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Type | Label | Description |
---|---|---|
Statement | ||
Theorem | trclubi 15001* | The Cartesian product of the domain and range of a relation is an upper bound for its transitive closure. (Contributed by RP, 2-Jan-2020.) (Revised by RP, 28-Apr-2020.) (Revised by AV, 26-Mar-2021.) |
⊢ Rel 𝑅 & ⊢ 𝑅 ∈ V ⇒ ⊢ ∩ {𝑠 ∣ (𝑅 ⊆ 𝑠 ∧ (𝑠 ∘ 𝑠) ⊆ 𝑠)} ⊆ (dom 𝑅 × ran 𝑅) | ||
Theorem | trclubgi 15002* | The union with the Cartesian product of its domain and range is an upper bound for a set's transitive closure. (Contributed by RP, 3-Jan-2020.) (Revised by RP, 28-Apr-2020.) (Revised by AV, 26-Mar-2021.) |
⊢ 𝑅 ∈ V ⇒ ⊢ ∩ {𝑠 ∣ (𝑅 ⊆ 𝑠 ∧ (𝑠 ∘ 𝑠) ⊆ 𝑠)} ⊆ (𝑅 ∪ (dom 𝑅 × ran 𝑅)) | ||
Theorem | trclub 15003* | The Cartesian product of the domain and range of a relation is an upper bound for its transitive closure. (Contributed by RP, 17-May-2020.) |
⊢ ((𝑅 ∈ 𝑉 ∧ Rel 𝑅) → ∩ {𝑟 ∣ (𝑅 ⊆ 𝑟 ∧ (𝑟 ∘ 𝑟) ⊆ 𝑟)} ⊆ (dom 𝑅 × ran 𝑅)) | ||
Theorem | trclubg 15004* | The union with the Cartesian product of its domain and range is an upper bound for a set's transitive closure (as a relation). (Contributed by RP, 17-May-2020.) |
⊢ (𝑅 ∈ 𝑉 → ∩ {𝑟 ∣ (𝑅 ⊆ 𝑟 ∧ (𝑟 ∘ 𝑟) ⊆ 𝑟)} ⊆ (𝑅 ∪ (dom 𝑅 × ran 𝑅))) | ||
Theorem | trclfv 15005* | The transitive closure of a relation. (Contributed by RP, 28-Apr-2020.) |
⊢ (𝑅 ∈ 𝑉 → (t+‘𝑅) = ∩ {𝑥 ∣ (𝑅 ⊆ 𝑥 ∧ (𝑥 ∘ 𝑥) ⊆ 𝑥)}) | ||
Theorem | brintclab 15006* | Two ways to express a binary relation which is the intersection of a class. (Contributed by RP, 4-Apr-2020.) |
⊢ (𝐴∩ {𝑥 ∣ 𝜑}𝐵 ↔ ∀𝑥(𝜑 → 〈𝐴, 𝐵〉 ∈ 𝑥)) | ||
Theorem | brtrclfv 15007* | Two ways of expressing the transitive closure of a binary relation. (Contributed by RP, 9-May-2020.) |
⊢ (𝑅 ∈ 𝑉 → (𝐴(t+‘𝑅)𝐵 ↔ ∀𝑟((𝑅 ⊆ 𝑟 ∧ (𝑟 ∘ 𝑟) ⊆ 𝑟) → 𝐴𝑟𝐵))) | ||
Theorem | brcnvtrclfv 15008* | Two ways of expressing the transitive closure of the converse of a binary relation. (Contributed by RP, 9-May-2020.) |
⊢ ((𝑅 ∈ 𝑈 ∧ 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → (𝐴◡(t+‘𝑅)𝐵 ↔ ∀𝑟((𝑅 ⊆ 𝑟 ∧ (𝑟 ∘ 𝑟) ⊆ 𝑟) → 𝐵𝑟𝐴))) | ||
Theorem | brtrclfvcnv 15009* | Two ways of expressing the transitive closure of the converse of a binary relation. (Contributed by RP, 10-May-2020.) |
⊢ (𝑅 ∈ 𝑉 → (𝐴(t+‘◡𝑅)𝐵 ↔ ∀𝑟((◡𝑅 ⊆ 𝑟 ∧ (𝑟 ∘ 𝑟) ⊆ 𝑟) → 𝐴𝑟𝐵))) | ||
Theorem | brcnvtrclfvcnv 15010* | Two ways of expressing the transitive closure of the converse of the converse of a binary relation. (Contributed by RP, 10-May-2020.) |
⊢ ((𝑅 ∈ 𝑈 ∧ 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊) → (𝐴◡(t+‘◡𝑅)𝐵 ↔ ∀𝑟((◡𝑅 ⊆ 𝑟 ∧ (𝑟 ∘ 𝑟) ⊆ 𝑟) → 𝐵𝑟𝐴))) | ||
Theorem | trclfvss 15011 | The transitive closure (as a relation) of a subclass is a subclass of the transitive closure. (Contributed by RP, 3-May-2020.) |
⊢ ((𝑅 ∈ 𝑉 ∧ 𝑆 ∈ 𝑊 ∧ 𝑅 ⊆ 𝑆) → (t+‘𝑅) ⊆ (t+‘𝑆)) | ||
