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| Type | Label | Description |
|---|---|---|
| Statement | ||
| Theorem | simpgntrivd 20201 | Simple groups are nontrivial. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ 0 = (0g‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ SimpGrp) ⇒ ⊢ (𝜑 → ¬ 𝐵 = { 0 }) | ||
| Theorem | simpgnideld 20202* | A simple group contains a nonidentity element. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ 0 = (0g‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ SimpGrp) ⇒ ⊢ (𝜑 → ∃𝑥 ∈ 𝐵 ¬ 𝑥 = 0 ) | ||
| Theorem | simpgnsgd 20203 | The only normal subgroups of a simple group are the group itself and the trivial group. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ 0 = (0g‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ SimpGrp) ⇒ ⊢ (𝜑 → (NrmSGrp‘𝐺) = {{ 0 }, 𝐵}) | ||
| Theorem | simpgnsgeqd 20204 | A normal subgroup of a simple group is either the whole group or the trivial subgroup. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ 0 = (0g‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ SimpGrp) & ⊢ (𝜑 → 𝐴 ∈ (NrmSGrp‘𝐺)) ⇒ ⊢ (𝜑 → (𝐴 = { 0 } ∨ 𝐴 = 𝐵)) | ||
| Theorem | 2nsgsimpgd 20205* | If any normal subgroup of a nontrivial group is either the trivial subgroup or the whole group, the group is simple. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ 0 = (0g‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ Grp) & ⊢ (𝜑 → ¬ { 0 } = 𝐵) & ⊢ ((𝜑 ∧ 𝑥 ∈ (NrmSGrp‘𝐺)) → (𝑥 = { 0 } ∨ 𝑥 = 𝐵)) ⇒ ⊢ (𝜑 → 𝐺 ∈ SimpGrp) | ||
| Theorem | simpgnsgbid 20206 | A nontrivial group is simple if and only if its normal subgroups are exactly the group itself and the trivial subgroup. (Contributed by Rohan Ridenour, 4-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ 0 = (0g‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ Grp) & ⊢ (𝜑 → ¬ { 0 } = 𝐵) ⇒ ⊢ (𝜑 → (𝐺 ∈ SimpGrp ↔ (NrmSGrp‘𝐺) = {{ 0 }, 𝐵})) | ||
| Theorem | ablsimpnosubgd 20207 | A subgroup of an abelian simple group containing a nonidentity element is the whole group. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ 0 = (0g‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ Abel) & ⊢ (𝜑 → 𝐺 ∈ SimpGrp) & ⊢ (𝜑 → 𝑆 ∈ (SubGrp‘𝐺)) & ⊢ (𝜑 → 𝐴 ∈ 𝑆) & ⊢ (𝜑 → ¬ 𝐴 = 0 ) ⇒ ⊢ (𝜑 → 𝑆 = 𝐵) | ||
| Theorem | ablsimpg1gend 20208* | An abelian simple group is generated by any non-identity element. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ 0 = (0g‘𝐺) & ⊢ · = (.g‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ Abel) & ⊢ (𝜑 → 𝐺 ∈ SimpGrp) & ⊢ (𝜑 → 𝐴 ∈ 𝐵) & ⊢ (𝜑 → ¬ 𝐴 = 0 ) & ⊢ (𝜑 → 𝐶 ∈ 𝐵) ⇒ ⊢ (𝜑 → ∃𝑛 ∈ ℤ 𝐶 = (𝑛 · 𝐴)) | ||
| Theorem | ablsimpgcygd 20209 | An abelian simple group is cyclic. (Contributed by Rohan Ridenour, 3-Aug-2023.) (Proof shortened by Rohan Ridenour, 31-Oct-2023.) |
| ⊢ (𝜑 → 𝐺 ∈ Abel) & ⊢ (𝜑 → 𝐺 ∈ SimpGrp) ⇒ ⊢ (𝜑 → 𝐺 ∈ CycGrp) | ||
| Theorem | ablsimpgfindlem1 20210* | Lemma for ablsimpgfind 20213. An element of an abelian finite simple group which doesn't square to the identity has finite order. (Contributed by Rohan Ridenour, 3-Aug-2023.) (Proof shortened by Rohan Ridenour, 31-Oct-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ 0 = (0g‘𝐺) & ⊢ · = (.g‘𝐺) & ⊢ 𝑂 = (od‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ Abel) & ⊢ (𝜑 → 𝐺 ∈ SimpGrp) ⇒ ⊢ (((𝜑 ∧ 𝑥 ∈ 𝐵) ∧ (2 · 𝑥) ≠ 0 ) → (𝑂‘𝑥) ≠ 0) | ||
| Theorem | ablsimpgfindlem2 20211* | Lemma for ablsimpgfind 20213. An element of an abelian finite simple group which squares to the identity has finite order. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ 0 = (0g‘𝐺) & ⊢ · = (.g‘𝐺) & ⊢ 𝑂 = (od‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ Abel) & ⊢ (𝜑 → 𝐺 ∈ SimpGrp) ⇒ ⊢ (((𝜑 ∧ 𝑥 ∈ 𝐵) ∧ (2 · 𝑥) = 0 ) → (𝑂‘𝑥) ≠ 0) | ||
| Theorem | cycsubggenodd 20212* | Relationship between the order of a subgroup and the order of a generator of the subgroup. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ · = (.g‘𝐺) & ⊢ 𝑂 = (od‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ Grp) & ⊢ (𝜑 → 𝐴 ∈ 𝐵) & ⊢ (𝜑 → 𝐶 = ran (𝑛 ∈ ℤ ↦ (𝑛 · 𝐴))) ⇒ ⊢ (𝜑 → (𝑂‘𝐴) = if(𝐶 ∈ Fin, (♯‘𝐶), 0)) | ||
| Theorem | ablsimpgfind 20213 | An abelian simple group is finite. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ Abel) & ⊢ (𝜑 → 𝐺 ∈ SimpGrp) ⇒ ⊢ (𝜑 → 𝐵 ∈ Fin) | ||
