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Type | Label | Description |
---|---|---|
Statement | ||
Theorem | isocnv2 6901 | Converse law for isomorphism. (Contributed by Mario Carneiro, 30-Jan-2014.) |
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ↔ 𝐻 Isom ◡𝑅, ◡𝑆(𝐴, 𝐵)) | ||
Theorem | isocnv3 6902 | Complementation law for isomorphism. (Contributed by Mario Carneiro, 9-Sep-2015.) |
⊢ 𝐶 = ((𝐴 × 𝐴) ∖ 𝑅) & ⊢ 𝐷 = ((𝐵 × 𝐵) ∖ 𝑆) ⇒ ⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ↔ 𝐻 Isom 𝐶, 𝐷 (𝐴, 𝐵)) | ||
Theorem | isores2 6903 | An isomorphism from one well-order to another can be restricted on either well-order. (Contributed by Mario Carneiro, 15-Jan-2013.) |
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ↔ 𝐻 Isom 𝑅, (𝑆 ∩ (𝐵 × 𝐵))(𝐴, 𝐵)) | ||
Theorem | isores1 6904 | An isomorphism from one well-order to another can be restricted on either well-order. (Contributed by Mario Carneiro, 15-Jan-2013.) |
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ↔ 𝐻 Isom (𝑅 ∩ (𝐴 × 𝐴)), 𝑆(𝐴, 𝐵)) | ||
Theorem | isores3 6905 | Induced isomorphism on a subset. (Contributed by Stefan O'Rear, 5-Nov-2014.) |
⊢ ((𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ∧ 𝐾 ⊆ 𝐴 ∧ 𝑋 = (𝐻 “ 𝐾)) → (𝐻 ↾ 𝐾) Isom 𝑅, 𝑆 (𝐾, 𝑋)) | ||
Theorem | isotr 6906 | Composition (transitive) law for isomorphism. Proposition 6.30(3) of [TakeutiZaring] p. 33. (Contributed by NM, 27-Apr-2004.) (Proof shortened by Mario Carneiro, 5-Dec-2016.) |
⊢ ((𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ∧ 𝐺 Isom 𝑆, 𝑇 (𝐵, 𝐶)) → (𝐺 ∘ 𝐻) Isom 𝑅, 𝑇 (𝐴, 𝐶)) | ||
Theorem | isomin 6907 | Isomorphisms preserve minimal elements. Note that (◡𝑅 “ {𝐷}) is Takeuti and Zaring's idiom for the initial segment {𝑥 ∣ 𝑥𝑅𝐷}. Proposition 6.31(1) of [TakeutiZaring] p. 33. (Contributed by NM, 19-Apr-2004.) |
⊢ ((𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ∧ (𝐶 ⊆ 𝐴 ∧ 𝐷 ∈ 𝐴)) → ((𝐶 ∩ (◡𝑅 “ {𝐷})) = ∅ ↔ ((𝐻 “ 𝐶) ∩ (◡𝑆 “ {(𝐻‘𝐷)})) = ∅)) | ||
Theorem | isoini 6908 | Isomorphisms preserve initial segments. Proposition 6.31(2) of [TakeutiZaring] p. 33. (Contributed by NM, 20-Apr-2004.) |
⊢ ((𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ∧ 𝐷 ∈ 𝐴) → (𝐻 “ (𝐴 ∩ (◡𝑅 “ {𝐷}))) = (𝐵 ∩ (◡𝑆 “ {(𝐻‘𝐷)}))) | ||
Theorem | isoini2 6909 | Isomorphisms are isomorphisms on their initial segments. (Contributed by Mario Carneiro, 29-Mar-2014.) |
⊢ 𝐶 = (𝐴 ∩ (◡𝑅 “ {𝑋})) & ⊢ 𝐷 = (𝐵 ∩ (◡𝑆 “ {(𝐻‘𝑋)})) ⇒ ⊢ ((𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ∧ 𝑋 ∈ 𝐴) → (𝐻 ↾ 𝐶) Isom 𝑅, 𝑆 (𝐶, 𝐷)) | ||