Theorem | trclfvub 15012 | The transitive closure of a relation has an upper bound. (Contributed by RP, 28-Apr-2020.) |
⊢ (𝑅 ∈ 𝑉 → (t+‘𝑅) ⊆ (𝑅 ∪ (dom 𝑅 × ran 𝑅))) | ||
Theorem | trclfvlb 15013 | The transitive closure of a relation has a lower bound. (Contributed by RP, 28-Apr-2020.) |
⊢ (𝑅 ∈ 𝑉 → 𝑅 ⊆ (t+‘𝑅)) | ||
Theorem | trclfvcotr 15014 | The transitive closure of a relation is a transitive relation. (Contributed by RP, 29-Apr-2020.) |
⊢ (𝑅 ∈ 𝑉 → ((t+‘𝑅) ∘ (t+‘𝑅)) ⊆ (t+‘𝑅)) | ||
Theorem | trclfvlb2 15015 | The transitive closure of a relation has a lower bound. (Contributed by RP, 8-May-2020.) |
⊢ (𝑅 ∈ 𝑉 → (𝑅 ∘ 𝑅) ⊆ (t+‘𝑅)) | ||
Theorem | trclfvlb3 15016 | The transitive closure of a relation has a lower bound. (Contributed by RP, 8-May-2020.) |
⊢ (𝑅 ∈ 𝑉 → (𝑅 ∪ (𝑅 ∘ 𝑅)) ⊆ (t+‘𝑅)) | ||
Theorem | cotrtrclfv 15017 | The transitive closure of a transitive relation. (Contributed by RP, 28-Apr-2020.) |
⊢ ((𝑅 ∈ 𝑉 ∧ (𝑅 ∘ 𝑅) ⊆ 𝑅) → (t+‘𝑅) = 𝑅) | ||
Theorem | trclidm 15018 | The transitive closure of a relation is idempotent. (Contributed by RP, 29-Apr-2020.) |
⊢ (𝑅 ∈ 𝑉 → (t+‘(t+‘𝑅)) = (t+‘𝑅)) | ||
Theorem | trclun 15019 | Transitive closure of a union of relations. (Contributed by RP, 5-May-2020.) |
⊢ ((𝑅 ∈ 𝑉 ∧ 𝑆 ∈ 𝑊) → (t+‘(𝑅 ∪ 𝑆)) = (t+‘((t+‘𝑅) ∪ (t+‘𝑆)))) | ||
Theorem | trclfvg 15020 | The value of the transitive closure of a relation is a superset or (for proper classes) the empty set. (Contributed by RP, 8-May-2020.) |
⊢ (𝑅 ⊆ (t+‘𝑅) ∨ (t+‘𝑅) = ∅) | ||
Theorem | trclfvcotrg 15021 | The value of the transitive closure of a relation is always a transitive relation. (Contributed by RP, 8-May-2020.) |
⊢ ((t+‘𝑅) ∘ (t+‘𝑅)) ⊆ (t+‘𝑅) | ||
Theorem | reltrclfv 15022 | The transitive closure of a relation is a relation. (Contributed by RP, 9-May-2020.) |
⊢ ((𝑅 ∈ 𝑉 ∧ Rel 𝑅) → Rel (t+‘𝑅)) | ||
Theorem | dmtrclfv 15023 | The domain of the transitive closure is equal to the domain of the relation. (Contributed by RP, 9-May-2020.) |
⊢ (𝑅 ∈ 𝑉 → dom (t+‘𝑅) = dom 𝑅) | ||
Syntax | crelexp 15024 | Extend class notation to include relation exponentiation. |
class ↑𝑟 | ||
Definition | df-relexp 15025* | Definition of repeated composition of a relation with itself, aka relation exponentiation. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 22-May-2020.) |
⊢ ↑𝑟 = (𝑟 ∈ V, 𝑛 ∈ ℕ0 ↦ if(𝑛 = 0, ( I ↾ (dom 𝑟 ∪ ran 𝑟)), (seq1((𝑥 ∈ V, 𝑦 ∈ V ↦ (𝑥 ∘ 𝑟)), (𝑧 ∈ V ↦ 𝑟))‘𝑛))) | ||
Theorem | reldmrelexp 15026 | The domain of the repeated composition of a relation is a relation. (Contributed by AV, 12-Jul-2024.) |
⊢ Rel dom ↑𝑟 | ||
Theorem | relexp0g 15027 | A relation composed zero times is the (restricted) identity. (Contributed by RP, 22-May-2020.) |
⊢ (𝑅 ∈ 𝑉 → (𝑅↑𝑟0) = ( I ↾ (dom 𝑅 ∪ ran 𝑅))) | ||
Theorem | relexp0 15028 | A relation composed zero times is the (restricted) identity. (Contributed by RP, 22-May-2020.) |