| Theorem | fincygsubgd 20214* | The subgroup referenced in fincygsubgodd 20215 is a subgroup. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ · = (.g‘𝐺) & ⊢ 𝐻 = (𝑛 ∈ ℤ ↦ (𝑛 · (𝐶 · 𝐴))) & ⊢ (𝜑 → 𝐺 ∈ Grp) & ⊢ (𝜑 → 𝐴 ∈ 𝐵) & ⊢ (𝜑 → 𝐶 ∈ ℕ) ⇒ ⊢ (𝜑 → ran 𝐻 ∈ (SubGrp‘𝐺)) | ||
| Theorem | fincygsubgodd 20215* | Calculate the order of a subgroup of a finite cyclic group. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ · = (.g‘𝐺) & ⊢ 𝐷 = ((♯‘𝐵) / 𝐶) & ⊢ 𝐹 = (𝑛 ∈ ℤ ↦ (𝑛 · 𝐴)) & ⊢ 𝐻 = (𝑛 ∈ ℤ ↦ (𝑛 · (𝐶 · 𝐴))) & ⊢ (𝜑 → 𝐺 ∈ Grp) & ⊢ (𝜑 → 𝐴 ∈ 𝐵) & ⊢ (𝜑 → ran 𝐹 = 𝐵) & ⊢ (𝜑 → 𝐶 ∥ (♯‘𝐵)) & ⊢ (𝜑 → 𝐵 ∈ Fin) & ⊢ (𝜑 → 𝐶 ∈ ℕ) ⇒ ⊢ (𝜑 → (♯‘ran 𝐻) = 𝐷) | ||
| Theorem | fincygsubgodexd 20216* | A finite cyclic group has subgroups of every possible order. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ CycGrp) & ⊢ (𝜑 → 𝐶 ∥ (♯‘𝐵)) & ⊢ (𝜑 → 𝐵 ∈ Fin) & ⊢ (𝜑 → 𝐶 ∈ ℕ) ⇒ ⊢ (𝜑 → ∃𝑥 ∈ (SubGrp‘𝐺)(♯‘𝑥) = 𝐶) | ||
| Theorem | prmgrpsimpgd 20217 | A group of prime order is simple. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ Grp) & ⊢ (𝜑 → (♯‘𝐵) ∈ ℙ) ⇒ ⊢ (𝜑 → 𝐺 ∈ SimpGrp) | ||
| Theorem | ablsimpgprmd 20218 | An abelian simple group has prime order. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ Abel) & ⊢ (𝜑 → 𝐺 ∈ SimpGrp) ⇒ ⊢ (𝜑 → (♯‘𝐵) ∈ ℙ) | ||
| Theorem | ablsimpgd 20219 | An abelian group is simple if and only if its order is prime. (Contributed by Rohan Ridenour, 3-Aug-2023.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ Abel) ⇒ ⊢ (𝜑 → (𝐺 ∈ SimpGrp ↔ (♯‘𝐵) ∈ ℙ)) | ||
| Syntax | comnd 20220 | Extend class notation with the class of all right ordered monoids. |
| class oMnd | ||
| Syntax | cogrp 20221 | Extend class notation with the class of all right ordered groups. |
| class oGrp | ||
| Definition | df-omnd 20222* | Define class of all right ordered monoids. An ordered monoid is a monoid with a total ordering compatible with its operation. It is possible to use this definition also for left ordered monoids, by applying it to (oppg‘𝑀). (Contributed by Thierry Arnoux, 13-Mar-2018.) |
| ⊢ oMnd = {𝑔 ∈ Mnd ∣ [(Base‘𝑔) / 𝑣][(+g‘𝑔) / 𝑝][(le‘𝑔) / 𝑙](𝑔 ∈ Toset ∧ ∀𝑎 ∈ 𝑣 ∀𝑏 ∈ 𝑣 ∀𝑐 ∈ 𝑣 (𝑎𝑙𝑏 → (𝑎𝑝𝑐)𝑙(𝑏𝑝𝑐)))} | ||
| Definition | df-ogrp 20223 | Define class of all ordered groups. An ordered group is a group with a total ordering compatible with its operation. (Contributed by Thierry Arnoux, 13-Mar-2018.) |
| ⊢ oGrp = (Grp ∩ oMnd) | ||
| Theorem | isomnd 20224* | A (left) ordered monoid is a monoid with a total ordering compatible with its operation. (Contributed by Thierry Arnoux, 30-Jan-2018.) |
| ⊢ 𝐵 = (Base‘𝑀) & ⊢ + = (+g‘𝑀) & ⊢ ≤ = (le‘𝑀) ⇒ ⊢ (𝑀 ∈ oMnd ↔ (𝑀 ∈ Mnd ∧ 𝑀 ∈ Toset ∧ ∀𝑎 ∈ 𝐵 ∀𝑏 ∈ 𝐵 ∀𝑐 ∈ 𝐵 (𝑎 ≤ 𝑏 → (𝑎 + 𝑐) ≤ (𝑏 + 𝑐)))) | ||
| Theorem | isogrp 20225 | A (left-)ordered group is a group with a total ordering compatible with its operations. (Contributed by Thierry Arnoux, 23-Mar-2018.) |
| ⊢ (𝐺 ∈ oGrp ↔ (𝐺 ∈ Grp ∧ 𝐺 ∈ oMnd)) | ||
| Theorem | ogrpgrp 20226 | A left-ordered group is a group. (Contributed by Thierry Arnoux, 9-Jul-2018.) |
| ⊢ (𝐺 ∈ oGrp → 𝐺 ∈ Grp) | ||
| Theorem | omndmnd 20227 | A left-ordered monoid is a monoid. (Contributed by Thierry Arnoux, 13-Mar-2018.) |
| ⊢ (𝑀 ∈ oMnd → 𝑀 ∈ Mnd) | ||
| Theorem | omndtos 20228 | A left-ordered monoid is a totally ordered set. (Contributed by Thierry Arnoux, 13-Mar-2018.) |
| ⊢ (𝑀 ∈ oMnd → 𝑀 ∈ Toset) | ||
| Theorem | omndadd 20229 | In an ordered monoid, the ordering is compatible with group addition. (Contributed by Thierry Arnoux, 30-Jan-2018.) |
| ⊢ 𝐵 = (Base‘𝑀) & ⊢ ≤ = (le‘𝑀) & ⊢ + = (+g‘𝑀) ⇒ ⊢ ((𝑀 ∈ oMnd ∧ (𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ 𝑍 ∈ 𝐵) ∧ 𝑋 ≤ 𝑌) → (𝑋 + 𝑍) ≤ (𝑌 + 𝑍)) | ||
| Theorem | omndaddr 20230 | In a right ordered monoid, the ordering is compatible with group addition. (Contributed by Thierry Arnoux, 30-Jan-2018.) |
| ⊢ 𝐵 = (Base‘𝑀) & ⊢ ≤ = (le‘𝑀) & ⊢ + = (+g‘𝑀) ⇒ ⊢ (((oppg‘𝑀) ∈ oMnd ∧ (𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ 𝑍 ∈ 𝐵) ∧ 𝑋 ≤ 𝑌) → (𝑍 + 𝑋) ≤ (𝑍 + 𝑌)) | ||
| Theorem | omndadd2d 20231 | In a commutative left ordered monoid, the ordering is compatible with monoid addition. Double addition version. (Contributed by Thierry Arnoux, 30-Jan-2018.) |
| ⊢ 𝐵 = (Base‘𝑀) & ⊢ ≤ = (le‘𝑀) & ⊢ + = (+g‘𝑀) & ⊢ (𝜑 → 𝑀 ∈ oMnd) & ⊢ (𝜑 → 𝑊 ∈ 𝐵) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐵) & ⊢ (𝜑 → 𝑍 ∈ 𝐵) & ⊢ (𝜑 → 𝑋 ≤ 𝑍) & ⊢ (𝜑 → 𝑌 ≤ 𝑊) & ⊢ (𝜑 → 𝑀 ∈ CMnd) ⇒ ⊢ (𝜑 → (𝑋 + 𝑌) ≤ (𝑍 + 𝑊)) | ||
| Theorem | omndadd2rd 20232 | In a left- and right- ordered monoid, the ordering is compatible with monoid addition. Double addition version. (Contributed by Thierry Arnoux, 2-May-2018.) |
| ⊢ 𝐵 = (Base‘𝑀) & ⊢ ≤ = (le‘𝑀) & ⊢ + = (+g‘𝑀) & ⊢ (𝜑 → 𝑀 ∈ oMnd) & ⊢ (𝜑 → 𝑊 ∈ 𝐵) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐵) & ⊢ (𝜑 → 𝑍 ∈ 𝐵) & ⊢ (𝜑 → 𝑋 ≤ 𝑍) & ⊢ (𝜑 → 𝑌 ≤ 𝑊) & ⊢ (𝜑 → (oppg‘𝑀) ∈ oMnd) ⇒ ⊢ (𝜑 → (𝑋 + 𝑌) ≤ (𝑍 + 𝑊)) | ||
| Theorem | submomnd 20233 | A submonoid of an ordered monoid is also ordered. (Contributed by Thierry Arnoux, 23-Mar-2018.) |
| ⊢ ((𝑀 ∈ oMnd ∧ (𝑀 ↾s 𝐴) ∈ Mnd) → (𝑀 ↾s 𝐴) ∈ oMnd) | ||
| Theorem | omndmul2 20234 | In an ordered monoid, the ordering is compatible with group power. This version does not require the monoid to be commutative. (Contributed by Thierry Arnoux, 23-Mar-2018.) |
| ⊢ 𝐵 = (Base‘𝑀) & ⊢ ≤ = (le‘𝑀) & ⊢ · = (.g‘𝑀) & ⊢ 0 = (0g‘𝑀) ⇒ ⊢ ((𝑀 ∈ oMnd ∧ (𝑋 ∈ 𝐵 ∧ 𝑁 ∈ ℕ0) ∧ 0 ≤ 𝑋) → 0 ≤ (𝑁 · 𝑋)) | ||
| Theorem | omndmul3 20235 | In an ordered monoid, the ordering is compatible with group power. This version does not require the monoid to be commutative. (Contributed by Thierry Arnoux, 23-Mar-2018.) |
| ⊢ 𝐵 = (Base‘𝑀) & ⊢ ≤ = (le‘𝑀) & ⊢ · = (.g‘𝑀) & ⊢ 0 = (0g‘𝑀) & ⊢ (𝜑 → 𝑀 ∈ oMnd) & ⊢ (𝜑 → 𝑁 ∈ ℕ0) & ⊢ (𝜑 → 𝑃 ∈ ℕ0) & ⊢ (𝜑 → 𝑁 ≤ 𝑃) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 0 ≤ 𝑋) ⇒ ⊢ (𝜑 → (𝑁 · 𝑋) ≤ (𝑃 · 𝑋)) | ||
| Theorem | omndmul 20236 | In a commutative ordered monoid, the ordering is compatible with group power. (Contributed by Thierry Arnoux, 30-Jan-2018.) |
| ⊢ 𝐵 = (Base‘𝑀) & ⊢ ≤ = (le‘𝑀) & ⊢ · = (.g‘𝑀) & ⊢ (𝜑 → 𝑀 ∈ oMnd) & ⊢ (𝜑 → 𝑀 ∈ CMnd) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐵) & ⊢ (𝜑 → 𝑁 ∈ ℕ0) & ⊢ (𝜑 → 𝑋 ≤ 𝑌) ⇒ ⊢ (𝜑 → (𝑁 · 𝑋) ≤ (𝑁 · 𝑌)) | ||
| Theorem | ogrpinv0le 20237 | In an ordered group, the ordering is compatible with group inverse. (Contributed by Thierry Arnoux, 3-Sep-2018.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ ≤ = (le‘𝐺) & ⊢ 𝐼 = (invg‘𝐺) & ⊢ 0 = (0g‘𝐺) ⇒ ⊢ ((𝐺 ∈ oGrp ∧ 𝑋 ∈ 𝐵) → ( 0 ≤ 𝑋 ↔ (𝐼‘𝑋) ≤ 0 )) | ||
| Theorem | ogrpsub 20238 | In an ordered group, the ordering is compatible with group subtraction. (Contributed by Thierry Arnoux, 30-Jan-2018.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ ≤ = (le‘𝐺) & ⊢ − = (-g‘𝐺) ⇒ ⊢ ((𝐺 ∈ oGrp ∧ (𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ 𝑍 ∈ 𝐵) ∧ 𝑋 ≤ 𝑌) → (𝑋 − 𝑍) ≤ (𝑌 − 𝑍)) | ||
| Theorem | ogrpaddlt 20239 | In an ordered group, strict ordering is compatible with group addition. (Contributed by Thierry Arnoux, 20-Jan-2018.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ < = (lt‘𝐺) & ⊢ + = (+g‘𝐺) ⇒ ⊢ ((𝐺 ∈ oGrp ∧ (𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ 𝑍 ∈ 𝐵) ∧ 𝑋 < 𝑌) → (𝑋 + 𝑍) < (𝑌 + 𝑍)) | ||
| Theorem | ogrpaddltbi 20240 | In a right ordered group, strict ordering is compatible with group addition. (Contributed by Thierry Arnoux, 3-Sep-2018.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ < = (lt‘𝐺) & ⊢ + = (+g‘𝐺) ⇒ ⊢ ((𝐺 ∈ oGrp ∧ (𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ 𝑍 ∈ 𝐵)) → (𝑋 < 𝑌 ↔ (𝑋 + 𝑍) < (𝑌 + 𝑍))) | ||
| Theorem | ogrpaddltrd 20241 | In a right ordered group, strict ordering is compatible with group addition. (Contributed by Thierry Arnoux, 3-Sep-2018.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ < = (lt‘𝐺) & ⊢ + = (+g‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ 𝑉) & ⊢ (𝜑 → (oppg‘𝐺) ∈ oGrp) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐵) & ⊢ (𝜑 → 𝑍 ∈ 𝐵) & ⊢ (𝜑 → 𝑋 < 𝑌) ⇒ ⊢ (𝜑 → (𝑍 + 𝑋) < (𝑍 + 𝑌)) | ||
| Theorem | ogrpaddltrbid 20242 | In a right ordered group, strict ordering is compatible with group addition. (Contributed by Thierry Arnoux, 4-Sep-2018.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ < = (lt‘𝐺) & ⊢ + = (+g‘𝐺) & ⊢ (𝜑 → 𝐺 ∈ 𝑉) & ⊢ (𝜑 → (oppg‘𝐺) ∈ oGrp) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐵) & ⊢ (𝜑 → 𝑍 ∈ 𝐵) ⇒ ⊢ (𝜑 → (𝑋 < 𝑌 ↔ (𝑍 + 𝑋) < (𝑍 + 𝑌))) | ||
| Theorem | ogrpsublt 20243 | In an ordered group, strict ordering is compatible with group addition. (Contributed by Thierry Arnoux, 3-Sep-2018.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ < = (lt‘𝐺) & ⊢ − = (-g‘𝐺) ⇒ ⊢ ((𝐺 ∈ oGrp ∧ (𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ 𝑍 ∈ 𝐵) ∧ 𝑋 < 𝑌) → (𝑋 − 𝑍) < (𝑌 − 𝑍)) | ||
| Theorem | ogrpinv0lt 20244 | In an ordered group, the ordering is compatible with group inverse. (Contributed by Thierry Arnoux, 3-Sep-2018.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ < = (lt‘𝐺) & ⊢ 𝐼 = (invg‘𝐺) & ⊢ 0 = (0g‘𝐺) ⇒ ⊢ ((𝐺 ∈ oGrp ∧ 𝑋 ∈ 𝐵) → ( 0 < 𝑋 ↔ (𝐼‘𝑋) < 0 )) | ||
| Theorem | ogrpinvlt 20245 | In an ordered group, the ordering is compatible with group inverse. (Contributed by Thierry Arnoux, 3-Sep-2018.) |
| ⊢ 𝐵 = (Base‘𝐺) & ⊢ < = (lt‘𝐺) & ⊢ 𝐼 = (invg‘𝐺) ⇒ ⊢ (((𝐺 ∈ oGrp ∧ (oppg‘𝐺) ∈ oGrp) ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑋 < 𝑌 ↔ (𝐼‘𝑌) < (𝐼‘𝑋))) | ||
| Theorem | gsumle 20246 | A finite sum in an ordered monoid is monotonic. This proof would be much easier in an ordered group, where an inverse element would be available. (Contributed by Thierry Arnoux, 13-Mar-2018.) |
| ⊢ 𝐵 = (Base‘𝑀) & ⊢ ≤ = (le‘𝑀) & ⊢ (𝜑 → 𝑀 ∈ oMnd) & ⊢ (𝜑 → 𝑀 ∈ CMnd) & ⊢ (𝜑 → 𝐴 ∈ Fin) & ⊢ (𝜑 → 𝐹:𝐴⟶𝐵) & ⊢ (𝜑 → 𝐺:𝐴⟶𝐵) & ⊢ (𝜑 → 𝐹 ∘r ≤ 𝐺) ⇒ ⊢ (𝜑 → (𝑀 Σg 𝐹) ≤ (𝑀 Σg 𝐺)) | ||
| Syntax | cmgp 20247 | Multiplicative group. |
| class mulGrp | ||
| Definition | df-mgp 20248 | Define a structure that puts the multiplication operation of a ring in the addition slot. Note that this will not actually be a group for the average ring, or even for a field, but it will be a monoid, and unitgrp 20498 shows that we get a group if we restrict to the elements that have inverses. This allows to formalize such notions as "the multiplication operation of a ring is a monoid" (ringmgp 20352) or "the multiplicative identity" in terms of the identity of a monoid (df-ur 20295). (Contributed by Mario Carneiro, 21-Dec-2014.) |
| ⊢ mulGrp = (𝑤 ∈ V ↦ (𝑤 sSet ⟨(+g‘ndx), (.r‘𝑤)⟩)) | ||
| Theorem | fnmgp 20249 | The multiplicative group operator is a function. (Contributed by Mario Carneiro, 11-Mar-2015.) |
| ⊢ mulGrp Fn V | ||
| Theorem | mgpval 20250 | Value of the multiplication group operation. (Contributed by Mario Carneiro, 21-Dec-2014.) |
| ⊢ 𝑀 = (mulGrp‘𝑅) & ⊢ · = (.r‘𝑅) ⇒ ⊢ 𝑀 = (𝑅 sSet ⟨(+g‘ndx), · ⟩) | ||
| Theorem | mgpplusg 20251 | Value of the group operation of the multiplication group. (Contributed by Mario Carneiro, 21-Dec-2014.) |
| ⊢ 𝑀 = (mulGrp‘𝑅) & ⊢ · = (.r‘𝑅) ⇒ ⊢ · = (+g‘𝑀) | ||
| Theorem | mgpbas 20252 | Base set of the multiplication group. (Contributed by Mario Carneiro, 21-Dec-2014.) (Revised by Mario Carneiro, 5-Oct-2015.) |
| ⊢ 𝑀 = (mulGrp‘𝑅) & ⊢ 𝐵 = (Base‘𝑅) ⇒ ⊢ 𝐵 = (Base‘𝑀) | ||
| Theorem | mgpsca 20253 | The multiplication monoid has the same (if any) scalars as the original ring. Mostly to simplify pwsmgp 20441. (Contributed by Mario Carneiro, 12-Mar-2015.) (Revised by Mario Carneiro, 5-May-2015.) |
| ⊢ 𝑀 = (mulGrp‘𝑅) & ⊢ 𝑆 = (Scalar‘𝑅) ⇒ ⊢ 𝑆 = (Scalar‘𝑀) | ||
| Theorem | mgptset 20254 | Topology component of the multiplication group. (Contributed by Mario Carneiro, 5-Oct-2015.) |
| ⊢ 𝑀 = (mulGrp‘𝑅) ⇒ ⊢ (TopSet‘𝑅) = (TopSet‘𝑀) | ||
| Theorem | mgptopn 20255 | Topology of the multiplication group. (Contributed by Mario Carneiro, 5-Oct-2015.) |
| ⊢ 𝑀 = (mulGrp‘𝑅) & ⊢ 𝐽 = (TopOpen‘𝑅) ⇒ ⊢ 𝐽 = (TopOpen‘𝑀) | ||
| Theorem | mgpds 20256 | Distance function of the multiplication group. (Contributed by Mario Carneiro, 5-Oct-2015.) |
| ⊢ 𝑀 = (mulGrp‘𝑅) & ⊢ 𝐵 = (dist‘𝑅) ⇒ ⊢ 𝐵 = (dist‘𝑀) | ||
| Theorem | mgpress 20257 | Subgroup commutes with the multiplicative group operator. (Contributed by Mario Carneiro, 10-Jan-2015.) (Proof shortened by AV, 18-Oct-2024.) |
| ⊢ 𝑆 = (𝑅 ↾s 𝐴) & ⊢ 𝑀 = (mulGrp‘𝑅) ⇒ ⊢ ((𝑅 ∈ 𝑉 ∧ 𝐴 ∈ 𝑊) → (𝑀 ↾s 𝐴) = (mulGrp‘𝑆)) | ||
| Theorem | prdsmgp 20258 | The multiplicative monoid of a product is the product of the multiplicative monoids of the factors. (Contributed by Mario Carneiro, 11-Mar-2015.) |
| ⊢ 𝑌 = (𝑆Xs𝑅) & ⊢ 𝑀 = (mulGrp‘𝑌) & ⊢ 𝑍 = (𝑆Xs(mulGrp ∘ 𝑅)) & ⊢ (𝜑 → 𝐼 ∈ 𝑉) & ⊢ (𝜑 → 𝑆 ∈ 𝑊) & ⊢ (𝜑 → 𝑅 Fn 𝐼) ⇒ ⊢ (𝜑 → ((Base‘𝑀) = (Base‘𝑍) ∧ (+g‘𝑀) = (+g‘𝑍))) | ||
| Theorem | elmgplsm 20259* | Membership in a product of two subsets of a multiplication group. (Contributed by Thierry Arnoux, 20-Jan-2024.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ 𝐺 = (mulGrp‘𝑅) & ⊢ × = (LSSum‘𝐺) & ⊢ (𝜑 → 𝐸 ⊆ 𝐵) & ⊢ (𝜑 → 𝐹 ⊆ 𝐵) ⇒ ⊢ (𝜑 → (𝑍 ∈ (𝐸 × 𝐹) ↔ ∃𝑥 ∈ 𝐸 ∃𝑦 ∈ 𝐹 𝑍 = (𝑥 · 𝑦))) | ||
| Theorem | elmgplsmd 20260 | Membership in a product of two subsets of a multiplication group, one direction. (Contributed by Thierry Arnoux, 13-Apr-2024.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ 𝐺 = (mulGrp‘𝑅) & ⊢ × = (LSSum‘𝐺) & ⊢ (𝜑 → 𝐸 ⊆ 𝐵) & ⊢ (𝜑 → 𝐹 ⊆ 𝐵) & ⊢ (𝜑 → 𝑋 ∈ 𝐸) & ⊢ (𝜑 → 𝑌 ∈ 𝐹) ⇒ ⊢ (𝜑 → (𝑋 · 𝑌) ∈ (𝐸 × 𝐹)) | ||
According to Wikipedia, "... in abstract algebra, a rng (or non-unital ring or pseudo-ring) is an algebraic structure satisfying the same properties as a [unital] ring, without assuming the existence of a multiplicative identity. The term "rng" (pronounced rung) is meant to suggest that it is a "ring" without "i", i.e. without the requirement for an "identity element"." (see https://en.wikipedia.org/wiki/Rng_(algebra), 28-Mar-2025). | ||
| Syntax | crng 20261 | Extend class notation with class of all non-unital rings. |
| class Rng | ||
| Definition | df-rng 20262* | Define the class of all non-unital rings. A non-unital ring (or rng, or pseudoring) is a set equipped with two everywhere-defined internal operations, whose first one is an additive abelian group operation and the second one is a multiplicative semigroup operation, and where the addition is left- and right-distributive for the multiplication. Definition of a pseudo-ring in section I.8.1 of [BourbakiAlg1] p. 93 or the definition of a ring in part Preliminaries of [Roman] p. 18. As almost always in mathematics, "non-unital" means "not necessarily unital". Therefore, by talking about a ring (in general) or a non-unital ring the "unital" case is always included. In contrast to a unital ring, the commutativity of addition must be postulated and cannot be proven from the other conditions. (Contributed by AV, 6-Jan-2020.) |
| ⊢ Rng = {𝑓 ∈ Abel ∣ ((mulGrp‘𝑓) ∈ Smgrp ∧ [(Base‘𝑓) / 𝑏][(+g‘𝑓) / 𝑝][(.r‘𝑓) / 𝑡]∀𝑥 ∈ 𝑏 ∀𝑦 ∈ 𝑏 ∀𝑧 ∈ 𝑏 ((𝑥𝑡(𝑦𝑝𝑧)) = ((𝑥𝑡𝑦)𝑝(𝑥𝑡𝑧)) ∧ ((𝑥𝑝𝑦)𝑡𝑧) = ((𝑥𝑡𝑧)𝑝(𝑦𝑡𝑧))))} | ||
| Theorem | isrng 20263* | The predicate "is a non-unital ring." (Contributed by AV, 6-Jan-2020.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ 𝐺 = (mulGrp‘𝑅) & ⊢ + = (+g‘𝑅) & ⊢ · = (.r‘𝑅) ⇒ ⊢ (𝑅 ∈ Rng ↔ (𝑅 ∈ Abel ∧ 𝐺 ∈ Smgrp ∧ ∀𝑥 ∈ 𝐵 ∀𝑦 ∈ 𝐵 ∀𝑧 ∈ 𝐵 ((𝑥 · (𝑦 + 𝑧)) = ((𝑥 · 𝑦) + (𝑥 · 𝑧)) ∧ ((𝑥 + 𝑦) · 𝑧) = ((𝑥 · 𝑧) + (𝑦 · 𝑧))))) | ||
| Theorem | rngabl 20264 | A non-unital ring is an (additive) abelian group. (Contributed by AV, 17-Feb-2020.) |
| ⊢ (𝑅 ∈ Rng → 𝑅 ∈ Abel) | ||
| Theorem | rngmgp 20265 | A non-unital ring is a semigroup under multiplication. (Contributed by AV, 17-Feb-2020.) |
| ⊢ 𝐺 = (mulGrp‘𝑅) ⇒ ⊢ (𝑅 ∈ Rng → 𝐺 ∈ Smgrp) | ||
| Theorem | rngmgpf 20266 | Restricted functionality of the multiplicative group on non-unital rings (mgpf 20361 analog). (Contributed by AV, 22-Feb-2025.) |
| ⊢ (mulGrp ↾ Rng):Rng⟶Smgrp | ||
| Theorem | rnggrp 20267 | A non-unital ring is a (additive) group. (Contributed by AV, 16-Feb-2025.) |
| ⊢ (𝑅 ∈ Rng → 𝑅 ∈ Grp) | ||
| Theorem | rngass 20268 | Associative law for the multiplication operation of a non-unital ring. (Contributed by NM, 27-Aug-2011.) (Revised by AV, 13-Feb-2025.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) ⇒ ⊢ ((𝑅 ∈ Rng ∧ (𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ 𝑍 ∈ 𝐵)) → ((𝑋 · 𝑌) · 𝑍) = (𝑋 · (𝑌 · 𝑍))) | ||
| Theorem | rngdi 20269 | Distributive law for the multiplication operation of a non-unital ring (left-distributivity). (Contributed by AV, 14-Feb-2025.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ + = (+g‘𝑅) & ⊢ · = (.r‘𝑅) ⇒ ⊢ ((𝑅 ∈ Rng ∧ (𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ 𝑍 ∈ 𝐵)) → (𝑋 · (𝑌 + 𝑍)) = ((𝑋 · 𝑌) + (𝑋 · 𝑍))) | ||
| Theorem | rngdir 20270 | Distributive law for the multiplication operation of a non-unital ring (right-distributivity). (Contributed by AV, 17-Apr-2020.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ + = (+g‘𝑅) & ⊢ · = (.r‘𝑅) ⇒ ⊢ ((𝑅 ∈ Rng ∧ (𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ 𝑍 ∈ 𝐵)) → ((𝑋 + 𝑌) · 𝑍) = ((𝑋 · 𝑍) + (𝑌 · 𝑍))) | ||
| Theorem | rngacl 20271 | Closure of the addition operation of a non-unital ring. (Contributed by AV, 16-Feb-2025.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ + = (+g‘𝑅) ⇒ ⊢ ((𝑅 ∈ Rng ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑋 + 𝑌) ∈ 𝐵) | ||
| Theorem | rng0cl 20272 | The zero element of a non-unital ring belongs to its base set. (Contributed by AV, 16-Feb-2025.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ 0 = (0g‘𝑅) ⇒ ⊢ (𝑅 ∈ Rng → 0 ∈ 𝐵) | ||
| Theorem | rngcl 20273 | Closure of the multiplication operation of a non-unital ring. (Contributed by AV, 17-Apr-2020.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) ⇒ ⊢ ((𝑅 ∈ Rng ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑋 · 𝑌) ∈ 𝐵) | ||
| Theorem | rnglz 20274 | The zero of a non-unital ring is a left-absorbing element. (Contributed by FL, 31-Aug-2009.) Generalization of ringlz 20409. (Revised by AV, 17-Apr-2020.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ 0 = (0g‘𝑅) ⇒ ⊢ ((𝑅 ∈ Rng ∧ 𝑋 ∈ 𝐵) → ( 0 · 𝑋) = 0 ) | ||
| Theorem | rngrz 20275 | The zero of a non-unital ring is a right-absorbing element. (Contributed by FL, 31-Aug-2009.) Generalization of ringrz 20410. (Revised by AV, 16-Feb-2025.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ 0 = (0g‘𝑅) ⇒ ⊢ ((𝑅 ∈ Rng ∧ 𝑋 ∈ 𝐵) → (𝑋 · 0 ) = 0 ) | ||
| Theorem | rngmneg1 20276 | Negation of a product in a non-unital ring (mulneg1 11668 analog). In contrast to ringmneg1 20420, the proof does not (and cannot) make use of the existence of a ring unity. (Contributed by AV, 17-Feb-2025.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ 𝑁 = (invg‘𝑅) & ⊢ (𝜑 → 𝑅 ∈ Rng) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐵) ⇒ ⊢ (𝜑 → ((𝑁‘𝑋) · 𝑌) = (𝑁‘(𝑋 · 𝑌))) | ||
| Theorem | rngmneg2 20277 | Negation of a product in a non-unital ring (mulneg2 11669 analog). In contrast to ringmneg2 20421, the proof does not (and cannot) make use of the existence of a ring unity. (Contributed by AV, 17-Feb-2025.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ 𝑁 = (invg‘𝑅) & ⊢ (𝜑 → 𝑅 ∈ Rng) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐵) ⇒ ⊢ (𝜑 → (𝑋 · (𝑁‘𝑌)) = (𝑁‘(𝑋 · 𝑌))) | ||
| Theorem | rngm2neg 20278 | Double negation of a product in a non-unital ring (mul2neg 11671 analog). (Contributed by Mario Carneiro, 4-Dec-2014.) Generalization of ringm2neg 20422. (Revised by AV, 17-Feb-2025.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ 𝑁 = (invg‘𝑅) & ⊢ (𝜑 → 𝑅 ∈ Rng) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐵) ⇒ ⊢ (𝜑 → ((𝑁‘𝑋) · (𝑁‘𝑌)) = (𝑋 · 𝑌)) | ||
| Theorem | rngansg 20279 | Every additive subgroup of a non-unital ring is normal. (Contributed by AV, 25-Feb-2025.) |
| ⊢ (𝑅 ∈ Rng → (NrmSGrp‘𝑅) = (SubGrp‘𝑅)) | ||
| Theorem | rngsubdi 20280 | Ring multiplication distributes over subtraction. (subdi 11665 analog.) (Contributed by Jeff Madsen, 19-Jun-2010.) (Revised by Mario Carneiro, 2-Jul-2014.) Generalization of ringsubdi 20423. (Revised by AV, 23-Feb-2025.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ − = (-g‘𝑅) & ⊢ (𝜑 → 𝑅 ∈ Rng) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐵) & ⊢ (𝜑 → 𝑍 ∈ 𝐵) ⇒ ⊢ (𝜑 → (𝑋 · (𝑌 − 𝑍)) = ((𝑋 · 𝑌) − (𝑋 · 𝑍))) | ||
| Theorem | rngsubdir 20281 | Ring multiplication distributes over subtraction. (subdir 11666 analog.) (Contributed by Jeff Madsen, 19-Jun-2010.) (Revised by Mario Carneiro, 2-Jul-2014.) Generalization of ringsubdir 20424. (Revised by AV, 23-Feb-2025.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ − = (-g‘𝑅) & ⊢ (𝜑 → 𝑅 ∈ Rng) & ⊢ (𝜑 → 𝑋 ∈ 𝐵) & ⊢ (𝜑 → 𝑌 ∈ 𝐵) & ⊢ (𝜑 → 𝑍 ∈ 𝐵) ⇒ ⊢ (𝜑 → ((𝑋 − 𝑌) · 𝑍) = ((𝑋 · 𝑍) − (𝑌 · 𝑍))) | ||
| Theorem | isrngd 20282* | Properties that determine a non-unital ring. (Contributed by AV, 14-Feb-2025.) |
| ⊢ (𝜑 → 𝐵 = (Base‘𝑅)) & ⊢ (𝜑 → + = (+g‘𝑅)) & ⊢ (𝜑 → · = (.r‘𝑅)) & ⊢ (𝜑 → 𝑅 ∈ Abel) & ⊢ ((𝜑 ∧ 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵) → (𝑥 · 𝑦) ∈ 𝐵) & ⊢ ((𝜑 ∧ (𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵)) → ((𝑥 · 𝑦) · 𝑧) = (𝑥 · (𝑦 · 𝑧))) & ⊢ ((𝜑 ∧ (𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵)) → (𝑥 · (𝑦 + 𝑧)) = ((𝑥 · 𝑦) + (𝑥 · 𝑧))) & ⊢ ((𝜑 ∧ (𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵)) → ((𝑥 + 𝑦) · 𝑧) = ((𝑥 · 𝑧) + (𝑦 · 𝑧))) ⇒ ⊢ (𝜑 → 𝑅 ∈ Rng) | ||
| Theorem | rngpropd 20283* | If two structures have the same base set, and the values of their group (addition) and ring (multiplication) operations are equal for all pairs of elements of the base set, one is a non-unital ring iff the other one is. (Contributed by AV, 15-Feb-2025.) |
| ⊢ (𝜑 → 𝐵 = (Base‘𝐾)) & ⊢ (𝜑 → 𝐵 = (Base‘𝐿)) & ⊢ ((𝜑 ∧ (𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵)) → (𝑥(+g‘𝐾)𝑦) = (𝑥(+g‘𝐿)𝑦)) & ⊢ ((𝜑 ∧ (𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵)) → (𝑥(.r‘𝐾)𝑦) = (𝑥(.r‘𝐿)𝑦)) ⇒ ⊢ (𝜑 → (𝐾 ∈ Rng ↔ 𝐿 ∈ Rng)) | ||
| Theorem | prdsmulrngcl 20284 | Closure of the multiplication in a structure product of non-unital rings. (Contributed by Mario Carneiro, 11-Mar-2015.) Generalization of prdsmulrcl 20434. (Revised by AV, 21-Feb-2025.) |
| ⊢ 𝑌 = (𝑆Xs𝑅) & ⊢ 𝐵 = (Base‘𝑌) & ⊢ · = (.r‘𝑌) & ⊢ (𝜑 → 𝑆 ∈ 𝑉) & ⊢ (𝜑 → 𝐼 ∈ 𝑊) & ⊢ (𝜑 → 𝑅:𝐼⟶Rng) & ⊢ (𝜑 → 𝐹 ∈ 𝐵) & ⊢ (𝜑 → 𝐺 ∈ 𝐵) ⇒ ⊢ (𝜑 → (𝐹 · 𝐺) ∈ 𝐵) | ||
| Theorem | prdsrngd 20285 | A product of non-unital rings is a non-unital ring. (Contributed by AV, 22-Feb-2025.) |
| ⊢ 𝑌 = (𝑆Xs𝑅) & ⊢ (𝜑 → 𝐼 ∈ 𝑊) & ⊢ (𝜑 → 𝑆 ∈ 𝑉) & ⊢ (𝜑 → 𝑅:𝐼⟶Rng) ⇒ ⊢ (𝜑 → 𝑌 ∈ Rng) | ||
| Theorem | imasrng 20286* | The image structure of a non-unital ring is a non-unital ring (imasring 20445 analog). (Contributed by AV, 22-Feb-2025.) |
| ⊢ (𝜑 → 𝑈 = (𝐹 “s 𝑅)) & ⊢ (𝜑 → 𝑉 = (Base‘𝑅)) & ⊢ + = (+g‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ (𝜑 → 𝐹:𝑉–onto→𝐵) & ⊢ ((𝜑 ∧ (𝑎 ∈ 𝑉 ∧ 𝑏 ∈ 𝑉) ∧ (𝑝 ∈ 𝑉 ∧ 𝑞 ∈ 𝑉)) → (((𝐹‘𝑎) = (𝐹‘𝑝) ∧ (𝐹‘𝑏) = (𝐹‘𝑞)) → (𝐹‘(𝑎 + 𝑏)) = (𝐹‘(𝑝 + 𝑞)))) & ⊢ ((𝜑 ∧ (𝑎 ∈ 𝑉 ∧ 𝑏 ∈ 𝑉) ∧ (𝑝 ∈ 𝑉 ∧ 𝑞 ∈ 𝑉)) → (((𝐹‘𝑎) = (𝐹‘𝑝) ∧ (𝐹‘𝑏) = (𝐹‘𝑞)) → (𝐹‘(𝑎 · 𝑏)) = (𝐹‘(𝑝 · 𝑞)))) & ⊢ (𝜑 → 𝑅 ∈ Rng) ⇒ ⊢ (𝜑 → 𝑈 ∈ Rng) | ||
| Theorem | imasrngf1 20287 | The image of a non-unital ring under an injection is a non-unital ring (imasmndf1 18865 analog). (Contributed by AV, 22-Feb-2025.) |
| ⊢ 𝑈 = (𝐹 “s 𝑅) & ⊢ 𝑉 = (Base‘𝑅) ⇒ ⊢ ((𝐹:𝑉–1-1→𝐵 ∧ 𝑅 ∈ Rng) → 𝑈 ∈ Rng) | ||
| Theorem | xpsrngd 20288 | A product of two non-unital rings is a non-unital ring (xpsmnd 18866 analog). (Contributed by AV, 22-Feb-2025.) |
| ⊢ 𝑌 = (𝑆 ×s 𝑅) & ⊢ (𝜑 → 𝑆 ∈ Rng) & ⊢ (𝜑 → 𝑅 ∈ Rng) ⇒ ⊢ (𝜑 → 𝑌 ∈ Rng) | ||
| Theorem | qusrng 20289* | The quotient structure of a non-unital ring is a non-unital ring (qusring2 20449 analog). (Contributed by AV, 23-Feb-2025.) |
| ⊢ (𝜑 → 𝑈 = (𝑅 /s ∼ )) & ⊢ (𝜑 → 𝑉 = (Base‘𝑅)) & ⊢ + = (+g‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ (𝜑 → ∼ Er 𝑉) & ⊢ (𝜑 → ((𝑎 ∼ 𝑝 ∧ 𝑏 ∼ 𝑞) → (𝑎 + 𝑏) ∼ (𝑝 + 𝑞))) & ⊢ (𝜑 → ((𝑎 ∼ 𝑝 ∧ 𝑏 ∼ 𝑞) → (𝑎 · 𝑏) ∼ (𝑝 · 𝑞))) & ⊢ (𝜑 → 𝑅 ∈ Rng) ⇒ ⊢ (𝜑 → 𝑈 ∈ Rng) | ||
| Theorem | rng1zrlem 20290 | Lemma for rng1zr 20291 and srg1zr 20328. (Contributed by FL, 13-Feb-2010.) (Revised by AV, 18-Jun-2026.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ + = (+g‘𝑅) & ⊢ ∗ = (.r‘𝑅) ⇒ ⊢ (((𝑅 ∈ Mgm ∧ (mulGrp‘𝑅) ∈ Mgm) ∧ ( + Fn (𝐵 × 𝐵) ∧ ∗ Fn (𝐵 × 𝐵)) ∧ 𝑍 ∈ 𝐵) → (𝐵 = {𝑍} ↔ ( + = {⟨⟨𝑍, 𝑍⟩, 𝑍⟩} ∧ ∗ = {⟨⟨𝑍, 𝑍⟩, 𝑍⟩}))) | ||
| Theorem | rng1zr 20291 | The only ring with a base set consisting of one element is the zero ring (at least if its operations are internal binary operations). (Contributed by FL, 13-Feb-2010.) (Revised by AV, 18-Jun-2026.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ + = (+g‘𝑅) & ⊢ ∗ = (.r‘𝑅) ⇒ ⊢ (((𝑅 ∈ Rng ∧ + Fn (𝐵 × 𝐵) ∧ ∗ Fn (𝐵 × 𝐵)) ∧ 𝑍 ∈ 𝐵) → (𝐵 = {𝑍} ↔ ( + = {⟨⟨𝑍, 𝑍⟩, 𝑍⟩} ∧ ∗ = {⟨⟨𝑍, 𝑍⟩, 𝑍⟩}))) | ||
| Theorem | rngen1zr 20292 | The only ring with one element is the zero ring (at least if its operations are internal binary operations). (Contributed by FL, 14-Feb-2010.) (Revised by AV, 18-Jun-2026.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ + = (+g‘𝑅) & ⊢ ∗ = (.r‘𝑅) ⇒ ⊢ (((𝑅 ∈ Rng ∧ + Fn (𝐵 × 𝐵) ∧ ∗ Fn (𝐵 × 𝐵)) ∧ 𝑍 ∈ 𝐵) → (𝐵 ≈ 1o ↔ ( + = {⟨⟨𝑍, 𝑍⟩, 𝑍⟩} ∧ ∗ = {⟨⟨𝑍, 𝑍⟩, 𝑍⟩}))) | ||
| Theorem | rngen1zr0 20293 | The only ring with one element is the zero ring (at least if its operations are internal binary operations). (Contributed by FL, 15-Feb-2010.) (Revised by AV, 18-Jun-2026.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ + = (+g‘𝑅) & ⊢ ∗ = (.r‘𝑅) & ⊢ 0 = (0g‘𝑅) ⇒ ⊢ ((𝑅 ∈ Rng ∧ + Fn (𝐵 × 𝐵) ∧ ∗ Fn (𝐵 × 𝐵)) → (𝐵 ≈ 1o ↔ ( + = {⟨⟨ 0 , 0 ⟩, 0 ⟩} ∧ ∗ = {⟨⟨ 0 , 0 ⟩, 0 ⟩}))) | ||
In Wikipedia "Identity element", see https://en.wikipedia.org/wiki/Identity_element (18-Jan-2025): "... an identity with respect to multiplication is called a multiplicative identity (often denoted as 1). ... The distinction between additive and multiplicative identity is used most often for sets that support both binary operations, such as rings, integral domains, and fields. The multiplicative identity is often called unity in the latter context (a ring with unity). This should not be confused with a unit in ring theory, which is any element having a multiplicative inverse. By its own definition, unity itself is necessarily a unit." Calling the multiplicative identity of a ring a unity is taken from the definition of a ring with unity in section 17.3 of [BeauregardFraleigh] p. 135, "A ring ( R , + , . ) is a ring with unity if R is not the zero ring and ( R , . ) is a monoid. In this case, the identity element of ( R , . ) is denoted by 1 and is called the unity of R." This definition of a "ring with unity" corresponds to our definition of a unital ring (see df-ring 20348). Some authors call the multiplicative identity "unit" or "unit element" (for example in section I, 2.2 of [BourbakiAlg1] p. 14, definition in section 1.3 of [Hall] p. 4, or in section I, 1 of [Lang] p. 3), whereas other authors use the term "unit" for an element having a multiplicative inverse (for example in section 17.3 of [BeauregardFraleigh] p. 135, in definition in [Roman] p. 26, or even in section II, 1 of [Lang] p. 84). Sometimes, the multiplicative identity is simply called "one" (see, for example, chapter 8 in [Schechter] p. 180). To avoid this ambiguity of the term "unit", also mentioned in Wikipedia, we call the multiplicative identity of a structure with a multiplication (usually a ring) a "ring unity", or straightly "multiplicative identity". The term "unit" will be used for an element having a multiplicative inverse (see df-unit 20473), and we have "the ring unity is a unit", see 1unit 20489. | ||
| Syntax | cur 20294 | Extend class notation with ring unity. |
| class 1r | ||
| Definition | df-ur 20295 |
Define the multiplicative identity, i.e., the monoid identity (df-0g 17519)
of the multiplicative monoid (df-mgp 20248) of a ring-like structure. This
multiplicative identity is also called "ring unity" or
"unity element".
This definition works by transferring the multiplicative operation from the .r slot to the +g slot and then looking at the element which is then the 0g element, that is an identity with respect to the operation which started out in the .r slot. See also dfur2 20297, which derives the "traditional" definition as the unique element of a ring which is left- and right-neutral under multiplication. (Contributed by NM, 27-Aug-2011.) (Revised by Mario Carneiro, 27-Dec-2014.) |
| ⊢ 1r = (0g ∘ mulGrp) | ||
| Theorem | ringidval 20296 | The value of the unity element of a ring. (Contributed by NM, 27-Aug-2011.) (Revised by Mario Carneiro, 27-Dec-2014.) |
| ⊢ 𝐺 = (mulGrp‘𝑅) & ⊢ 1 = (1r‘𝑅) ⇒ ⊢ 1 = (0g‘𝐺) | ||
| Theorem | dfur2 20297* | The multiplicative identity is the unique element of the ring that is left- and right-neutral on all elements under multiplication. (Contributed by Mario Carneiro, 10-Jan-2015.) |
| ⊢ 𝐵 = (Base‘𝑅) & ⊢ · = (.r‘𝑅) & ⊢ 1 = (1r‘𝑅) ⇒ ⊢ 1 = (℩𝑒(𝑒 ∈ 𝐵 ∧ ∀𝑥 ∈ 𝐵 ((𝑒 · 𝑥) = 𝑥 ∧ (𝑥 · 𝑒) = 𝑥))) | ||
| Theorem | ringurd 20298* | Deduce the unity element of a ring from its properties. (Contributed by Thierry Arnoux, 6-Sep-2016.) |
| ⊢ (𝜑 → 𝐵 = (Base‘𝑅)) & ⊢ (𝜑 → · = (.r‘𝑅)) & ⊢ (𝜑 → 1 ∈ 𝐵) & ⊢ ((𝜑 ∧ 𝑥 ∈ 𝐵) → ( 1 · 𝑥) = 𝑥) & ⊢ ((𝜑 ∧ 𝑥 ∈ 𝐵) → (𝑥 · 1 ) = 𝑥) ⇒ ⊢ (𝜑 → 1 = (1r‘𝑅)) | ||
| Syntax | csrg 20299 | Extend class notation with the class of all semirings. |
| class SRing | ||
| Definition | df-srg 20300* | Define class of all semirings. A semiring is a set equipped with two everywhere-defined internal operations, whose first one is an additive commutative monoid structure and the second one is a multiplicative monoid structure, and where multiplication is (left- and right-) distributive over addition. Like with rings (df-ring 20348), the additive identity is an absorbing element of the multiplicative law, but in the case of semirings, this has to be part of the definition, as it cannot be deduced from distributivity alone. Definition of [Golan] p. 1. Note that our semirings are unital. Such semirings are sometimes called "rigs", being "rings without negatives". (Contributed by Thierry Arnoux, 21-Mar-2018.) |
| ⊢ SRing = {𝑓 ∈ CMnd ∣ ((mulGrp‘𝑓) ∈ Mnd ∧ [(Base‘𝑓) / 𝑟][(+g‘𝑓) / 𝑝][(.r‘𝑓) / 𝑡][(0g‘𝑓) / 𝑛]∀𝑥 ∈ 𝑟 (∀𝑦 ∈ 𝑟 ∀𝑧 ∈ 𝑟 ((𝑥𝑡(𝑦𝑝𝑧)) = ((𝑥𝑡𝑦)𝑝(𝑥𝑡𝑧)) ∧ ((𝑥𝑝𝑦)𝑡𝑧) = ((𝑥𝑡𝑧)𝑝(𝑦𝑡𝑧))) ∧ ((𝑛𝑡𝑥) = 𝑛 ∧ (𝑥𝑡𝑛) = 𝑛)))} | ||
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