Theorem | isofrlem 6910* | Lemma for isofr 6912. (Contributed by NM, 29-Apr-2004.) (Revised by Mario Carneiro, 18-Nov-2014.) |
⊢ (𝜑 → 𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵)) & ⊢ (𝜑 → (𝐻 “ 𝑥) ∈ V) ⇒ ⊢ (𝜑 → (𝑆 Fr 𝐵 → 𝑅 Fr 𝐴)) | ||
Theorem | isoselem 6911* | Lemma for isose 6913. (Contributed by Mario Carneiro, 23-Jun-2015.) |
⊢ (𝜑 → 𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵)) & ⊢ (𝜑 → (𝐻 “ 𝑥) ∈ V) ⇒ ⊢ (𝜑 → (𝑅 Se 𝐴 → 𝑆 Se 𝐵)) | ||
Theorem | isofr 6912 | An isomorphism preserves well-foundedness. Proposition 6.32(1) of [TakeutiZaring] p. 33. (Contributed by NM, 30-Apr-2004.) (Revised by Mario Carneiro, 18-Nov-2014.) |
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) → (𝑅 Fr 𝐴 ↔ 𝑆 Fr 𝐵)) | ||
Theorem | isose 6913 | An isomorphism preserves set-like relations. (Contributed by Mario Carneiro, 23-Jun-2015.) |
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) → (𝑅 Se 𝐴 ↔ 𝑆 Se 𝐵)) | ||
Theorem | isofr2 6914 | A weak form of isofr 6912 that does not need Replacement. (Contributed by Mario Carneiro, 18-Nov-2014.) |
⊢ ((𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ∧ 𝐵 ∈ 𝑉) → (𝑆 Fr 𝐵 → 𝑅 Fr 𝐴)) | ||
Theorem | isopolem 6915 | Lemma for isopo 6916. (Contributed by Stefan O'Rear, 16-Nov-2014.) |
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) → (𝑆 Po 𝐵 → 𝑅 Po 𝐴)) | ||
Theorem | isopo 6916 | An isomorphism preserves partial ordering. (Contributed by Stefan O'Rear, 16-Nov-2014.) |
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) → (𝑅 Po 𝐴 ↔ 𝑆 Po 𝐵)) | ||
Theorem | isosolem 6917 | Lemma for isoso 6918. (Contributed by Stefan O'Rear, 16-Nov-2014.) |
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) → (𝑆 Or 𝐵 → 𝑅 Or 𝐴)) | ||
Theorem | isoso 6918 | An isomorphism preserves strict ordering. (Contributed by Stefan O'Rear, 16-Nov-2014.) |
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) → (𝑅 Or 𝐴 ↔ 𝑆 Or 𝐵)) | ||
Theorem | isowe 6919 | An isomorphism preserves well-ordering. Proposition 6.32(3) of [TakeutiZaring] p. 33. (Contributed by NM, 30-Apr-2004.) (Revised by Mario Carneiro, 18-Nov-2014.) |
⊢ (𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) → (𝑅 We 𝐴 ↔ 𝑆 We 𝐵)) | ||
Theorem | isowe2 6920* | A weak form of isowe 6919 that does not need Replacement. (Contributed by Mario Carneiro, 18-Nov-2014.) |
⊢ ((𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵) ∧ ∀𝑥(𝐻 “ 𝑥) ∈ V) → (𝑆 We 𝐵 → 𝑅 We 𝐴)) | ||
Theorem | f1oiso 6921* | Any one-to-one onto function determines an isomorphism with an induced relation 𝑆. Proposition 6.33 of [TakeutiZaring] p. 34. (Contributed by NM, 30-Apr-2004.) |
