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| Type | Label | Description |
|---|---|---|
| Statement | ||
| Theorem | cygth 21501* | The "fundamental theorem of cyclic groups". Cyclic groups are exactly the additive groups ℤ / 𝑛ℤ, for 0 ≤ 𝑛 (where 𝑛 = 0 is the infinite cyclic group ℤ), up to isomorphism. (Contributed by Mario Carneiro, 21-Apr-2016.) |
| ⊢ (𝐺 ∈ CycGrp ↔ ∃𝑛 ∈ ℕ0 𝐺 ≃𝑔 (ℤ/nℤ‘𝑛)) | ||
| Theorem | cyggic 21502 | Cyclic groups are isomorphic precisely when they have the same order. (Contributed by Mario Carneiro, 21-Apr-2016.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ 𝐶 = (Base‘𝐻) ⇒ ⊢ ((𝐺 ∈ CycGrp ∧ 𝐻 ∈ CycGrp) → (𝐺 ≃𝑔 𝐻 ↔ 𝐵 ≈ 𝐶)) | ||
| Theorem | frgpcyg 21503 | A free group is cyclic iff it has zero or one generator. (Contributed by Mario Carneiro, 21-Apr-2016.) (Proof shortened by AV, 18-Apr-2021.) |
| ⊢ 𝐺 = (freeGrp‘𝐼) ⇒ ⊢ (𝐼 ≼ 1o ↔ 𝐺 ∈ CycGrp) | ||
| Theorem | freshmansdream 21504 | For a prime number 𝑃, if 𝑋 and 𝑌 are members of a commutative ring 𝑅 of characteristic 𝑃, then ((𝑋 + 𝑌)↑𝑃) = ((𝑋↑𝑃) + (𝑌↑𝑃)). This theorem is sometimes referred to as "the freshman's dream" . (Contributed by Thierry Arnoux, 18-Sep-2023.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ + = (+g‘𝑅) & ⊢ ↑ = (.g‘(mulGrp‘𝑅)) & ⊢ 𝑃 = (chr‘𝑅) & ⊢ (𝜑 → 𝑅 ∈ CRing) & ⊢ (𝜑 → 𝑃 ∈ ℙ) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐵) ⇒ ⊢ (𝜑 → (𝑃 ↑ (𝑋 + 𝑌)) = ((𝑃 ↑ 𝑋) + (𝑃 ↑ 𝑌))) | ||
| Theorem | frobrhm 21505* | In a commutative ring with prime characteristic, the Frobenius function 𝐹 is a ring endomorphism, thus named the Frobenius endomorphism. (Contributed by Thierry Arnoux, 31-May-2024.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ 𝑃 = (chr‘𝑅) & ⊢ ↑ = (.g‘(mulGrp‘𝑅)) & ⊢ 𝐹 = (𝑥 ∈ 𝐵 ↦ (𝑃 ↑ 𝑥)) & ⊢ (𝜑 → 𝑅 ∈ CRing) & ⊢ (𝜑 → 𝑃 ∈ ℙ) ⇒ ⊢ (𝜑 → 𝐹 ∈ (𝑅 RingHom 𝑅)) | ||
| Theorem | ofldchr 21506 | The characteristic of an ordered field is zero. (Contributed by Thierry Arnoux, 21-Jan-2018.) (Proof shortened by AV, 6-Oct-2020.) |
| ⊢ (𝐹 ∈ oField → (chr‘𝐹) = 0) | ||
| Theorem | cnmsgnsubg 21507 | The signs form a multiplicative subgroup of the complex numbers. (Contributed by Stefan O'Rear, 28-Aug-2015.) |
| ⊢ 𝑀 = ((mulGrp‘ℂfld) ↾s (ℂ ∖ {0})) ⇒ ⊢ {1, -1} ∈ (SubGrp‘𝑀) | ||
| Theorem | cnmsgnbas 21508 | The base set of the sign subgroup of the complex numbers. (Contributed by Stefan O'Rear, 28-Aug-2015.) |
| ⊢ 𝑈 = ((mulGrp‘ℂfld) ↾s {1, -1}) ⇒ ⊢ {1, -1} = (Base‘𝑈) | ||
| Theorem | cnmsgngrp 21509 | The group of signs under multiplication. (Contributed by Stefan O'Rear, 28-Aug-2015.) |
| ⊢ 𝑈 = ((mulGrp‘ℂfld) ↾s {1, -1}) ⇒ ⊢ 𝑈 ∈ Grp | ||
| Theorem | psgnghm 21510 | The sign is a homomorphism from the finitary permutation group to the numeric signs. (Contributed by Stefan O'Rear, 28-Aug-2015.) |
| ⊢ 𝑆 = (SymGrp‘𝐷) & ⊢ 𝑁 = (pmSgn‘𝐷) & ⊢ 𝐹 = (𝑆 ↾s dom 𝑁) & ⊢ 𝑈 = ((mulGrp‘ℂfld) ↾s {1, -1}) ⇒ ⊢ (𝐷 ∈ 𝑉 → 𝑁 ∈ (𝐹 GrpHom 𝑈)) | ||
| Theorem | psgnghm2 21511 | The sign is a homomorphism from the finite symmetric group to the numeric signs. (Contributed by Stefan O'Rear, 28-Aug-2015.) |
| ⊢ 𝑆 = (SymGrp‘𝐷) & ⊢ 𝑁 = (pmSgn‘𝐷) & ⊢ 𝑈 = ((mulGrp‘ℂfld) ↾s {1, -1}) ⇒ ⊢ (𝐷 ∈ Fin → 𝑁 ∈ (𝑆 GrpHom 𝑈)) | ||
| Theorem | psgninv 21512 | The sign of a permutation equals the sign of the inverse of the permutation. (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑆 = (SymGrp‘𝐷) & ⊢ 𝑁 = (pmSgn‘𝐷) & ⊢ 𝑃 = (Base‘𝑆) ⇒ ⊢ ((𝐷 ∈ Fin ∧ 𝐹 ∈ 𝑃) → (𝑁‘◡𝐹) = (𝑁‘𝐹)) | ||