⊢ ((𝑅 ∈ 𝑉 ∧ Rel 𝑅) → (𝑅↑𝑟0) = ( I ↾ ∪ ∪ 𝑅)) | ||
Theorem | relexp0d 15029 | A relation composed zero times is the (restricted) identity. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 12-Jul-2024.) |
⊢ (𝜑 → Rel 𝑅) & ⊢ (𝜑 → 𝑅 ∈ 𝑉) ⇒ ⊢ (𝜑 → (𝑅↑𝑟0) = ( I ↾ ∪ ∪ 𝑅)) | ||
Theorem | relexpsucnnr 15030 | A reduction for relation exponentiation to the right. (Contributed by RP, 22-May-2020.) |
⊢ ((𝑅 ∈ 𝑉 ∧ 𝑁 ∈ ℕ) → (𝑅↑𝑟(𝑁 + 1)) = ((𝑅↑𝑟𝑁) ∘ 𝑅)) | ||
Theorem | relexp1g 15031 | A relation composed once is itself. (Contributed by RP, 22-May-2020.) |
⊢ (𝑅 ∈ 𝑉 → (𝑅↑𝑟1) = 𝑅) | ||
Theorem | dfid5 15032 | Identity relation is equal to relational exponentiation to the first power. (Contributed by RP, 9-Jun-2020.) |
⊢ I = (𝑥 ∈ V ↦ (𝑥↑𝑟1)) | ||
Theorem | dfid6 15033* | Identity relation expressed as indexed union of relational powers. (Contributed by RP, 9-Jun-2020.) |
⊢ I = (𝑥 ∈ V ↦ ∪ 𝑛 ∈ {1} (𝑥↑𝑟𝑛)) | ||
Theorem | relexp1d 15034 | A relation composed once is itself. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 12-Jul-2024.) |
⊢ (𝜑 → 𝑅 ∈ 𝑉) ⇒ ⊢ (𝜑 → (𝑅↑𝑟1) = 𝑅) | ||
Theorem | relexpsucnnl 15035 | A reduction for relation exponentiation to the left. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑅 ∈ 𝑉 ∧ 𝑁 ∈ ℕ) → (𝑅↑𝑟(𝑁 + 1)) = (𝑅 ∘ (𝑅↑𝑟𝑁))) | ||
Theorem | relexpsucl 15036 | A reduction for relation exponentiation to the left. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑅 ∈ 𝑉 ∧ Rel 𝑅 ∧ 𝑁 ∈ ℕ0) → (𝑅↑𝑟(𝑁 + 1)) = (𝑅 ∘ (𝑅↑𝑟𝑁))) | ||
Theorem | relexpsucr 15037 | A reduction for relation exponentiation to the right. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑅 ∈ 𝑉 ∧ Rel 𝑅 ∧ 𝑁 ∈ ℕ0) → (𝑅↑𝑟(𝑁 + 1)) = ((𝑅↑𝑟𝑁) ∘ 𝑅)) | ||
Theorem | relexpsucrd 15038 | A reduction for relation exponentiation to the right. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 12-Jul-2024.) |
⊢ (𝜑 → Rel 𝑅) & ⊢ (𝜑 → 𝑁 ∈ ℕ0) ⇒ ⊢ (𝜑 → (𝑅↑𝑟(𝑁 + 1)) = ((𝑅↑𝑟𝑁) ∘ 𝑅)) | ||
Theorem | relexpsucld 15039 | A reduction for relation exponentiation to the left. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 12-Jul-2024.) |
⊢ (𝜑 → Rel 𝑅) & ⊢ (𝜑 → 𝑁 ∈ ℕ0) ⇒ ⊢ (𝜑 → (𝑅↑𝑟(𝑁 + 1)) = (𝑅 ∘ (𝑅↑𝑟𝑁))) | ||
Theorem | relexpcnv 15040 | Commutation of converse and relation exponentiation. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ ℕ0 ∧ 𝑅 ∈ 𝑉) → ◡(𝑅↑𝑟𝑁) = (◡𝑅↑𝑟𝑁)) | ||
Theorem | relexpcnvd 15041 | Commutation of converse and relation exponentiation. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 12-Jul-2024.) |
⊢ (𝜑 → 𝑅 ∈ 𝑉) & ⊢ (𝜑 → 𝑁 ∈ ℕ0) ⇒ ⊢ (𝜑 → ◡(𝑅↑𝑟𝑁) = (◡𝑅↑𝑟𝑁)) | ||
Theorem | relexp0rel 15042 | The exponentiation of a class to zero is a relation. (Contributed by RP, 23-May-2020.) |
⊢ (𝑅 ∈ 𝑉 → Rel (𝑅↑𝑟0)) | ||