⊢ ((𝐻:𝐴–1-1-onto→𝐵 ∧ 𝑆 = {〈𝑧, 𝑤〉 ∣ ∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐴 ((𝑧 = (𝐻‘𝑥) ∧ 𝑤 = (𝐻‘𝑦)) ∧ 𝑥𝑅𝑦)}) → 𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵)) | ||
Theorem | f1oiso2 6922* | Any one-to-one onto function determines an isomorphism with an induced relation 𝑆. (Contributed by Mario Carneiro, 9-Mar-2013.) |
⊢ 𝑆 = {〈𝑥, 𝑦〉 ∣ ((𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵) ∧ (◡𝐻‘𝑥)𝑅(◡𝐻‘𝑦))} ⇒ ⊢ (𝐻:𝐴–1-1-onto→𝐵 → 𝐻 Isom 𝑅, 𝑆 (𝐴, 𝐵)) | ||
Theorem | f1owe 6923* | Well-ordering of isomorphic relations. (Contributed by NM, 4-Mar-1997.) |
⊢ 𝑅 = {〈𝑥, 𝑦〉 ∣ (𝐹‘𝑥)𝑆(𝐹‘𝑦)} ⇒ ⊢ (𝐹:𝐴–1-1-onto→𝐵 → (𝑆 We 𝐵 → 𝑅 We 𝐴)) | ||
Theorem | weniso 6924 | A set-like well-ordering has no nontrivial automorphisms. (Contributed by Stefan O'Rear, 16-Nov-2014.) (Revised by Mario Carneiro, 25-Jun-2015.) |
⊢ ((𝑅 We 𝐴 ∧ 𝑅 Se 𝐴 ∧ 𝐹 Isom 𝑅, 𝑅 (𝐴, 𝐴)) → 𝐹 = ( I ↾ 𝐴)) | ||
Theorem | weisoeq 6925 | Thus, there is at most one isomorphism between any two set-like well-ordered classes. Class version of wemoiso 7480. (Contributed by Mario Carneiro, 25-Jun-2015.) |
⊢ (((𝑅 We 𝐴 ∧ 𝑅 Se 𝐴) ∧ (𝐹 Isom 𝑅, 𝑆 (𝐴, 𝐵) ∧ 𝐺 Isom 𝑅, 𝑆 (𝐴, 𝐵))) → 𝐹 = 𝐺) | ||
Theorem | weisoeq2 6926 | Thus, there is at most one isomorphism between any two set-like well-ordered classes. Class version of wemoiso2 7481. (Contributed by Mario Carneiro, 25-Jun-2015.) |
⊢ (((𝑆 We 𝐵 ∧ 𝑆 Se 𝐵) ∧ (𝐹 Isom 𝑅, 𝑆 (𝐴, 𝐵) ∧ 𝐺 Isom 𝑅, 𝑆 (𝐴, 𝐵))) → 𝐹 = 𝐺) | ||
Theorem | knatar 6927* | The Knaster-Tarski theorem says that every monotone function over a complete lattice has a (least) fixpoint. Here we specialize this theorem to the case when the lattice is the powerset lattice 𝒫 𝐴. (Contributed by Mario Carneiro, 11-Jun-2015.) |
⊢ 𝑋 = ∩ {𝑧 ∈ 𝒫 𝐴 ∣ (𝐹‘𝑧) ⊆ 𝑧} ⇒ ⊢ ((𝐴 ∈ 𝑉 ∧ (𝐹‘𝐴) ⊆ 𝐴 ∧ ∀𝑥 ∈ 𝒫 𝐴∀𝑦 ∈ 𝒫 𝑥(𝐹‘𝑦) ⊆ (𝐹‘𝑥)) → (𝑋 ⊆ 𝐴 ∧ (𝐹‘𝑋) = 𝑋)) | ||
Theorem | canth 6928 | No set 𝐴 is equinumerous to its power set (Cantor's theorem), i.e. no function can map 𝐴 it onto its power set. Compare Theorem 6B(b) of [Enderton] p. 132. For the equinumerosity version, see canth2 8460. Note that 𝐴 must be a set: this theorem does not hold when 𝐴 is too large to be a set; see ncanth 6929 for a counterexample. (Use nex 1763 if you want the form ¬ ∃𝑓𝑓:𝐴–onto→𝒫 𝐴.) (Contributed by NM, 7-Aug-1994.) (Proof shortened by Mario Carneiro, 7-Jun-2016.) |
⊢ 𝐴 ∈ V ⇒ ⊢ ¬ 𝐹:𝐴–onto→𝒫 𝐴 | ||
Theorem | ncanth 6929 | Cantor's theorem fails for the universal class (which is not a set but a proper class by vprc 5070). Specifically, the identity function maps the universe onto its power class. Compare canth 6928 that works for sets. See also the remark in ru 3674 about NF, in which Cantor's theorem fails for sets that are "too large." This theorem gives some intuition behind that failure: in NF the universal class is a set, and it equals its own power set. (Contributed by NM, 29-Jun-2004.) |
⊢ I :V–onto→𝒫 V | ||
Syntax | crio 6930 | Extend class notation with restricted description binder. |
class (℩𝑥 ∈ 𝐴 𝜑) | ||
Definition | df-riota 6931 | Define restricted description binder. In case there is no unique 𝑥 such that (𝑥 ∈ 𝐴 ∧ 𝜑) holds, it evaluates to the empty set. See also comments for df-iota 6146. (Contributed by NM, 15-Sep-2011.) (Revised by Mario Carneiro, 15-Oct-2016.) (Revised by NM, 2-Sep-2018.) |
⊢ (℩𝑥 ∈ 𝐴 𝜑) = (℩𝑥(𝑥 ∈ 𝐴 ∧ 𝜑)) | ||
Theorem | riotaeqdv 6932* | Formula-building deduction for iota. (Contributed by NM, 15-Sep-2011.) |
⊢ (𝜑 → 𝐴 = 𝐵) ⇒ ⊢ (𝜑 → (℩𝑥 ∈ 𝐴 𝜓) = (℩𝑥 ∈ 𝐵 𝜓)) | ||
Theorem | riotabidv 6933* | Formula-building deduction for restricted iota. (Contributed by NM, 15-Sep-2011.) |
⊢ (𝜑 → (𝜓 ↔ 𝜒)) ⇒ ⊢ (𝜑 → (℩𝑥 ∈ 𝐴 𝜓) = (℩𝑥 ∈ 𝐴 𝜒)) | ||
Theorem | riotaeqbidv 6934* | Equality deduction for restricted universal quantifier. (Contributed by NM, 15-Sep-2011.) |
⊢ (𝜑 → 𝐴 = 𝐵) & ⊢ (𝜑 → (𝜓 ↔ 𝜒)) ⇒ ⊢ (𝜑 → (℩𝑥 ∈ 𝐴 𝜓) = (℩𝑥 ∈ 𝐵 𝜒)) | ||
Theorem | riotaex 6935 | Restricted iota is a set. (Contributed by NM, 15-Sep-2011.) |
⊢ (℩𝑥 ∈ 𝐴 𝜓) ∈ V | ||
Theorem | riotav 6936 | An iota restricted to the universe is unrestricted. (Contributed by NM, 18-Sep-2011.) |
⊢ (℩𝑥 ∈ V 𝜑) = (℩𝑥𝜑) | ||
Theorem | riotauni 6937 | Restricted iota in terms of class union. (Contributed by NM, 11-Oct-2011.) |
⊢ (∃!𝑥 ∈ 𝐴 𝜑 → (℩𝑥 ∈ 𝐴 𝜑) = ∪ {𝑥 ∈ 𝐴 ∣ 𝜑}) | ||
Theorem | nfriota1 6938* | The abstraction variable in a restricted iota descriptor isn't free. (Contributed by NM, 12-Oct-2011.) (Revised by Mario Carneiro, 15-Oct-2016.) |
⊢ Ⅎ𝑥(℩𝑥 ∈ 𝐴 𝜑) | ||
Theorem | nfriotad 6939 | Deduction version of nfriota 6940. (Contributed by NM, 18-Feb-2013.) (Revised by Mario Carneiro, 15-Oct-2016.) |
⊢ Ⅎ𝑦𝜑 & ⊢ (𝜑 → Ⅎ𝑥𝜓) & ⊢ (𝜑 → Ⅎ𝑥𝐴) ⇒ ⊢ (𝜑 → Ⅎ𝑥(℩𝑦 ∈ 𝐴 𝜓)) | ||
Theorem | nfriota 6940* | A variable not free in a wff remains so in a restricted iota descriptor. (Contributed by NM, 12-Oct-2011.) |
⊢ Ⅎ𝑥𝜑 & ⊢ Ⅎ𝑥𝐴 ⇒ ⊢ Ⅎ𝑥(℩𝑦 ∈ 𝐴 𝜑) | ||
Theorem | cbvriota 6941* | Change bound variable in a restricted description binder. (Contributed by NM, 18-Mar-2013.) (Revised by Mario Carneiro, 15-Oct-2016.) |
⊢ Ⅎ𝑦𝜑 & ⊢ Ⅎ𝑥𝜓 & ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) ⇒ ⊢ (℩𝑥 ∈ 𝐴 𝜑) = (℩𝑦 ∈ 𝐴 𝜓) | ||
Theorem | cbvriotav 6942* | Change bound variable in a restricted description binder. (Contributed by NM, 18-Mar-2013.) (Revised by Mario Carneiro, 15-Oct-2016.) |
⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) ⇒ ⊢ (℩𝑥 ∈ 𝐴 𝜑) = (℩𝑦 ∈ 𝐴 𝜓) | ||
Theorem | csbriota 6943* | Interchange class substitution and restricted description binder. (Contributed by NM, 24-Feb-2013.) (Revised by NM, 2-Sep-2018.) |
⊢ ⦋𝐴 / 𝑥⦌(℩𝑦 ∈ 𝐵 𝜑) = (℩𝑦 ∈ 𝐵 [𝐴 / 𝑥]𝜑) | ||
Theorem | riotacl2 6944 | Membership law for "the unique element in 𝐴 such that 𝜑". (Contributed by NM, 21-Aug-2011.) (Revised by Mario Carneiro, 23-Dec-2016.) |
⊢ (∃!𝑥 ∈ 𝐴 𝜑 → (℩𝑥 ∈ 𝐴 𝜑) ∈ {𝑥 ∈ 𝐴 ∣ 𝜑}) | ||
Theorem | riotacl 6945* | Closure of restricted iota. (Contributed by NM, 21-Aug-2011.) |
⊢ (∃!𝑥 ∈ 𝐴 𝜑 → (℩𝑥 ∈ 𝐴 𝜑) ∈ 𝐴) | ||
Theorem | riotasbc 6946 | Substitution law for descriptions. Compare iotasbc 40168. (Contributed by NM, 23-Aug-2011.) (Proof shortened by Mario Carneiro, 24-Dec-2016.) |
⊢ (∃!𝑥 ∈ 𝐴 𝜑 → [(℩𝑥 ∈ 𝐴 𝜑) / 𝑥]𝜑) | ||
Theorem | riotabidva 6947* | Equivalent wff's yield equal restricted class abstractions (deduction form). (rabbidva 3396 analog.) (Contributed by NM, 17-Jan-2012.) |
⊢ ((𝜑 ∧ 𝑥 ∈ 𝐴) → (𝜓 ↔ 𝜒)) ⇒ ⊢ (𝜑 → (℩𝑥 ∈ 𝐴 𝜓) = (℩𝑥 ∈ 𝐴 𝜒)) | ||
Theorem | riotabiia 6948 | Equivalent wff's yield equal restricted iotas (inference form). (rabbiia 3392 analog.) (Contributed by NM, 16-Jan-2012.) |
⊢ (𝑥 ∈ 𝐴 → (𝜑 ↔ 𝜓)) ⇒ ⊢ (℩𝑥 ∈ 𝐴 𝜑) = (℩𝑥 ∈ 𝐴 𝜓) | ||
Theorem | riota1 6949* | Property of restricted iota. Compare iota1 6160. (Contributed by Mario Carneiro, 15-Oct-2016.) |
⊢ (∃!𝑥 ∈ 𝐴 𝜑 → ((𝑥 ∈ 𝐴 ∧ 𝜑) ↔ (℩𝑥 ∈ 𝐴 𝜑) = 𝑥)) | ||
Theorem | riota1a 6950 | Property of iota. (Contributed by NM, 23-Aug-2011.) |
⊢ ((𝑥 ∈ 𝐴 ∧ ∃!𝑥 ∈ 𝐴 𝜑) → (𝜑 ↔ (℩𝑥(𝑥 ∈ 𝐴 ∧ 𝜑)) = 𝑥)) | ||
Theorem | riota2df 6951* | A deduction version of riota2f 6952. (Contributed by NM, 17-Feb-2013.) (Revised by Mario Carneiro, 15-Oct-2016.) |
⊢ Ⅎ𝑥𝜑 & ⊢ (𝜑 → Ⅎ𝑥𝐵) & ⊢ (𝜑 → Ⅎ𝑥𝜒) & ⊢ (𝜑 → 𝐵 ∈ 𝐴) & ⊢ ((𝜑 ∧ 𝑥 = 𝐵) → (𝜓 ↔ 𝜒)) ⇒ ⊢ ((𝜑 ∧ ∃!𝑥 ∈ 𝐴 𝜓) → (𝜒 ↔ (℩𝑥 ∈ 𝐴 𝜓) = 𝐵)) | ||
Theorem | riota2f 6952* | This theorem shows a condition that allows us to represent a descriptor with a class expression 𝐵. (Contributed by NM, 23-Aug-2011.) (Revised by Mario Carneiro, 15-Oct-2016.) |
⊢ Ⅎ𝑥𝐵 & ⊢ Ⅎ𝑥𝜓 & ⊢ (𝑥 = 𝐵 → (𝜑 ↔ 𝜓)) ⇒ ⊢ ((𝐵 ∈ 𝐴 ∧ ∃!𝑥 ∈ 𝐴 𝜑) → (𝜓 ↔ (℩𝑥 ∈ 𝐴 𝜑) = 𝐵)) | ||
Theorem | riota2 6953* | This theorem shows a condition that allows us to represent a descriptor with a class expression 𝐵. (Contributed by NM, 23-Aug-2011.) (Revised by Mario Carneiro, 10-Dec-2016.) |
⊢ (𝑥 = 𝐵 → (𝜑 ↔ 𝜓)) ⇒ ⊢ ((𝐵 ∈ 𝐴 ∧ ∃!𝑥 ∈ 𝐴 𝜑) → (𝜓 ↔ (℩𝑥 ∈ 𝐴 𝜑) = 𝐵)) | ||
Theorem | riotaeqimp 6954* | If two restricted iota descriptors for an equality are equal, then the terms of the equality are equal. (Contributed by AV, 6-Dec-2020.) |
⊢ 𝐼 = (℩𝑎 ∈ 𝑉 𝑋 = 𝐴) & ⊢ 𝐽 = (℩𝑎 ∈ 𝑉 𝑌 = 𝐴) & ⊢ (𝜑 → ∃!𝑎 ∈ 𝑉 𝑋 = 𝐴) & ⊢ (𝜑 → ∃!𝑎 ∈ 𝑉 𝑌 = 𝐴) ⇒ ⊢ ((𝜑 ∧ 𝐼 = 𝐽) → 𝑋 = 𝑌) | ||
Theorem | riotaprop 6955* | Properties of a restricted definite description operator. (Contributed by NM, 23-Nov-2013.) |
⊢ Ⅎ𝑥𝜓 & ⊢ 𝐵 = (℩𝑥 ∈ 𝐴 𝜑) & ⊢ (𝑥 = 𝐵 → (𝜑 ↔ 𝜓)) ⇒ ⊢ (∃!𝑥 ∈ 𝐴 𝜑 → (𝐵 ∈ 𝐴 ∧ 𝜓)) | ||
Theorem | riota5f 6956* | A method for computing restricted iota. (Contributed by NM, 16-Apr-2013.) (Revised by Mario Carneiro, 15-Oct-2016.) |
⊢ (𝜑 → Ⅎ𝑥𝐵) & ⊢ (𝜑 → 𝐵 ∈ 𝐴) & ⊢ ((𝜑 ∧ 𝑥 ∈ 𝐴) → (𝜓 ↔ 𝑥 = 𝐵)) ⇒ ⊢ (𝜑 → (℩𝑥 ∈ 𝐴 𝜓) = 𝐵) | ||
Theorem | riota5 6957* | A method for computing restricted iota. (Contributed by NM, 20-Oct-2011.) (Revised by Mario Carneiro, 6-Dec-2016.) |
⊢ (𝜑 → 𝐵 ∈ 𝐴) & ⊢ ((𝜑 ∧ 𝑥 ∈ 𝐴) → (𝜓 ↔ 𝑥 = 𝐵)) ⇒ ⊢ (𝜑 → (℩𝑥 ∈ 𝐴 𝜓) = 𝐵) | ||
Theorem | riotass2 6958* | Restriction of a unique element to a smaller class. (Contributed by NM, 21-Aug-2011.) (Revised by NM, 22-Mar-2013.) |
⊢ (((𝐴 ⊆ 𝐵 ∧ ∀𝑥 ∈ 𝐴 (𝜑 → 𝜓)) ∧ (∃𝑥 ∈ 𝐴 𝜑 ∧ ∃!𝑥 ∈ 𝐵 𝜓)) → (℩𝑥 ∈ 𝐴 𝜑) = (℩𝑥 ∈ 𝐵 𝜓)) | ||
Theorem | riotass 6959* | Restriction of a unique element to a smaller class. (Contributed by NM, 19-Oct-2005.) (Revised by Mario Carneiro, 24-Dec-2016.) |
⊢ ((𝐴 ⊆ 𝐵 ∧ ∃𝑥 ∈ 𝐴 𝜑 ∧ ∃!𝑥 ∈ 𝐵 𝜑) → (℩𝑥 ∈ 𝐴 𝜑) = (℩𝑥 ∈ 𝐵 𝜑)) | ||
Theorem | moriotass 6960* | Restriction of a unique element to a smaller class. (Contributed by NM, 19-Feb-2006.) (Revised by NM, 16-Jun-2017.) |
⊢ ((𝐴 ⊆ 𝐵 ∧ ∃𝑥 ∈ 𝐴 𝜑 ∧ ∃*𝑥 ∈ 𝐵 𝜑) → (℩𝑥 ∈ 𝐴 𝜑) = (℩𝑥 ∈ 𝐵 𝜑)) | ||
Theorem | snriota 6961 | A restricted class abstraction with a unique member can be expressed as a singleton. (Contributed by NM, 30-May-2006.) |
⊢ (∃!𝑥 ∈ 𝐴 𝜑 → {𝑥 ∈ 𝐴 ∣ 𝜑} = {(℩𝑥 ∈ 𝐴 𝜑)}) | ||
Theorem | riotaxfrd 6962* | Change the variable 𝑥 in the expression for "the unique 𝑥 such that 𝜓 " to another variable 𝑦 contained in expression 𝐵. Use reuhypd 5170 to eliminate the last hypothesis. (Contributed by NM, 16-Jan-2012.) (Revised by Mario Carneiro, 15-Oct-2016.) |
⊢ Ⅎ𝑦𝐶 & ⊢ ((𝜑 ∧ 𝑦 ∈ 𝐴) → 𝐵 ∈ 𝐴) & ⊢ ((𝜑 ∧ (℩𝑦 ∈ 𝐴 𝜒) ∈ 𝐴) → 𝐶 ∈ 𝐴) & ⊢ (𝑥 = 𝐵 → (𝜓 ↔ 𝜒)) & ⊢ (𝑦 = (℩𝑦 ∈ 𝐴 𝜒) → 𝐵 = 𝐶) & ⊢ ((𝜑 ∧ 𝑥 ∈ 𝐴) → ∃!𝑦 ∈ 𝐴 𝑥 = 𝐵) ⇒ ⊢ ((𝜑 ∧ ∃!𝑥 ∈ 𝐴 𝜓) → (℩𝑥 ∈ 𝐴 𝜓) = 𝐶) | ||
Theorem | eusvobj2 6963* | Specify the same property in two ways when class 𝐵(𝑦) is single-valued. (Contributed by NM, 1-Nov-2010.) (Proof shortened by Mario Carneiro, 24-Dec-2016.) |
⊢ 𝐵 ∈ V ⇒ ⊢ (∃!𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵 → (∃𝑦 ∈ 𝐴 𝑥 = 𝐵 ↔ ∀𝑦 ∈ 𝐴 𝑥 = 𝐵)) | ||
Theorem | eusvobj1 6964* | Specify the same object in two ways when class 𝐵(𝑦) is single-valued. (Contributed by NM, 1-Nov-2010.) (Proof shortened by Mario Carneiro, 19-Nov-2016.) |
⊢ 𝐵 ∈ V ⇒ ⊢ (∃!𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵 → (℩𝑥∃𝑦 ∈ 𝐴 𝑥 = 𝐵) = (℩𝑥∀𝑦 ∈ 𝐴 𝑥 = 𝐵)) | ||
Theorem | f1ofveu 6965* | There is one domain element for each value of a one-to-one onto function. (Contributed by NM, 26-May-2006.) |
⊢ ((𝐹:𝐴–1-1-onto→𝐵 ∧ 𝐶 ∈ 𝐵) → ∃!𝑥 ∈ 𝐴 (𝐹‘𝑥) = 𝐶) | ||
Theorem | f1ocnvfv3 6966* | Value of the converse of a one-to-one onto function. (Contributed by NM, 26-May-2006.) (Proof shortened by Mario Carneiro, 24-Dec-2016.) |
⊢ ((𝐹:𝐴–1-1-onto→𝐵 ∧ 𝐶 ∈ 𝐵) → (◡𝐹‘𝐶) = (℩𝑥 ∈ 𝐴 (𝐹‘𝑥) = 𝐶)) | ||
Theorem | riotaund 6967* | Restricted iota equals the empty set when not meaningful. (Contributed by NM, 16-Jan-2012.) (Revised by Mario Carneiro, 15-Oct-2016.) (Revised by NM, 13-Sep-2018.) |
⊢ (¬ ∃!𝑥 ∈ 𝐴 𝜑 → (℩𝑥 ∈ 𝐴 𝜑) = ∅) | ||
Theorem | riotassuni 6968* | The restricted iota class is limited in size by the base set. (Contributed by Mario Carneiro, 24-Dec-2016.) |
⊢ (℩𝑥 ∈ 𝐴 𝜑) ⊆ (𝒫 ∪ 𝐴 ∪ ∪ 𝐴) | ||
Theorem | riotaclb 6969* | Bidirectional closure of restricted iota when domain is not empty. (Contributed by NM, 28-Feb-2013.) (Revised by Mario Carneiro, 24-Dec-2016.) (Revised by NM, 13-Sep-2018.) |
⊢ (¬ ∅ ∈ 𝐴 → (∃!𝑥 ∈ 𝐴 𝜑 ↔ (℩𝑥 ∈ 𝐴 𝜑) ∈ 𝐴)) | ||
Syntax | co 6970 | Extend class notation to include the value of an operation 𝐹 (such as +) for two arguments 𝐴 and 𝐵. Note that the syntax is simply three class symbols in a row surrounded by parentheses. Since operation values are the only possible class expressions consisting of three class expressions in a row surrounded by parentheses, the syntax is unambiguous. (For an example of how syntax could become ambiguous if we are not careful, see the comment in cneg 10665.) |
class (𝐴𝐹𝐵) | ||
Syntax | coprab 6971 | Extend class notation to include class abstraction (class builder) of nested ordered pairs. |
class {〈〈𝑥, 𝑦〉, 𝑧〉 ∣ 𝜑} | ||
Syntax | cmpo 6972 | Extend the definition of a class to include maps-to notation for defining an operation via a rule. |
class (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐶) | ||
Definition | df-ov 6973 | Define the value of an operation. Definition of operation value in [Enderton] p. 79. Note that the syntax is simply three class expressions in a row bracketed by parentheses. There are no restrictions of any kind on what those class expressions may be, although only certain kinds of class expressions - a binary operation 𝐹 and its arguments 𝐴 and 𝐵- will be useful for proving meaningful theorems. For example, if class 𝐹 is the operation + and arguments 𝐴 and 𝐵 are 3 and 2, the expression (3 + 2) can be proved to equal 5 (see 3p2e5 11592). This definition is well-defined, although not very meaningful, when classes 𝐴 and/or 𝐵 are proper classes (i.e. are not sets); see ovprc1 7008 and ovprc2 7009. On the other hand, we often find uses for this definition when 𝐹 is a proper class, such as +o in oav 7932. 𝐹 is normally equal to a class of nested ordered pairs of the form defined by df-oprab 6974. (Contributed by NM, 28-Feb-1995.) |
⊢ (𝐴𝐹𝐵) = (𝐹‘〈𝐴, 𝐵〉) | ||
Definition | df-oprab 6974* | Define the class abstraction (class builder) of a collection of nested ordered pairs (for use in defining operations). This is a special case of Definition 4.16 of [TakeutiZaring] p. 14. Normally 𝑥, 𝑦, and 𝑧 are distinct, although the definition doesn't strictly require it. See df-ov 6973 for the value of an operation. The brace notation is called "class abstraction" by Quine; it is also called a "class builder" in the literature. The value of the most common operation class builder is given by ovmpo 7120. (Contributed by NM, 12-Mar-1995.) |
⊢ {〈〈𝑥, 𝑦〉, 𝑧〉 ∣ 𝜑} = {𝑤 ∣ ∃𝑥∃𝑦∃𝑧(𝑤 = 〈〈𝑥, 𝑦〉, 𝑧〉 ∧ 𝜑)} | ||
Definition | df-mpo 6975* | Define maps-to notation for defining an operation via a rule. Read as "the operation defined by the map from 𝑥, 𝑦 (in 𝐴 × 𝐵) to 𝐶(𝑥, 𝑦)". An extension of df-mpt 5003 for two arguments. (Contributed by NM, 17-Feb-2008.) |
⊢ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐶) = {〈〈𝑥, 𝑦〉, 𝑧〉 ∣ ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑧 = 𝐶)} | ||
Theorem | oveq 6976 | Equality theorem for operation value. (Contributed by NM, 28-Feb-1995.) |
⊢ (𝐹 = 𝐺 → (𝐴𝐹𝐵) = (𝐴𝐺𝐵)) | ||
Theorem | oveq1 6977 | Equality theorem for operation value. (Contributed by NM, 28-Feb-1995.) |
⊢ (𝐴 = 𝐵 → (𝐴𝐹𝐶) = (𝐵𝐹𝐶)) | ||
Theorem | oveq2 6978 | Equality theorem for operation value. (Contributed by NM, 28-Feb-1995.) |
⊢ (𝐴 = 𝐵 → (𝐶𝐹𝐴) = (𝐶𝐹𝐵)) | ||
Theorem | oveq12 6979 | Equality theorem for operation value. (Contributed by NM, 16-Jul-1995.) |
⊢ ((𝐴 = 𝐵 ∧ 𝐶 = 𝐷) → (𝐴𝐹𝐶) = (𝐵𝐹𝐷)) | ||
Theorem | oveq1i 6980 | Equality inference for operation value. (Contributed by NM, 28-Feb-1995.) |
⊢ 𝐴 = 𝐵 ⇒ ⊢ (𝐴𝐹𝐶) = (𝐵𝐹𝐶) | ||
Theorem | oveq2i 6981 | Equality inference for operation value. (Contributed by NM, 28-Feb-1995.) |
⊢ 𝐴 = 𝐵 ⇒ ