AV, 3-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝐿 ∈ (0...(#‘𝑊)) ∧ 𝐼 ∈ (0..^𝐿)) → ((𝑊 prefix 𝐿)‘𝐼) = (𝑊‘𝐼))
Theorem	pfxfv0 40263	The first symbol in a prefix of a word. Could replace swrd0fv0 13292. (Contributed by AV, 3-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝐿 ∈ (1...(#‘𝑊))) → ((𝑊 prefix 𝐿)‘0) = (𝑊‘0))
Theorem	pfxtrcfv 40264	A symbol in a word truncated by one symbol. Could replace swrdtrcfv 13293. (Contributed by AV, 3-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑊 ≠ ∅ ∧ 𝐼 ∈ (0..^((#‘𝑊) − 1))) → ((𝑊 prefix ((#‘𝑊) − 1))‘𝐼) = (𝑊‘𝐼))
Theorem	pfxtrcfv0 40265	The first symbol in a word truncated by one symbol. Could replace swrdtrcfv0 13294. (Contributed by AV, 3-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ≤ (#‘𝑊)) → ((𝑊 prefix ((#‘𝑊) − 1))‘0) = (𝑊‘0))
Theorem	pfxfvlsw 40266	The last symbol in a (not empty) prefix of a word. Could replace swrd0fvlsw 13295. (Contributed by AV, 3-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝐿 ∈ (1...(#‘𝑊))) → ( lastS ‘(𝑊 prefix 𝐿)) = (𝑊‘(𝐿 − 1)))
Theorem	pfxeq 40267*	The prefixes of two words are equal iff they have the same length and the same symbols at each position. Could replace swrdeq 13296. (Contributed by AV, 4-May-2020.)
⊢ (((𝑊 ∈ Word 𝑉 ∧ 𝑈 ∈ Word 𝑉) ∧ (𝑀 ∈ ℕ0 ∧ 𝑁 ∈ ℕ0) ∧ (𝑀 ≤ (#‘𝑊) ∧ 𝑁 ≤ (#‘𝑈))) → ((𝑊 prefix 𝑀) = (𝑈 prefix 𝑁) ↔ (𝑀 = 𝑁 ∧ ∀𝑖 ∈ (0..^𝑀)(𝑊‘𝑖) = (𝑈‘𝑖))))
Theorem	pfxtrcfvl 40268	The last symbol in a word truncated by one symbol. Could replace swrdtrcfvl 13302. (Contributed by AV, 5-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ≤ (#‘𝑊)) → ( lastS ‘(𝑊 prefix ((#‘𝑊) − 1))) = (𝑊‘((#‘𝑊) − 2)))
Theorem	pfxsuffeqwrdeq 40269	Two words are equal if and only if they have the same prefix and the same suffix. Could replace 2swrdeqwrdeq 13305. (Contributed by AV, 5-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑆 ∈ Word 𝑉 ∧ 𝐼 ∈ (0..^(#‘𝑊))) → (𝑊 = 𝑆 ↔ ((#‘𝑊) = (#‘𝑆) ∧ ((𝑊 prefix 𝐼) = (𝑆 prefix 𝐼) ∧ (𝑊 substr ⟨𝐼, (#‘𝑊)⟩) = (𝑆 substr ⟨𝐼, (#‘𝑊)⟩)))))
Theorem	pfxsuff1eqwrdeq 40270	Two (nonempty) words are equal if and only if they have the same prefix and the same single symbol suffix. Could replace 2swrd1eqwrdeq 13306. (Contributed by AV, 6-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑈 ∈ Word 𝑉 ∧ 0 < (#‘𝑊)) → (𝑊 = 𝑈 ↔ ((#‘𝑊) = (#‘𝑈) ∧ ((𝑊 prefix ((#‘𝑊) − 1)) = (𝑈 prefix ((#‘𝑊) − 1)) ∧ ( lastS ‘𝑊) = ( lastS ‘𝑈)))))
Theorem	disjwrdpfx 40271*	Sets of words are disjoint if each set contains extensions of distinct words of a fixed length. Could replace disjxwrd 13307. (Contributed by AV, 6-May-2020.)
⊢ Disj 𝑦 ∈ 𝑊 {𝑥 ∈ Word 𝑉 ∣ (𝑥 prefix 𝑁) = 𝑦}
Theorem	ccatpfx 40272	Joining a prefix with an adjacent subword makes a longer prefix. (Contributed by AV, 7-May-2020.)
⊢ ((𝑆 ∈ Word 𝐴 ∧ 𝑌 ∈ (0...𝑍) ∧ 𝑍 ∈ (0...(#‘𝑆))) → ((𝑆 prefix 𝑌) ++ (𝑆 substr ⟨𝑌, 𝑍⟩)) = (𝑆 prefix 𝑍))
Theorem	pfxccat1 40273	Recover the left half of a concatenated word. Could replace swrdccat1 13309. (Contributed by AV, 6-May-2020.)
⊢ ((𝑆 ∈ Word 𝐵 ∧ 𝑇 ∈ Word 𝐵) → ((𝑆 ++ 𝑇) prefix (#‘𝑆)) = 𝑆)
Theorem	pfx1 40274	A prefix of length 1. (Contributed by AV, 15-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑊 ≠ ∅) → (𝑊 prefix 1) = ⟨“(𝑊‘0)”⟩)
Theorem	pfx2 40275	A prefix of length 2. (Contributed by AV, 15-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ≤ (#‘𝑊)) → (𝑊 prefix 2) = ⟨“(𝑊‘0)(𝑊‘1)”⟩)
Theorem	pfxswrd 40276	A prefix of a subword. Could replace swrd0swrd 13313. (Contributed by AV, 8-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑁 ∈ (0...(#‘𝑊)) ∧ 𝑀 ∈ (0...𝑁)) → (𝐿 ∈ (0...(𝑁 − 𝑀)) → ((𝑊 substr ⟨𝑀, 𝑁⟩) prefix 𝐿) = (𝑊 substr ⟨𝑀, (𝑀 + 𝐿)⟩)))
Theorem	swrdpfx 40277	A subword of a prefix. Could replace swrdswrd0 13314. (Contributed by AV, 8-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑁 ∈ (0...(#‘𝑊))) → ((𝐾 ∈ (0...𝑁) ∧ 𝐿 ∈ (𝐾...𝑁)) → ((𝑊 prefix 𝑁) substr ⟨𝐾, 𝐿⟩) = (𝑊 substr ⟨𝐾, 𝐿⟩)))
Theorem	pfxpfx 40278	A prefix of a prefix. Could replace swrd0swrd0 13315. (Contributed by AV, 8-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑁 ∈ (0...(#‘𝑊)) ∧ 𝐿 ∈ (0...𝑁)) → ((𝑊 prefix 𝑁) prefix 𝐿) = (𝑊 prefix 𝐿))
Theorem	pfxpfxid 40279	A prefix of a prefix with the same length is the prefix. Could replace swrd0swrdid 13316. (Contributed by AV, 8-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑁 ∈ (0...(#‘𝑊))) → ((𝑊 prefix 𝑁) prefix 𝑁) = (𝑊 prefix 𝑁))
Theorem	pfxcctswrd 40280	The concatenation of the prefix of a word and the rest of the word yields the word itself. Could replace wrdcctswrd 13317. (Contributed by AV, 9-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑀 ∈ (0...(#‘𝑊))) → ((𝑊 prefix 𝑀) ++ (𝑊 substr ⟨𝑀, (#‘𝑊)⟩)) = 𝑊)
Theorem	lenpfxcctswrd 40281	The length of the concatenation of the prefix of a word and the rest of the word is the length of the word. Could replace lencctswrd 13318. (Contributed by AV, 9-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑀 ∈ (0...(#‘𝑊))) → (#‘((𝑊 prefix 𝑀) ++ (𝑊 substr ⟨𝑀, (#‘𝑊)⟩))) = (#‘𝑊))
Theorem	lenrevpfxcctswrd 40282	The length of the concatenation of the rest of a word and the prefix of the word is the length of the word. Could replace lenrevcctswrd 13319. (Contributed by AV, 9-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑀 ∈ (0...(#‘𝑊))) → (#‘((𝑊 substr ⟨𝑀, (#‘𝑊)⟩) ++ (𝑊 prefix 𝑀))) = (#‘𝑊))
Theorem	pfxlswccat 40283	Reconstruct a nonempty word from its prefix and last symbol. Could replace swrdccatwrd 13320. (Contributed by AV, 9-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑊 ≠ ∅) → ((𝑊 prefix ((#‘𝑊) − 1)) ++ ⟨“( lastS ‘𝑊)”⟩) = 𝑊)
Theorem	ccats1pfxeq 40284	The last symbol of a word concatenated with the word with the last symbol removed having results in the word itself. Could replace ccats1swrdeq 13321. (Contributed by AV, 9-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑈 ∈ Word 𝑉 ∧ (#‘𝑈) = ((#‘𝑊) + 1)) → (𝑊 = (𝑈 prefix (#‘𝑊)) → 𝑈 = (𝑊 ++ ⟨“( lastS ‘𝑈)”⟩)))
Theorem	ccats1pfxeqrex 40285*	There exists a symbol such that its concatenation with the prefix obtained by deleting the last symbol of a nonempty word results in the word itself. Could replace ccats1swrdeqrex 13330. (Contributed by AV, 9-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑈 ∈ Word 𝑉 ∧ (#‘𝑈) = ((#‘𝑊) + 1)) → (𝑊 = (𝑈 prefix (#‘𝑊)) → ∃𝑠 ∈ 𝑉 𝑈 = (𝑊 ++ ⟨“𝑠”⟩)))
Theorem	pfxccatin12lem1 40286	Lemma 1 for pfxccatin12 40288. Could replace swrdccatin12lem2b 13337. (Contributed by AV, 9-May-2020.)
⊢ ((𝑀 ∈ (0...𝐿) ∧ 𝑁 ∈ (𝐿...𝑋)) → ((𝐾 ∈ (0..^(𝑁 − 𝑀)) ∧ ¬ 𝐾 ∈ (0..^(𝐿 − 𝑀))) → (𝐾 − (𝐿 − 𝑀)) ∈ (0..^(𝑁 − 𝐿))))
Theorem	pfxccatin12lem2 40287	Lemma 2 for pfxccatin12 40288. Could replace swrdccatin12lem2 13340. (Contributed by AV, 9-May-2020.)
⊢ 𝐿 = (#‘𝐴)    ⇒   ⊢ (((𝐴 ∈ Word 𝑉 ∧ 𝐵 ∈ Word 𝑉) ∧ (𝑀 ∈ (0...𝐿) ∧ 𝑁 ∈ (𝐿...(𝐿 + (#‘𝐵))))) → ((𝐾 ∈ (0..^(𝑁 − 𝑀)) ∧ ¬ 𝐾 ∈ (0..^(𝐿 − 𝑀))) → (((𝐴 ++ 𝐵) substr ⟨𝑀, 𝑁⟩)‘𝐾) = ((𝐵 prefix (𝑁 − 𝐿))‘(𝐾 − (#‘(𝐴 substr ⟨𝑀, 𝐿⟩))))))
Theorem	pfxccatin12 40288	The subword of a concatenation of two words within both of the concatenated words. Could replace swrdccatin12 13342. (Contributed by AV, 9-May-2020.)
⊢ 𝐿 = (#‘𝐴)    ⇒   ⊢ ((𝐴 ∈ Word 𝑉 ∧ 𝐵 ∈ Word 𝑉) → ((𝑀 ∈ (0...𝐿) ∧ 𝑁 ∈ (𝐿...(𝐿 + (#‘𝐵)))) → ((𝐴 ++ 𝐵) substr ⟨𝑀, 𝑁⟩) = ((𝐴 substr ⟨𝑀, 𝐿⟩) ++ (𝐵 prefix (𝑁 − 𝐿)))))
Theorem	pfxccat3 40289	The subword of a concatenation is either a subword of the first concatenated word or a subword of the second concatenated word or a concatenation of a suffix of the first word with a prefix of the second word. Could replace swrdccat3 13343. (Contributed by AV, 10-May-2020.)
⊢ 𝐿 = (#‘𝐴)    ⇒   ⊢ ((𝐴 ∈ Word 𝑉 ∧ 𝐵 ∈ Word 𝑉) → ((𝑀 ∈ (0...𝑁) ∧ 𝑁 ∈ (0...(𝐿 + (#‘𝐵)))) → ((𝐴 ++ 𝐵) substr ⟨𝑀, 𝑁⟩) = if(𝑁 ≤ 𝐿, (𝐴 substr ⟨𝑀, 𝑁⟩), if(𝐿 ≤ 𝑀, (𝐵 substr ⟨(𝑀 − 𝐿), (𝑁 − 𝐿)⟩), ((𝐴 substr ⟨𝑀, 𝐿⟩) ++ (𝐵 prefix (𝑁 − 𝐿)))))))
Theorem	pfxccatpfx1 40290	A prefix of a concatenation being a prefix of the first concatenated word. (Contributed by AV, 10-May-2020.)
⊢ 𝐿 = (#‘𝐴)    ⇒   ⊢ ((𝐴 ∈ Word 𝑉 ∧ 𝐵 ∈ Word 𝑉 ∧ 𝑁 ∈ (0...𝐿)) → ((𝐴 ++ 𝐵) prefix 𝑁) = (𝐴 prefix 𝑁))
Theorem	pfxccatpfx2 40291	A prefix of a concatenation of two words being the first word concatenated with a prefix of the second word. (Contributed by AV, 10-May-2020.)
⊢ 𝐿 = (#‘𝐴)    &   ⊢ 𝑀 = (#‘𝐵)    ⇒   ⊢ ((𝐴 ∈ Word 𝑉 ∧ 𝐵 ∈ Word 𝑉 ∧ 𝑁 ∈ ((𝐿 + 1)...(𝐿 + 𝑀))) → ((𝐴 ++ 𝐵) prefix 𝑁) = (𝐴 ++ (𝐵 prefix (𝑁 − 𝐿))))
Theorem	pfxccat3a 40292	A prefix of a concatenation is either a prefix of the first concatenated word or a concatenation of the first word with a prefix of the second word. Could replace swrdccat3a 13345. (Contributed by AV, 10-May-2020.)
⊢ 𝐿 = (#‘𝐴)    &   ⊢ 𝑀 = (#‘𝐵)    ⇒   ⊢ ((𝐴 ∈ Word 𝑉 ∧ 𝐵 ∈ Word 𝑉) → (𝑁 ∈ (0...(𝐿 + 𝑀)) → ((𝐴 ++ 𝐵) prefix 𝑁) = if(𝑁 ≤ 𝐿, (𝐴 prefix 𝑁), (𝐴 ++ (𝐵 prefix (𝑁 − 𝐿))))))
Theorem	pfxccatid 40293	A prefix of a concatenation of length of the first concatenated word is the first word itself. Could replace swrdccatid 13348. (Contributed by AV, 10-May-2020.)
⊢ ((𝐴 ∈ Word 𝑉 ∧ 𝐵 ∈ Word 𝑉 ∧ 𝑁 = (#‘𝐴)) → ((𝐴 ++ 𝐵) prefix 𝑁) = 𝐴)
Theorem	ccats1pfxeqbi 40294	A word is a prefix of a word with length greater by 1 than the first word iff the second word is the first word concatenated with the last symbol of the second word. Could replace ccats1swrdeqbi 13349. (Contributed by AV, 10-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑈 ∈ Word 𝑉 ∧ (#‘𝑈) = ((#‘𝑊) + 1)) → (𝑊 = (𝑈 prefix (#‘𝑊)) ↔ 𝑈 = (𝑊 ++ ⟨“( lastS ‘𝑈)”⟩)))
Theorem	pfxccatin12d 40295	The subword of a concatenation of two words within both of the concatenated words. Could replace swrdccatin12d 13352. (Contributed by AV, 10-May-2020.)
⊢ (𝜑 → (#‘𝐴) = 𝐿)    &   ⊢ (𝜑 → (𝐴 ∈ Word 𝑉 ∧ 𝐵 ∈ Word 𝑉))    &   ⊢ (𝜑 → 𝑀 ∈ (0...𝐿))    &   ⊢ (𝜑 → 𝑁 ∈ (𝐿...(𝐿 + (#‘𝐵))))    ⇒   ⊢ (𝜑 → ((𝐴 ++ 𝐵) substr ⟨𝑀, 𝑁⟩) = ((𝐴 substr ⟨𝑀, 𝐿⟩) ++ (𝐵 prefix (𝑁 − 𝐿))))
Theorem	reuccatpfxs1lem 40296*	Lemma for reuccatpfxs1 40297. Could replace reuccats1lem 13331. (Contributed by AV, 9-May-2020.)
⊢ (((𝑊 ∈ Word 𝑉 ∧ 𝑈 ∈ 𝑋) ∧ ∀𝑠 ∈ 𝑉 ((𝑊 ++ ⟨“𝑠”⟩) ∈ 𝑋 → 𝑆 = 𝑠) ∧ ∀𝑥 ∈ 𝑋 (𝑥 ∈ Word 𝑉 ∧ (#‘𝑥) = ((#‘𝑊) + 1))) → (𝑊 = (𝑈 prefix (#‘𝑊)) → 𝑈 = (𝑊 ++ ⟨“𝑆”⟩)))
Theorem	reuccatpfxs1 40297*	There is a unique word having the length of a given word increased by 1 with the given word as prefix if there is a unique symbol which extends the given word. Could replace reuccats1 13332. (Contributed by AV, 10-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ ∀𝑥 ∈ 𝑋 (𝑥 ∈ Word 𝑉 ∧ (#‘𝑥) = ((#‘𝑊) + 1))) → (∃!𝑣 ∈ 𝑉 (𝑊 ++ ⟨“𝑣”⟩) ∈ 𝑋 → ∃!𝑤 ∈ 𝑋 𝑊 = (𝑤 prefix (#‘𝑊))))
Theorem	splvalpfx 40298	Value of the substring replacement operator. (Contributed by AV, 11-May-2020.)
⊢ ((𝑆 ∈ 𝑉 ∧ (𝐹 ∈ ℕ0 ∧ 𝑇 ∈ 𝑋 ∧ 𝑅 ∈ 𝑌)) → (𝑆 splice ⟨𝐹, 𝑇, 𝑅⟩) = (((𝑆 prefix 𝐹) ++ 𝑅) ++ (𝑆 substr ⟨𝑇, (#‘𝑆)⟩)))
Theorem	repswpfx 40299	A prefix of a repeated symbol word is a repeated symbol word. (Contributed by AV, 11-May-2020.)
⊢ ((𝑆 ∈ 𝑉 ∧ 𝑁 ∈ ℕ0 ∧ 𝐿 ∈ (0...𝑁)) → ((𝑆 repeatS 𝑁) prefix 𝐿) = (𝑆 repeatS 𝐿))
Theorem	cshword2 40300	Perform a cyclical shift for a word. (Contributed by AV, 11-May-2020.)
⊢ ((𝑊 ∈ Word 𝑉 ∧ 𝑁 ∈ ℤ) → (𝑊 cyclShift 𝑁) = ((𝑊 substr ⟨(𝑁 mod (#‘𝑊)), (#‘𝑊)⟩) ++ (𝑊 prefix (𝑁 mod (#‘𝑊)))))