| Theorem | psgnco 21513 | Multiplicativity of the permutation sign function. (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑆 = (SymGrp‘𝐷) & ⊢ 𝑁 = (pmSgn‘𝐷) & ⊢ 𝑃 = (Base‘𝑆) ⇒ ⊢ ((𝐷 ∈ Fin ∧ 𝐹 ∈ 𝑃 ∧ 𝐺 ∈ 𝑃) → (𝑁‘(𝐹 ∘ 𝐺)) = ((𝑁‘𝐹) · (𝑁‘𝐺))) | ||
| Theorem | zrhpsgnmhm 21514 | Embedding of permutation signs into an arbitrary ring is a homomorphism. (Contributed by SO, 9-Jul-2018.) |
| ⊢ ((𝑅 ∈ Ring ∧ 𝐴 ∈ Fin) → ((ℤRHom‘𝑅) ∘ (pmSgn‘𝐴)) ∈ ((SymGrp‘𝐴) MndHom (mulGrp‘𝑅))) | ||
| Theorem | zrhpsgninv 21515 | The embedded sign of a permutation equals the embedded sign of the inverse of the permutation. (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑃 = (Base‘(SymGrp‘𝑁)) & ⊢ 𝑌 = (ℤRHom‘𝑅) & ⊢ 𝑆 = (pmSgn‘𝑁) ⇒ ⊢ ((𝑅 ∈ Ring ∧ 𝑁 ∈ Fin ∧ 𝐹 ∈ 𝑃) → ((𝑌 ∘ 𝑆)‘◡𝐹) = ((𝑌 ∘ 𝑆)‘𝐹)) | ||
| Theorem | evpmss 21516 | Even permutations are permutations. (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑆 = (SymGrp‘𝐷) & ⊢ 𝑃 = (Base‘𝑆) ⇒ ⊢ (pmEven‘𝐷) ⊆ 𝑃 | ||
| Theorem | psgnevpmb 21517 | A class is an even permutation if it is a permutation with sign 1. (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑆 = (SymGrp‘𝐷) & ⊢ 𝑃 = (Base‘𝑆) & ⊢ 𝑁 = (pmSgn‘𝐷) ⇒ ⊢ (𝐷 ∈ Fin → (𝐹 ∈ (pmEven‘𝐷) ↔ (𝐹 ∈ 𝑃 ∧ (𝑁‘𝐹) = 1))) | ||
| Theorem | psgnodpm 21518 | A permutation which is odd (i.e. not even) has sign -1. (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑆 = (SymGrp‘𝐷) & ⊢ 𝑃 = (Base‘𝑆) & ⊢ 𝑁 = (pmSgn‘𝐷) ⇒ ⊢ ((𝐷 ∈ Fin ∧ 𝐹 ∈ (𝑃 ∖ (pmEven‘𝐷))) → (𝑁‘𝐹) = -1) | ||
| Theorem | psgnevpm 21519 | A permutation which is even has sign 1. (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑆 = (SymGrp‘𝐷) & ⊢ 𝑃 = (Base‘𝑆) & ⊢ 𝑁 = (pmSgn‘𝐷) ⇒ ⊢ ((𝐷 ∈ Fin ∧ 𝐹 ∈ (pmEven‘𝐷)) → (𝑁‘𝐹) = 1) | ||
| Theorem | psgnodpmr 21520 | If a permutation has sign -1 it is odd (not even). (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑆 = (SymGrp‘𝐷) & ⊢ 𝑃 = (Base‘𝑆) & ⊢ 𝑁 = (pmSgn‘𝐷) ⇒ ⊢ ((𝐷 ∈ Fin ∧ 𝐹 ∈ 𝑃 ∧ (𝑁‘𝐹) = -1) → 𝐹 ∈ (𝑃 ∖ (pmEven‘𝐷))) | ||
| Theorem | zrhpsgnevpm 21521 | The sign of an even permutation embedded into a ring is the unity element of the ring. (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑌 = (ℤRHom‘𝑅) & ⊢ 𝑆 = (pmSgn‘𝑁) & ⊢ 1 = (1r‘𝑅) ⇒ ⊢ ((𝑅 ∈ Ring ∧ 𝑁 ∈ Fin ∧ 𝐹 ∈ (pmEven‘𝑁)) → ((𝑌 ∘ 𝑆)‘𝐹) = 1 ) | ||
| Theorem | zrhpsgnodpm 21522 | The sign of an odd permutation embedded into a ring is the additive inverse of the unity element of the ring. (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑌 = (ℤRHom‘𝑅) & ⊢ 𝑆 = (pmSgn‘𝑁) & ⊢ 1 = (1r‘𝑅) & ⊢ 𝑃 = (Base‘(SymGrp‘𝑁)) & ⊢ 𝐼 = (invg‘𝑅) ⇒ ⊢ ((𝑅 ∈ Ring ∧ 𝑁 ∈ Fin ∧ 𝐹 ∈ (𝑃 ∖ (pmEven‘𝑁))) → ((𝑌 ∘ 𝑆)‘𝐹) = (𝐼‘ 1 )) | ||
| Theorem | cofipsgn 21523 | Composition of any class 𝑌 and the sign function for a finite permutation. (Contributed by AV, 27-Dec-2018.) (Revised by AV, 3-Jul-2022.) |
| ⊢ 𝑃 = (Base‘(SymGrp‘𝑁)) & ⊢ 𝑆 = (pmSgn‘𝑁) ⇒ ⊢ ((𝑁 ∈ Fin ∧ 𝑄 ∈ 𝑃) → ((𝑌 ∘ 𝑆)‘𝑄) = (𝑌‘(𝑆‘𝑄))) | ||
| Theorem | zrhpsgnelbas 21524 | Embedding of permutation signs into a ring results in an element of the ring. (Contributed by AV, 1-Jan-2019.) |
| ⊢ 𝑃 = (Base‘(SymGrp‘𝑁)) & ⊢ 𝑆 = (pmSgn‘𝑁) & ⊢ 𝑌 = (ℤRHom‘𝑅) ⇒ ⊢ ((𝑅 ∈ Ring ∧ 𝑁 ∈ Fin ∧ 𝑄 ∈ 𝑃) → (𝑌‘(𝑆‘𝑄)) ∈ (Base‘𝑅)) | ||
| Theorem | zrhcopsgnelbas 21525 | Embedding of permutation signs into a ring results in an element of the ring. (Contributed by AV, 1-Jan-2019.) (Proof shortened by AV, 3-Jul-2022.) |
| ⊢ 𝑃 = (Base‘(SymGrp‘𝑁)) & ⊢ 𝑆 = (pmSgn‘𝑁) & ⊢ 𝑌 = (ℤRHom‘𝑅) ⇒ ⊢ ((𝑅 ∈ Ring ∧ 𝑁 ∈ Fin ∧ 𝑄 ∈ 𝑃) → ((𝑌 ∘ 𝑆)‘𝑄) ∈ (Base‘𝑅)) | ||
| Theorem | evpmodpmf1o 21526* | The function for performing an even permutation after a fixed odd permutation is one to one onto all odd permutations. (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑆 = (SymGrp‘𝐷) & ⊢ 𝑃 = (Base‘𝑆) ⇒ ⊢ ((𝐷 ∈ Fin ∧ 𝐹 ∈ (𝑃 ∖ (pmEven‘𝐷))) → (𝑓 ∈ (pmEven‘𝐷) ↦ (𝐹(+g‘𝑆)𝑓)):(pmEven‘𝐷)–1-1-onto→(𝑃 ∖ (pmEven‘𝐷))) | ||
| Theorem | pmtrodpm 21527 | A transposition is an odd permutation. (Contributed by SO, 9-Jul-2018.) |
| ⊢ 𝑆 = (SymGrp‘𝐷) & ⊢ 𝑃 = (Base‘𝑆) & ⊢ 𝑇 = ran (pmTrsp‘𝐷) ⇒ ⊢ ((𝐷 ∈ Fin ∧ 𝐹 ∈ 𝑇) → 𝐹 ∈ (𝑃 ∖ (pmEven‘𝐷))) | ||
| Theorem | psgnfix1 21528* | A permutation of a finite set fixing one element is generated by transpositions not involving the fixed element. (Contributed by AV, 13-Jan-2019.) |
| ⊢ 𝑃 = (Base‘(SymGrp‘𝑁)) & ⊢ 𝑇 = ran (pmTrsp‘(𝑁 ∖ {𝐾})) & ⊢ 𝑆 = (SymGrp‘(𝑁 ∖ {𝐾})) ⇒ ⊢ ((𝑁 ∈ Fin ∧ 𝐾 ∈ 𝑁) → (𝑄 ∈ {𝑞 ∈ 𝑃 ∣ (𝑞‘𝐾) = 𝐾} → ∃𝑤 ∈ Word 𝑇(𝑄 ↾ (𝑁 ∖ {𝐾})) = (𝑆 Σg 𝑤))) | ||
| Theorem | psgnfix2 21529* | A permutation of a finite set fixing one element is generated by transpositions not involving the fixed element. (Contributed by AV, 17-Jan-2019.) |
| ⊢ 𝑃 = (Base‘(SymGrp‘𝑁)) & ⊢ 𝑇 = ran (pmTrsp‘(𝑁 ∖ {𝐾})) & ⊢ 𝑆 = (SymGrp‘(𝑁 ∖ {𝐾})) & ⊢ 𝑍 = (SymGrp‘𝑁) & ⊢ 𝑅 = ran (pmTrsp‘𝑁) ⇒ ⊢ ((𝑁 ∈ Fin ∧ 𝐾 ∈ 𝑁) → (𝑄 ∈ {𝑞 ∈ 𝑃 ∣ (𝑞‘𝐾) = 𝐾} → ∃𝑤 ∈ Word 𝑅𝑄 = (𝑍 Σg 𝑤))) | ||
| Theorem | psgndiflemB 21530* | Lemma 1 for psgndif 21532. (Contributed by AV, 27-Jan-2019.) |
| ⊢ 𝑃 = (Base‘(SymGrp‘𝑁)) & ⊢ 𝑇 = ran (pmTrsp‘(𝑁 ∖ {𝐾})) & ⊢ 𝑆 = (SymGrp‘(𝑁 ∖ {𝐾})) & ⊢ 𝑍 = (SymGrp‘𝑁) & ⊢ 𝑅 = ran (pmTrsp‘𝑁) ⇒ ⊢ (((𝑁 ∈ Fin ∧ 𝐾 ∈ 𝑁) ∧ 𝑄 ∈ {𝑞 ∈ 𝑃 ∣ (𝑞‘𝐾) = 𝐾}) → ((𝑊 ∈ Word 𝑇 ∧ (𝑄 ↾ (𝑁 ∖ {𝐾})) = (𝑆 Σg 𝑊)) → ((𝑈 ∈ Word 𝑅 ∧ (♯‘𝑊) = (♯‘𝑈) ∧ ∀𝑖 ∈ (0..^(♯‘𝑊))(((𝑈‘𝑖)‘𝐾) = 𝐾 ∧ ∀𝑛 ∈ (𝑁 ∖ {𝐾})((𝑊‘𝑖)‘𝑛) = ((𝑈‘𝑖)‘𝑛))) → 𝑄 = (𝑍 Σg 𝑈)))) | ||
| Theorem | psgndiflemA 21531* | Lemma 2 for psgndif 21532. (Contributed by AV, 31-Jan-2019.) |
| ⊢ 𝑃 = (Base‘(SymGrp‘𝑁)) & ⊢ 𝑇 = ran (pmTrsp‘(𝑁 ∖ {𝐾})) & ⊢ 𝑆 = (SymGrp‘(𝑁 ∖ {𝐾})) & ⊢ 𝑍 = (SymGrp‘𝑁) & ⊢ 𝑅 = ran (pmTrsp‘𝑁) ⇒ ⊢ (((𝑁 ∈ Fin ∧ 𝐾 ∈ 𝑁) ∧ 𝑄 ∈ {𝑞 ∈ 𝑃 ∣ (𝑞‘𝐾) = 𝐾}) → ((𝑊 ∈ Word 𝑇 ∧ (𝑄 ↾ (𝑁 ∖ {𝐾})) = (𝑆 Σg 𝑊) ∧ 𝑈 ∈ Word 𝑅) → (𝑄 = ((SymGrp‘𝑁) Σg 𝑈) → (-1↑(♯‘𝑊)) = (-1↑(♯‘𝑈))))) | ||
| Theorem | psgndif 21532* | Embedding of permutation signs restricted to a set without a single element into a ring. (Contributed by AV, 31-Jan-2019.) |
| ⊢ 𝑃 = (Base‘(SymGrp‘𝑁)) & ⊢ 𝑆 = (pmSgn‘𝑁) & ⊢ 𝑍 = (pmSgn‘(𝑁 ∖ {𝐾})) ⇒ ⊢ ((𝑁 ∈ Fin ∧ 𝐾 ∈ 𝑁) → (𝑄 ∈ {𝑞 ∈ 𝑃 ∣ (𝑞‘𝐾) = 𝐾} → (𝑍‘(𝑄 ↾ (𝑁 ∖ {𝐾}))) = (𝑆‘𝑄))) | ||
| Theorem | copsgndif 21533* | Embedding of permutation signs restricted to a set without a single element into a ring. (Contributed by AV, 31-Jan-2019.) (Revised by AV, 5-Jul-2022.) |
| ⊢ 𝑃 = (Base‘(SymGrp‘𝑁)) & ⊢ 𝑆 = (pmSgn‘𝑁) & ⊢ 𝑍 = (pmSgn‘(𝑁 ∖ {𝐾})) ⇒ ⊢ ((𝑁 ∈ Fin ∧ 𝐾 ∈ 𝑁) → (𝑄 ∈ {𝑞 ∈ 𝑃 ∣ (𝑞‘𝐾) = 𝐾} → ((𝑌 ∘ 𝑍)‘(𝑄 ↾ (𝑁 ∖ {𝐾}))) = ((𝑌 ∘ 𝑆)‘𝑄))) | ||
| Syntax | crefld 21534 | Extend class notation with the field of real numbers. |
| class ℝfld | ||
| Definition | df-refld 21535 | The field of real numbers. (Contributed by Thierry Arnoux, 30-Jun-2019.) |
| ⊢ ℝfld = (ℂfld ↾s ℝ) | ||
| Theorem | rebase 21536 | The base of the field of reals. (Contributed by Thierry Arnoux, 1-Nov-2017.) |
| ⊢ ℝ = (Base‘ℝfld) | ||
| Theorem | remulg 21537 | The multiplication (group power) operation of the group of reals. (Contributed by Thierry Arnoux, 1-Nov-2017.) |
| ⊢ ((𝑁 ∈ ℤ ∧ 𝐴 ∈ ℝ) → (𝑁(.g‘ℝfld)𝐴) = (𝑁 · 𝐴)) | ||
| Theorem | resubdrg 21538 | The real numbers form a division subring of the complex numbers. (Contributed by Mario Carneiro, 4-Dec-2014.) (Revised by Thierry Arnoux, 30-Jun-2019.) |
| ⊢ (ℝ ∈ (SubRing‘ℂfld) ∧ ℝfld ∈ DivRing) | ||
| Theorem | resubgval 21539 | Subtraction in the field of real numbers. (Contributed by Thierry Arnoux, 30-Jun-2019.) |
| ⊢ − = (-g‘ℝfld) ⇒ ⊢ ((𝑋 ∈ ℝ ∧ 𝑌 ∈ ℝ) → (𝑋 − 𝑌) = (𝑋 − 𝑌)) | ||
| Theorem | replusg 21540 | The addition operation of the field of reals. (Contributed by Thierry Arnoux, 21-Jan-2018.) |
| ⊢ + = (+g‘ℝfld) | ||
| Theorem | remulr 21541 | The multiplication operation of the field of reals. (Contributed by Thierry Arnoux, 1-Nov-2017.) |
| ⊢ · = (.r‘ℝfld) | ||
| Theorem | re0g 21542 | The zero element of the field of reals. (Contributed by Thierry Arnoux, 1-Nov-2017.) |
| ⊢ 0 = (0g‘ℝfld) | ||
| Theorem | re1r 21543 | The unity element of the field of reals. (Contributed by Thierry Arnoux, 1-Nov-2017.) |
| ⊢ 1 = (1r‘ℝfld) | ||
| Theorem | rele2 21544 | The ordering relation of the field of reals. (Contributed by Thierry Arnoux, 21-Jan-2018.) |
| ⊢ ≤ = (le‘ℝfld) | ||
| Theorem | relt 21545 | The ordering relation of the field of reals. (Contributed by Thierry Arnoux, 21-Jan-2018.) |
| ⊢ < = (lt‘ℝfld) | ||
| Theorem | reds 21546 | The distance of the field of reals. (Contributed by Thierry Arnoux, 20-Jun-2019.) |
| ⊢ (abs ∘ − ) = (dist‘ℝfld) | ||
| Theorem | redvr 21547 | The division operation of the field of reals. (Contributed by Thierry Arnoux, 1-Nov-2017.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐵 ≠ 0) → (𝐴(/r‘ℝfld)𝐵) = (𝐴 / 𝐵)) | ||
| Theorem | retos 21548 | The real numbers are a totally ordered set. (Contributed by Thierry Arnoux, 21-Jan-2018.) |
| ⊢ ℝfld ∈ Toset | ||
| Theorem | refld 21549 | The real numbers form a field. (Contributed by Thierry Arnoux, 1-Nov-2017.) |
| ⊢ ℝfld ∈ Field | ||
| Theorem | refldcj 21550 | The conjugation operation of the field of real numbers. (Contributed by Thierry Arnoux, 30-Jun-2019.) |
| ⊢ ∗ = (*𝑟‘ℝfld) | ||
| Theorem | resrng 21551 | The real numbers form a star ring. (Contributed by Thierry Arnoux, 19-Apr-2019.) (Proof shortened by Thierry Arnoux, 11-Jan-2025.) |
| ⊢ ℝfld ∈ *-Ring | ||
| Theorem | regsumsupp 21552* | The group sum over the real numbers, expressed as a finite sum. (Contributed by Thierry Arnoux, 22-Jun-2019.) (Proof shortened by AV, 19-Jul-2019.) |
| ⊢ ((𝐹:𝐼⟶ℝ ∧ 𝐹 finSupp 0 ∧ 𝐼 ∈ 𝑉) → (ℝfld Σg 𝐹) = Σ𝑥 ∈ (𝐹 supp 0)(𝐹‘𝑥)) | ||
| Theorem | rzgrp 21553 | The quotient group ℝ / ℤ is a group. (Contributed by Thierry Arnoux, 26-Jan-2020.) |
| ⊢ 𝑅 = (ℝfld /s (ℝfld ~QG ℤ)) ⇒ ⊢ 𝑅 ∈ Grp | ||
| Syntax | cphl 21554 | Extend class notation with class of all pre-Hilbert spaces. |
| class PreHil | ||
| Syntax | cipf 21555 | Extend class notation with inner product function. |
| class ·if | ||
| Definition | df-phl 21556* | Define the class of all pre-Hilbert spaces (inner product spaces) over arbitrary fields with involution. (Some textbook definitions are more restrictive and require the field of scalars to be the field of real or complex numbers). (Contributed by NM, 22-Sep-2011.) |
| ⊢ PreHil = {𝑔 ∈ LVec ∣ [(Base‘𝑔) / 𝑣][(·𝑖‘𝑔) / ℎ][(Scalar‘𝑔) / 𝑓](𝑓 ∈ *-Ring ∧ ∀𝑥 ∈ 𝑣 ((𝑦 ∈ 𝑣 ↦ (𝑦ℎ𝑥)) ∈ (𝑔 LMHom (ringLMod‘𝑓)) ∧ ((𝑥ℎ𝑥) = (0g‘𝑓) → 𝑥 = (0g‘𝑔)) ∧ ∀𝑦 ∈ 𝑣 ((*𝑟‘𝑓)‘(𝑥ℎ𝑦)) = (𝑦ℎ𝑥)))} | ||
| Definition | df-ipf 21557* | Define the inner product function. Usually we will use ·𝑖 directly instead of ·if, and they have the same behavior in most cases. The main advantage of ·if is that it is a guaranteed function (ipffn 21581), while ·𝑖 only has closure (ipcl 21563). (Contributed by Mario Carneiro, 12-Aug-2015.) |
| ⊢ ·if = (𝑔 ∈ V ↦ (𝑥 ∈ (Base‘𝑔), 𝑦 ∈ (Base‘𝑔) ↦ (𝑥(·𝑖‘𝑔)𝑦))) | ||
| Theorem | isphl 21558* | The predicate "is a generalized pre-Hilbert (inner product) space". (Contributed by NM, 22-Sep-2011.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝑉 = (Base‘𝑊) & ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 0 = (0g‘𝑊) & ⊢ ∗ = (*𝑟‘𝐹) & ⊢ 𝑍 = (0g‘𝐹) ⇒ ⊢ (𝑊 ∈ PreHil ↔ (𝑊 ∈ LVec ∧ 𝐹 ∈ *-Ring ∧ ∀𝑥 ∈ 𝑉 ((𝑦 ∈ 𝑉 ↦ (𝑦 , 𝑥)) ∈ (𝑊 LMHom (ringLMod‘𝐹)) ∧ ((𝑥 , 𝑥) = 𝑍 → 𝑥 = 0 ) ∧ ∀𝑦 ∈ 𝑉 ( ∗ ‘(𝑥 , 𝑦)) = (𝑦 , 𝑥)))) | ||
| Theorem | phllvec 21559 | A pre-Hilbert space is a left vector space. (Contributed by Mario Carneiro, 7-Oct-2015.) |
| ⊢ (𝑊 ∈ PreHil → 𝑊 ∈ LVec) | ||
| Theorem | phllmod 21560 | A pre-Hilbert space is a left module. (Contributed by Mario Carneiro, 7-Oct-2015.) |
| ⊢ (𝑊 ∈ PreHil → 𝑊 ∈ LMod) | ||
| Theorem | phlsrng 21561 | The scalar ring of a pre-Hilbert space is a star ring. (Contributed by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) ⇒ ⊢ (𝑊 ∈ PreHil → 𝐹 ∈ *-Ring) | ||
| Theorem | phllmhm 21562* | The inner product of a pre-Hilbert space is linear in its left argument. (Contributed by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ 𝐺 = (𝑥 ∈ 𝑉 ↦ (𝑥 , 𝐴)) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ 𝐴 ∈ 𝑉) → 𝐺 ∈ (𝑊 LMHom (ringLMod‘𝐹))) | ||
| Theorem | ipcl 21563 | Closure of the inner product operation in a pre-Hilbert space. (Contributed by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ 𝐾 = (Base‘𝐹) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉) → (𝐴 , 𝐵) ∈ 𝐾) | ||
| Theorem | ipcj 21564 | Conjugate of an inner product in a pre-Hilbert space. Equation I1 of [Ponnusamy] p. 362. (Contributed by NM, 1-Feb-2007.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ ∗ = (*𝑟‘𝐹) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉) → ( ∗ ‘(𝐴 , 𝐵)) = (𝐵 , 𝐴)) | ||
| Theorem | iporthcom 21565 | Orthogonality (meaning inner product is 0) is commutative. (Contributed by NM, 17-Apr-2008.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ 𝑍 = (0g‘𝐹) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉) → ((𝐴 , 𝐵) = 𝑍 ↔ (𝐵 , 𝐴) = 𝑍)) | ||
| Theorem | ip0l 21566 | Inner product with a zero first argument. Part of proof of Theorem 6.44 of [Ponnusamy] p. 361. (Contributed by NM, 5-Feb-2007.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ 𝑍 = (0g‘𝐹) & ⊢ 0 = (0g‘𝑊) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ 𝐴 ∈ 𝑉) → ( 0 , 𝐴) = 𝑍) | ||
| Theorem | ip0r 21567 | Inner product with a zero second argument. (Contributed by NM, 5-Feb-2007.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ 𝑍 = (0g‘𝐹) & ⊢ 0 = (0g‘𝑊) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ 𝐴 ∈ 𝑉) → (𝐴 , 0 ) = 𝑍) | ||
| Theorem | ipeq0 21568 | The inner product of a vector with itself is zero iff the vector is zero. Part of Definition 3.1-1 of [Kreyszig] p. 129. (Contributed by NM, 24-Jan-2008.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ 𝑍 = (0g‘𝐹) & ⊢ 0 = (0g‘𝑊) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ 𝐴 ∈ 𝑉) → ((𝐴 , 𝐴) = 𝑍 ↔ 𝐴 = 0 )) | ||
| Theorem | ipdir 21569 | Distributive law for inner product (right-distributivity). Equation I3 of [Ponnusamy] p. 362. (Contributed by NM, 25-Aug-2007.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ + = (+g‘𝑊) & ⊢ ⨣ = (+g‘𝐹) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ (𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ∧ 𝐶 ∈ 𝑉)) → ((𝐴 + 𝐵) , 𝐶) = ((𝐴 , 𝐶) ⨣ (𝐵 , 𝐶))) | ||
| Theorem | ipdi 21570 | Distributive law for inner product (left-distributivity). (Contributed by NM, 20-Nov-2007.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ + = (+g‘𝑊) & ⊢ ⨣ = (+g‘𝐹) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ (𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ∧ 𝐶 ∈ 𝑉)) → (𝐴 , (𝐵 + 𝐶)) = ((𝐴 , 𝐵) ⨣ (𝐴 , 𝐶))) | ||
| Theorem | ip2di 21571 | Distributive law for inner product. (Contributed by NM, 17-Apr-2008.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ + = (+g‘𝑊) & ⊢ ⨣ = (+g‘𝐹) & ⊢ (𝜑 → 𝑊 ∈ PreHil) & ⊢ (𝜑 → 𝐴 ∈ 𝑉) & ⊢ (𝜑 → 𝐵 ∈ 𝑉) & ⊢ (𝜑 → 𝐶 ∈ 𝑉) & ⊢ (𝜑 → 𝐷 ∈ 𝑉) ⇒ ⊢ (𝜑 → ((𝐴 + 𝐵) , (𝐶 + 𝐷)) = (((𝐴 , 𝐶) ⨣ (𝐵 , 𝐷)) ⨣ ((𝐴 , 𝐷) ⨣ (𝐵 , 𝐶)))) | ||
| Theorem | ipsubdir 21572 | Distributive law for inner product subtraction. (Contributed by NM, 20-Nov-2007.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ − = (-g‘𝑊) & ⊢ 𝑆 = (-g‘𝐹) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ (𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ∧ 𝐶 ∈ 𝑉)) → ((𝐴 − 𝐵) , 𝐶) = ((𝐴 , 𝐶)𝑆(𝐵 , 𝐶))) | ||
| Theorem | ipsubdi 21573 | Distributive law for inner product subtraction. (Contributed by NM, 20-Nov-2007.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ − = (-g‘𝑊) & ⊢ 𝑆 = (-g‘𝐹) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ (𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ∧ 𝐶 ∈ 𝑉)) → (𝐴 , (𝐵 − 𝐶)) = ((𝐴 , 𝐵)𝑆(𝐴 , 𝐶))) | ||
| Theorem | ip2subdi 21574 | Distributive law for inner product subtraction. (Contributed by Mario Carneiro, 8-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ − = (-g‘𝑊) & ⊢ 𝑆 = (-g‘𝐹) & ⊢ + = (+g‘𝐹) & ⊢ (𝜑 → 𝑊 ∈ PreHil) & ⊢ (𝜑 → 𝐴 ∈ 𝑉) & ⊢ (𝜑 → 𝐵 ∈ 𝑉) & ⊢ (𝜑 → 𝐶 ∈ 𝑉) & ⊢ (𝜑 → 𝐷 ∈ 𝑉) ⇒ ⊢ (𝜑 → ((𝐴 − 𝐵) , (𝐶 − 𝐷)) = (((𝐴 , 𝐶) + (𝐵 , 𝐷))𝑆((𝐴 , 𝐷) + (𝐵 , 𝐶)))) | ||
| Theorem | ipass 21575 | Associative law for inner product. Equation I2 of [Ponnusamy] p. 363. (Contributed by NM, 25-Aug-2007.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ 𝐾 = (Base‘𝐹) & ⊢ · = ( ·𝑠 ‘𝑊) & ⊢ × = (.r‘𝐹) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ (𝐴 ∈ 𝐾 ∧ 𝐵 ∈ 𝑉 ∧ 𝐶 ∈ 𝑉)) → ((𝐴 · 𝐵) , 𝐶) = (𝐴 × (𝐵 , 𝐶))) | ||
| Theorem | ipassr 21576 | "Associative" law for second argument of inner product (compare ipass 21575). (Contributed by NM, 25-Aug-2007.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ 𝐾 = (Base‘𝐹) & ⊢ · = ( ·𝑠 ‘𝑊) & ⊢ × = (.r‘𝐹) & ⊢ ∗ = (*𝑟‘𝐹) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ (𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ∧ 𝐶 ∈ 𝐾)) → (𝐴 , (𝐶 · 𝐵)) = ((𝐴 , 𝐵) × ( ∗ ‘𝐶))) | ||
| Theorem | ipassr2 21577 | "Associative" law for inner product. Conjugate version of ipassr 21576. (Contributed by NM, 25-Aug-2007.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) & ⊢ 𝐾 = (Base‘𝐹) & ⊢ · = ( ·𝑠 ‘𝑊) & ⊢ × = (.r‘𝐹) & ⊢ ∗ = (*𝑟‘𝐹) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ (𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ∧ 𝐶 ∈ 𝐾)) → ((𝐴 , 𝐵) × 𝐶) = (𝐴 , (( ∗ ‘𝐶) · 𝐵))) | ||
| Theorem | ipffval 21578* | The inner product operation as a function. (Contributed by Mario Carneiro, 12-Oct-2015.) (Proof shortened by AV, 2-Mar-2024.) |
| ⊢ 𝑉 = (Base‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ · = (·if‘𝑊) ⇒ ⊢ · = (𝑥 ∈ 𝑉, 𝑦 ∈ 𝑉 ↦ (𝑥 , 𝑦)) | ||
| Theorem | ipfval 21579 | The inner product operation as a function. (Contributed by Mario Carneiro, 14-Aug-2015.) |
| ⊢ 𝑉 = (Base‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ · = (·if‘𝑊) ⇒ ⊢ ((𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → (𝑋 · 𝑌) = (𝑋 , 𝑌)) | ||
| Theorem | ipfeq 21580 | If the inner product operation is already a function, the functionalization of it is equal to the original operation. (Contributed by Mario Carneiro, 14-Aug-2015.) |
| ⊢ 𝑉 = (Base‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ · = (·if‘𝑊) ⇒ ⊢ ( , Fn (𝑉 × 𝑉) → · = , ) | ||
| Theorem | ipffn 21581 | The inner product operation is a function. (Contributed by Mario Carneiro, 20-Sep-2015.) |
| ⊢ 𝑉 = (Base‘𝑊) & ⊢ , = (·if‘𝑊) ⇒ ⊢ , Fn (𝑉 × 𝑉) | ||
| Theorem | phlipf 21582 | The inner product operation is a function. (Contributed by Mario Carneiro, 14-Aug-2015.) |
| ⊢ 𝑉 = (Base‘𝑊) & ⊢ , = (·if‘𝑊) & ⊢ 𝑆 = (Scalar‘𝑊) & ⊢ 𝐾 = (Base‘𝑆) ⇒ ⊢ (𝑊 ∈ PreHil → , :(𝑉 × 𝑉)⟶𝐾) | ||
| Theorem | ip2eq 21583* | Two vectors are equal iff their inner products with all other vectors are equal. (Contributed by NM, 24-Jan-2008.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑉 = (Base‘𝑊) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉) → (𝐴 = 𝐵 ↔ ∀𝑥 ∈ 𝑉 (𝑥 , 𝐴) = (𝑥 , 𝐵))) | ||
| Theorem | isphld 21584* | Properties that determine a pre-Hilbert (inner product) space. (Contributed by Mario Carneiro, 18-Nov-2013.) (Revised by Mario Carneiro, 7-Oct-2015.) |
| ⊢ (𝜑 → 𝑉 = (Base‘𝑊)) & ⊢ (𝜑 → + = (+g‘𝑊)) & ⊢ (𝜑 → · = ( ·𝑠 ‘𝑊)) & ⊢ (𝜑 → 𝐼 = (·𝑖‘𝑊)) & ⊢ (𝜑 → 0 = (0g‘𝑊)) & ⊢ (𝜑 → 𝐹 = (Scalar‘𝑊)) & ⊢ (𝜑 → 𝐾 = (Base‘𝐹)) & ⊢ (𝜑 → ⨣ = (+g‘𝐹)) & ⊢ (𝜑 → × = (.r‘𝐹)) & ⊢ (𝜑 → ∗ = (*𝑟‘𝐹)) & ⊢ (𝜑 → 𝑂 = (0g‘𝐹)) & ⊢ (𝜑 → 𝑊 ∈ LVec) & ⊢ (𝜑 → 𝐹 ∈ *-Ring) & ⊢ ((𝜑 ∧ 𝑥 ∈ 𝑉 ∧ 𝑦 ∈ 𝑉) → (𝑥𝐼𝑦) ∈ 𝐾) & ⊢ ((𝜑 ∧ 𝑞 ∈ 𝐾 ∧ (𝑥 ∈ 𝑉 ∧ 𝑦 ∈ 𝑉 ∧ 𝑧 ∈ 𝑉)) → (((𝑞 · 𝑥) + 𝑦)𝐼𝑧) = ((𝑞 × (𝑥𝐼𝑧)) ⨣ (𝑦𝐼𝑧))) & ⊢ ((𝜑 ∧ 𝑥 ∈ 𝑉 ∧ (𝑥𝐼𝑥) = 𝑂) → 𝑥 = 0 ) & ⊢ ((𝜑 ∧ 𝑥 ∈ 𝑉 ∧ 𝑦 ∈ 𝑉) → ( ∗ ‘(𝑥𝐼𝑦)) = (𝑦𝐼𝑥)) ⇒ ⊢ (𝜑 → 𝑊 ∈ PreHil) | ||
| Theorem | phlpropd 21585* | If two structures have the same components (properties), one is a pre-Hilbert space iff the other one is. (Contributed by Mario Carneiro, 8-Oct-2015.) |
| ⊢ (𝜑 → 𝐵 = (Base‘𝐾)) & ⊢ (𝜑 → 𝐵 = (Base‘𝐿)) & ⊢ ((𝜑 ∧ (𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵)) → (𝑥(+g‘𝐾)𝑦) = (𝑥(+g‘𝐿)𝑦)) & ⊢ (𝜑 → 𝐹 = (Scalar‘𝐾)) & ⊢ (𝜑 → 𝐹 = (Scalar‘𝐿)) & ⊢ 𝑃 = (Base‘𝐹) & ⊢ ((𝜑 ∧ (𝑥 ∈ 𝑃 ∧ 𝑦 ∈ 𝐵)) → (𝑥( ·𝑠 ‘𝐾)𝑦) = (𝑥( ·𝑠 ‘𝐿)𝑦)) & ⊢ ((𝜑 ∧ (𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵)) → (𝑥(·𝑖‘𝐾)𝑦) = (𝑥(·𝑖‘𝐿)𝑦)) ⇒ ⊢ (𝜑 → (𝐾 ∈ PreHil ↔ 𝐿 ∈ PreHil)) | ||
| Theorem | ssipeq 21586 | The inner product on a subspace equals the inner product on the parent space. (Contributed by AV, 19-Oct-2021.) |
| ⊢ 𝑋 = (𝑊 ↾s 𝑈) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑃 = (·𝑖‘𝑋) ⇒ ⊢ (𝑈 ∈ 𝑆 → 𝑃 = , ) | ||
| Theorem | phssipval 21587 | The inner product on a subspace in terms of the inner product on the parent space. (Contributed by NM, 28-Jan-2008.) (Revised by AV, 19-Oct-2021.) |
| ⊢ 𝑋 = (𝑊 ↾s 𝑈) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝑃 = (·𝑖‘𝑋) & ⊢ 𝑆 = (LSubSp‘𝑊) ⇒ ⊢ (((𝑊 ∈ PreHil ∧ 𝑈 ∈ 𝑆) ∧ (𝐴 ∈ 𝑈 ∧ 𝐵 ∈ 𝑈)) → (𝐴𝑃𝐵) = (𝐴 , 𝐵)) | ||
| Theorem | phssip 21588 | The inner product (as a function) on a subspace is a restriction of the inner product (as a function) on the parent space. (Contributed by NM, 28-Jan-2008.) (Revised by AV, 19-Oct-2021.) |
| ⊢ 𝑋 = (𝑊 ↾s 𝑈) & ⊢ 𝑆 = (LSubSp‘𝑊) & ⊢ · = (·if‘𝑊) & ⊢ 𝑃 = (·if‘𝑋) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ 𝑈 ∈ 𝑆) → 𝑃 = ( · ↾ (𝑈 × 𝑈))) | ||
| Theorem | phlssphl 21589 | A subspace of an inner product space (pre-Hilbert space) is an inner product space. (Contributed by AV, 25-Sep-2022.) |
| ⊢ 𝑋 = (𝑊 ↾s 𝑈) & ⊢ 𝑆 = (LSubSp‘𝑊) ⇒ ⊢ ((𝑊 ∈ PreHil ∧ 𝑈 ∈ 𝑆) → 𝑋 ∈ PreHil) | ||
| Syntax | cocv 21590 | Extend class notation with orthocomplement of a subset. |
| class ocv | ||
| Syntax | ccss 21591 | Extend class notation with set of closed subspaces. |
| class ClSubSp | ||
| Syntax | cthl 21592 | Extend class notation with the Hilbert lattice. |
| class toHL | ||
| Definition | df-ocv 21593* | Define the orthocomplement function in a given set (which usually is a pre-Hilbert space): it associates with a subset its orthogonal subset (which in the case of a closed linear subspace is its orthocomplement). (Contributed by NM, 7-Oct-2011.) |
| ⊢ ocv = (ℎ ∈ V ↦ (𝑠 ∈ 𝒫 (Base‘ℎ) ↦ {𝑥 ∈ (Base‘ℎ) ∣ ∀𝑦 ∈ 𝑠 (𝑥(·𝑖‘ℎ)𝑦) = (0g‘(Scalar‘ℎ))})) | ||
| Definition | df-css 21594* | Define the set of closed (linear) subspaces of a given pre-Hilbert space. (Contributed by NM, 7-Oct-2011.) |
| ⊢ ClSubSp = (ℎ ∈ V ↦ {𝑠 ∣ 𝑠 = ((ocv‘ℎ)‘((ocv‘ℎ)‘𝑠))}) | ||
| Definition | df-thl 21595 | Define the Hilbert lattice of closed subspaces of a given pre-Hilbert space. (Contributed by Mario Carneiro, 25-Oct-2015.) |
| ⊢ toHL = (ℎ ∈ V ↦ ((toInc‘(ClSubSp‘ℎ)) sSet 〈(oc‘ndx), (ocv‘ℎ)〉)) | ||
| Theorem | ocvfval 21596* | The orthocomplement operation. (Contributed by NM, 7-Oct-2011.) (Revised by Mario Carneiro, 13-Oct-2015.) |
| ⊢ 𝑉 = (Base‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ 0 = (0g‘𝐹) & ⊢ ⊥ = (ocv‘𝑊) ⇒ ⊢ (𝑊 ∈ 𝑋 → ⊥ = (𝑠 ∈ 𝒫 𝑉 ↦ {𝑥 ∈ 𝑉 ∣ ∀𝑦 ∈ 𝑠 (𝑥 , 𝑦) = 0 })) | ||
| Theorem | ocvval 21597* | Value of the orthocomplement of a subset (normally a subspace) of a pre-Hilbert space. (Contributed by NM, 7-Oct-2011.) (Revised by Mario Carneiro, 13-Oct-2015.) |
| ⊢ 𝑉 = (Base‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ 0 = (0g‘𝐹) & ⊢ ⊥ = (ocv‘𝑊) ⇒ ⊢ (𝑆 ⊆ 𝑉 → ( ⊥ ‘𝑆) = {𝑥 ∈ 𝑉 ∣ ∀𝑦 ∈ 𝑆 (𝑥 , 𝑦) = 0 }) | ||
| Theorem | elocv 21598* | Elementhood in the orthocomplement of a subset (normally a subspace) of a pre-Hilbert space. (Contributed by Mario Carneiro, 13-Oct-2015.) |
| ⊢ 𝑉 = (Base‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ 0 = (0g‘𝐹) & ⊢ ⊥ = (ocv‘𝑊) ⇒ ⊢ (𝐴 ∈ ( ⊥ ‘𝑆) ↔ (𝑆 ⊆ 𝑉 ∧ 𝐴 ∈ 𝑉 ∧ ∀𝑥 ∈ 𝑆 (𝐴 , 𝑥) = 0 )) | ||
| Theorem | ocvi 21599 | Property of a member of the orthocomplement of a subset. (Contributed by Mario Carneiro, 13-Oct-2015.) |
| ⊢ 𝑉 = (Base‘𝑊) & ⊢ , = (·𝑖‘𝑊) & ⊢ 𝐹 = (Scalar‘𝑊) & ⊢ 0 = (0g‘𝐹) & ⊢ ⊥ = (ocv‘𝑊) ⇒ ⊢ ((𝐴 ∈ ( ⊥ ‘𝑆) ∧ 𝐵 ∈ 𝑆) → (𝐴 , 𝐵) = 0 ) | ||
| Theorem | ocvss 21600 | The orthocomplement of a subset is a subset of the base. (Contributed by Mario Carneiro, 13-Oct-2015.) |
| ⊢ 𝑉 = (Base‘𝑊) & ⊢ ⊥ = (ocv‘𝑊) ⇒ ⊢ ( ⊥ ‘𝑆) ⊆ 𝑉 | ||
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