Theorem | relexprelg 15043 | The exponentiation of a class is a relation except when the exponent is one and the class is not a relation. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ ℕ0 ∧ 𝑅 ∈ 𝑉 ∧ (𝑁 = 1 → Rel 𝑅)) → Rel (𝑅↑𝑟𝑁)) | ||
Theorem | relexprel 15044 | The exponentiation of a relation is a relation. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ ℕ0 ∧ 𝑅 ∈ 𝑉 ∧ Rel 𝑅) → Rel (𝑅↑𝑟𝑁)) | ||
Theorem | relexpreld 15045 | The exponentiation of a relation is a relation. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 12-Jul-2024.) |
⊢ (𝜑 → Rel 𝑅) & ⊢ (𝜑 → 𝑁 ∈ ℕ0) ⇒ ⊢ (𝜑 → Rel (𝑅↑𝑟𝑁)) | ||
Theorem | relexpnndm 15046 | The domain of an exponentiation of a relation a subset of the relation's field. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ ℕ ∧ 𝑅 ∈ 𝑉) → dom (𝑅↑𝑟𝑁) ⊆ dom 𝑅) | ||
Theorem | relexpdmg 15047 | The domain of an exponentiation of a relation a subset of the relation's field. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ ℕ0 ∧ 𝑅 ∈ 𝑉) → dom (𝑅↑𝑟𝑁) ⊆ (dom 𝑅 ∪ ran 𝑅)) | ||
Theorem | relexpdm 15048 | The domain of an exponentiation of a relation a subset of the relation's field. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ ℕ0 ∧ 𝑅 ∈ 𝑉) → dom (𝑅↑𝑟𝑁) ⊆ ∪ ∪ 𝑅) | ||
Theorem | relexpdmd 15049 | The domain of an exponentiation of a relation a subset of the relation's field. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 12-Jul-2024.) |
⊢ (𝜑 → 𝑁 ∈ ℕ0) ⇒ ⊢ (𝜑 → dom (𝑅↑𝑟𝑁) ⊆ ∪ ∪ 𝑅) | ||
Theorem | relexpnnrn 15050 | The range of an exponentiation of a relation a subset of the relation's field. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ ℕ ∧ 𝑅 ∈ 𝑉) → ran (𝑅↑𝑟𝑁) ⊆ ran 𝑅) | ||
Theorem | relexprng 15051 | The range of an exponentiation of a relation a subset of the relation's field. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ ℕ0 ∧ 𝑅 ∈ 𝑉) → ran (𝑅↑𝑟𝑁) ⊆ (dom 𝑅 ∪ ran 𝑅)) | ||
Theorem | relexprn 15052 | The range of an exponentiation of a relation a subset of the relation's field. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ ℕ0 ∧ 𝑅 ∈ 𝑉) → ran (𝑅↑𝑟𝑁) ⊆ ∪ ∪ 𝑅) | ||
Theorem | relexprnd 15053 | The range of an exponentiation of a relation a subset of the relation's field. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 12-Jul-2024.) |
⊢ (𝜑 → 𝑁 ∈ ℕ0) ⇒ ⊢ (𝜑 → ran (𝑅↑𝑟𝑁) ⊆ ∪ ∪ 𝑅) | ||
Theorem | relexpfld 15054 | The field of an exponentiation of a relation a subset of the relation's field. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ ℕ0 ∧ 𝑅 ∈ 𝑉) → ∪ ∪ (𝑅↑𝑟𝑁) ⊆ ∪ ∪ 𝑅) | ||
Theorem | relexpfldd 15055 | The field of an exponentiation of a relation a subset of the relation's field. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 12-Jul-2024.) |
⊢ (𝜑 → 𝑁 ∈ ℕ0) ⇒ ⊢ (𝜑 → ∪ ∪ (𝑅↑𝑟𝑁) ⊆ ∪ ∪ 𝑅) | ||
Theorem | relexpaddnn 15056 | Relation composition becomes addition under exponentiation. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ ℕ ∧ 𝑀 ∈ ℕ ∧ 𝑅 ∈ 𝑉) → ((𝑅↑𝑟𝑁) ∘ (𝑅↑𝑟𝑀)) = (𝑅↑𝑟(𝑁 + 𝑀))) | ||
Theorem | relexpuzrel 15057 | The exponentiation of a class to an integer not smaller than 2 is a relation. (Contributed by RP, 23-May-2020.) |
⊢ ((𝑁 ∈ (ℤ≥‘2) ∧ 𝑅 ∈ 𝑉) → Rel (𝑅↑𝑟𝑁)) | ||
Theorem | relexpaddg 15058 | Relation composition becomes addition under exponentiation except when the exponents total to one and the class isn't a relation. (Contributed by RP, 30-May-2020.) |
⊢ ((𝑁 ∈ ℕ0 ∧ (𝑀 ∈ ℕ0 ∧ 𝑅 ∈ 𝑉 ∧ ((𝑁 + 𝑀) = 1 → Rel 𝑅))) → ((𝑅↑𝑟𝑁) ∘ (𝑅↑𝑟𝑀)) = (𝑅↑𝑟(𝑁 + 𝑀))) | ||
Theorem | relexpaddd 15059 | Relation composition becomes addition under exponentiation. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 12-Jul-2024.) |
⊢ (𝜑 → Rel 𝑅) & ⊢ (𝜑 → 𝑁 ∈ ℕ0) & ⊢ (𝜑 → 𝑀 ∈ ℕ0) ⇒ ⊢ (𝜑 → ((𝑅↑𝑟𝑁) ∘ (𝑅↑𝑟𝑀)) = (𝑅↑𝑟(𝑁 + 𝑀))) | ||
Syntax | crtrcl 15060 | Extend class notation with recursively defined reflexive, transitive closure. |
class t*rec | ||
Definition | df-rtrclrec 15061* | The reflexive, transitive closure of a relation constructed as the union of all finite exponentiations. (Contributed by Drahflow, 12-Nov-2015.) |
⊢ t*rec = (𝑟 ∈ V ↦ ∪ 𝑛 ∈ ℕ0 (𝑟↑𝑟𝑛)) | ||
Theorem | rtrclreclem1 15062 | The reflexive, transitive closure is indeed a closure. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 12-Jul-2024.) |
⊢ (𝜑 → 𝑅 ∈ 𝑉) ⇒ ⊢ (𝜑 → 𝑅 ⊆ (t*rec‘𝑅)) | ||
Theorem | dfrtrclrec2 15063* | If two elements are connected by a reflexive, transitive closure, then they are connected via 𝑛 instances the relation, for some 𝑛. (Contributed by Drahflow, 12-Nov-2015.) (Revised by AV, 13-Jul-2024.) |
⊢ (𝜑 → Rel 𝑅) ⇒ ⊢ (𝜑 → (𝐴(t*rec‘𝑅)𝐵 ↔ ∃𝑛 ∈ ℕ0 𝐴(𝑅↑𝑟𝑛)𝐵)) | ||
Theorem | rtrclreclem2 15064 | The reflexive, transitive closure is indeed reflexive. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 13-Jul-2024.) |
⊢ (𝜑 → Rel 𝑅) & ⊢ (𝜑 → 𝑅 ∈ 𝑉) ⇒ ⊢ (𝜑 → ( I ↾ ∪ ∪ 𝑅) ⊆ (t*rec‘𝑅)) | ||
Theorem | rtrclreclem3 15065 | The reflexive, transitive closure is indeed transitive. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 13-Jul-2024.) |
⊢ (𝜑 → Rel 𝑅) ⇒ ⊢ (𝜑 → ((t*rec‘𝑅) ∘ (t*rec‘𝑅)) ⊆ (t*rec‘𝑅)) | ||
Theorem | rtrclreclem4 15066* | The reflexive, transitive closure of 𝑅 is the smallest reflexive, transitive relation which contains 𝑅 and the identity. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 13-Jul-2024.) |
⊢ (𝜑 → Rel 𝑅) ⇒ ⊢ (𝜑 → ∀𝑠((( I ↾ (dom 𝑅 ∪ ran 𝑅)) ⊆ 𝑠 ∧ 𝑅 ⊆ 𝑠 ∧ (𝑠 ∘ 𝑠) ⊆ 𝑠) → (t*rec‘𝑅) ⊆ 𝑠)) | ||
Theorem | dfrtrcl2 15067 | The two definitions t* and t*rec of the reflexive, transitive closure coincide if 𝑅 is indeed a relation. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 13-Jul-2024.) |
⊢ (𝜑 → Rel 𝑅) ⇒ ⊢ (𝜑 → (t*‘𝑅) = (t*rec‘𝑅)) | ||
If we have a statement that holds for some element, and a relation between elements that implies if it holds for the first element then it must hold for the second element, the principle of transitive induction shows the statement holds for any element related to the first by the (reflexive-)transitive closure of the relation. | ||
Theorem | relexpindlem 15068* | Principle of transitive induction, finite and non-class version. The first three hypotheses give various existences, the next three give necessary substitutions and the last two are the basis and the induction hypothesis. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Proof shortened by Peter Mazsa, 2-Oct-2022.) (Revised by AV, 13-Jul-2024.) |
⊢ (𝜂 → Rel 𝑅) & ⊢ (𝜂 → 𝑆 ∈ 𝑉) & ⊢ (𝑖 = 𝑆 → (𝜑 ↔ 𝜒)) & ⊢ (𝑖 = 𝑥 → (𝜑 ↔ 𝜓)) & ⊢ (𝑖 = 𝑗 → (𝜑 ↔ 𝜃)) & ⊢ (𝜂 → 𝜒) & ⊢ (𝜂 → (𝑗𝑅𝑥 → (𝜃 → 𝜓))) ⇒ ⊢ (𝜂 → (𝑛 ∈ ℕ0 → (𝑆(𝑅↑𝑟𝑛)𝑥 → 𝜓))) | ||
Theorem | relexpind 15069* | Principle of transitive induction, finite version. The first three hypotheses give various existences, the next four give necessary substitutions and the last two are the basis and the induction hypothesis. (Contributed by Drahflow, 12-Nov-2015.) (Revised by RP, 30-May-2020.) (Revised by AV, 13-Jul-2024.) |
⊢ (𝜂 → Rel 𝑅) & ⊢ (𝜂 → 𝑆 ∈ 𝑉) & ⊢ (𝜂 → 𝑋 ∈ 𝑊) & ⊢ (𝑖 = 𝑆 → (𝜑 ↔ 𝜒)) & ⊢ (𝑖 = 𝑥 → (𝜑 ↔ 𝜓)) & ⊢ (𝑖 = 𝑗 → (𝜑 ↔ 𝜃)) & ⊢ (𝑥 = 𝑋 → (𝜓 ↔ 𝜏)) & ⊢ (𝜂 → 𝜒) & ⊢ (𝜂 → (𝑗𝑅𝑥 → (𝜃 → 𝜓))) ⇒ ⊢ (𝜂 → (𝑛 ∈ ℕ0 → (𝑆(𝑅↑𝑟𝑛)𝑋 → 𝜏))) | ||
Theorem | rtrclind 15070* | Principle of transitive induction. The first three hypotheses give various existences, the next four give necessary substitutions and the last two are the basis and the induction step. (Contributed by Drahflow, 12-Nov-2015.) (Revised by AV, 13-Jul-2024.) |
⊢ (𝜂 → Rel 𝑅) & ⊢ (𝜂 → 𝑆 ∈ 𝑉) & ⊢ (𝜂 → 𝑋 ∈ 𝑊) & ⊢ (𝑖 = 𝑆 → (𝜑 ↔ 𝜒)) & ⊢ (𝑖 = 𝑥 → (𝜑 ↔ 𝜓)) & ⊢ (𝑖 = 𝑗 → (𝜑 ↔ 𝜃)) & ⊢ (𝑥 = 𝑋 → (𝜓 ↔ 𝜏)) & ⊢ (𝜂 → 𝜒) & ⊢ (𝜂 → (𝑗𝑅𝑥 → (𝜃 → 𝜓))) ⇒ ⊢ (𝜂 → (𝑆(t*‘𝑅)𝑋 → 𝜏)) | ||
Syntax | cshi 15071 | Extend class notation with function shifter. |
class shift | ||
Definition | df-shft 15072* | Define a function shifter. This operation offsets the value argument of a function (ordinarily on a subset of ℂ) and produces a new function on ℂ. See shftval 15079 for its value. (Contributed by NM, 20-Jul-2005.) |
⊢ shift = (𝑓 ∈ V, 𝑥 ∈ ℂ ↦ {〈𝑦, 𝑧〉 ∣ (𝑦 ∈ ℂ ∧ (𝑦 − 𝑥)𝑓𝑧)}) | ||
Theorem | shftlem 15073* | Two ways to write a shifted set (𝐵 + 𝐴). (Contributed by Mario Carneiro, 3-Nov-2013.) |
⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ⊆ ℂ) → {𝑥 ∈ ℂ ∣ (𝑥 − 𝐴) ∈ 𝐵} = {𝑥 ∣ ∃𝑦 ∈ 𝐵 𝑥 = (𝑦 + 𝐴)}) | ||
Theorem | shftuz 15074* | A shift of the upper integers. (Contributed by Mario Carneiro, 5-Nov-2013.) |
⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → {𝑥 ∈ ℂ ∣ (𝑥 − 𝐴) ∈ (ℤ≥‘𝐵)} = (ℤ≥‘(𝐵 + 𝐴))) | ||
Theorem | shftfval 15075* | The value of the sequence shifter operation is a function on ℂ. 𝐴 is ordinarily an integer. (Contributed by NM, 20-Jul-2005.) (Revised by Mario Carneiro, 3-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ (𝐴 ∈ ℂ → (𝐹 shift 𝐴) = {〈𝑥, 𝑦〉 ∣ (𝑥 ∈ ℂ ∧ (𝑥 − 𝐴)𝐹𝑦)}) | ||
Theorem | shftdm 15076* | Domain of a relation shifted by 𝐴. The set on the right is more commonly notated as (dom 𝐹 + 𝐴) (meaning add 𝐴 to every element of dom 𝐹). (Contributed by Mario Carneiro, 3-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ (𝐴 ∈ ℂ → dom (𝐹 shift 𝐴) = {𝑥 ∈ ℂ ∣ (𝑥 − 𝐴) ∈ dom 𝐹}) | ||
Theorem | shftfib 15077 | Value of a fiber of the relation 𝐹. (Contributed by Mario Carneiro, 4-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → ((𝐹 shift 𝐴) “ {𝐵}) = (𝐹 “ {(𝐵 − 𝐴)})) | ||
Theorem | shftfn 15078* | Functionality and domain of a sequence shifted by 𝐴. (Contributed by NM, 20-Jul-2005.) (Revised by Mario Carneiro, 3-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝐹 Fn 𝐵 ∧ 𝐴 ∈ ℂ) → (𝐹 shift 𝐴) Fn {𝑥 ∈ ℂ ∣ (𝑥 − 𝐴) ∈ 𝐵}) | ||
Theorem | shftval 15079 | Value of a sequence shifted by 𝐴. (Contributed by NM, 20-Jul-2005.) (Revised by Mario Carneiro, 4-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → ((𝐹 shift 𝐴)‘𝐵) = (𝐹‘(𝐵 − 𝐴))) | ||
Theorem | shftval2 15080 | Value of a sequence shifted by 𝐴 − 𝐵. (Contributed by NM, 20-Jul-2005.) (Revised by Mario Carneiro, 5-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ∧ 𝐶 ∈ ℂ) → ((𝐹 shift (𝐴 − 𝐵))‘(𝐴 + 𝐶)) = (𝐹‘(𝐵 + 𝐶))) | ||
Theorem | shftval3 15081 | Value of a sequence shifted by 𝐴 − 𝐵. (Contributed by NM, 20-Jul-2005.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → ((𝐹 shift (𝐴 − 𝐵))‘𝐴) = (𝐹‘𝐵)) | ||
Theorem | shftval4 15082 | Value of a sequence shifted by -𝐴. (Contributed by NM, 18-Aug-2005.) (Revised by Mario Carneiro, 5-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → ((𝐹 shift -𝐴)‘𝐵) = (𝐹‘(𝐴 + 𝐵))) | ||
Theorem | shftval5 15083 | Value of a shifted sequence. (Contributed by NM, 19-Aug-2005.) (Revised by Mario Carneiro, 5-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → ((𝐹 shift 𝐴)‘(𝐵 + 𝐴)) = (𝐹‘𝐵)) | ||
Theorem | shftf 15084* | Functionality of a shifted sequence. (Contributed by NM, 19-Aug-2005.) (Revised by Mario Carneiro, 5-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝐹:𝐵⟶𝐶 ∧ 𝐴 ∈ ℂ) → (𝐹 shift 𝐴):{𝑥 ∈ ℂ ∣ (𝑥 − 𝐴) ∈ 𝐵}⟶𝐶) | ||
Theorem | 2shfti 15085 | Composite shift operations. (Contributed by NM, 19-Aug-2005.) (Revised by Mario Carneiro, 5-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → ((𝐹 shift 𝐴) shift 𝐵) = (𝐹 shift (𝐴 + 𝐵))) | ||
Theorem | shftidt2 15086 | Identity law for the shift operation. (Contributed by Mario Carneiro, 5-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ (𝐹 shift 0) = (𝐹 ↾ ℂ) | ||
Theorem | shftidt 15087 | Identity law for the shift operation. (Contributed by NM, 19-Aug-2005.) (Revised by Mario Carneiro, 5-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ (𝐴 ∈ ℂ → ((𝐹 shift 0)‘𝐴) = (𝐹‘𝐴)) | ||
Theorem | shftcan1 15088 | Cancellation law for the shift operation. (Contributed by NM, 4-Aug-2005.) (Revised by Mario Carneiro, 5-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → (((𝐹 shift 𝐴) shift -𝐴)‘𝐵) = (𝐹‘𝐵)) | ||
Theorem | shftcan2 15089 | Cancellation law for the shift operation. (Contributed by NM, 4-Aug-2005.) (Revised by Mario Carneiro, 5-Nov-2013.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → (((𝐹 shift -𝐴) shift 𝐴)‘𝐵) = (𝐹‘𝐵)) | ||
Theorem | seqshft 15090 | Shifting the index set of a sequence. (Contributed by NM, 17-Mar-2005.) (Revised by Mario Carneiro, 27-Feb-2014.) |
⊢ 𝐹 ∈ V ⇒ ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → seq𝑀( + , (𝐹 shift 𝑁)) = (seq(𝑀 − 𝑁)( + , 𝐹) shift 𝑁)) | ||
Syntax | csgn 15091 | Extend class notation to include the Signum function. |
class sgn | ||
Definition | df-sgn 15092 | Signum function. We do not call it "sign", which is homophonic with "sine" (df-sin 16071). Defined as "sgn" in ISO 80000-2:2009(E) operation 2-9.13. It is named "sign" (with the same definition) in the "NIST Digital Library of Mathematical Functions" , front introduction, "Common Notations and Definitions" section at http://dlmf.nist.gov/front/introduction#Sx4 16071. We define this over ℝ* (df-xr 11302) instead of ℝ so that it can accept +∞ and -∞. Note that df-psgn 19489 defines the sign of a permutation, which is different. Value shown in sgnval 15093. (Contributed by David A. Wheeler, 15-May-2015.) |
⊢ sgn = (𝑥 ∈ ℝ* ↦ if(𝑥 = 0, 0, if(𝑥 < 0, -1, 1))) | ||
Theorem | sgnval 15093 | Value of the signum function. (Contributed by David A. Wheeler, 15-May-2015.) |
⊢ (𝐴 ∈ ℝ* → (sgn‘𝐴) = if(𝐴 = 0, 0, if(𝐴 < 0, -1, 1))) | ||
Theorem | sgn0 15094 | The signum of 0 is 0. (Contributed by David A. Wheeler, 15-May-2015.) |
⊢ (sgn‘0) = 0 | ||
Theorem | sgnp 15095 | The signum of a positive extended real is 1. (Contributed by David A. Wheeler, 15-May-2015.) |
⊢ ((𝐴 ∈ ℝ* ∧ 0 < 𝐴) → (sgn‘𝐴) = 1) | ||
Theorem | sgnrrp 15096 | The signum of a positive real is 1. (Contributed by David A. Wheeler, 18-May-2015.) |
⊢ (𝐴 ∈ ℝ+ → (sgn‘𝐴) = 1) | ||
Theorem | sgn1 15097 | The signum of 1 is 1. (Contributed by David A. Wheeler, 26-Jun-2016.) |
⊢ (sgn‘1) = 1 | ||
Theorem | sgnpnf 15098 | The signum of +∞ is 1. (Contributed by David A. Wheeler, 26-Jun-2016.) |
⊢ (sgn‘+∞) = 1 | ||
Theorem | sgnn 15099 | The signum of a negative extended real is -1. (Contributed by David A. Wheeler, 15-May-2015.) |
⊢ ((𝐴 ∈ ℝ* ∧ 𝐴 < 0) → (sgn‘𝐴) = -1) | ||
Theorem | sgnmnf 15100 | The signum of -∞ is -1. (Contributed by David A. Wheeler, 26-Jun-2016.) |
⊢ (sgn‘-∞) = -1 |
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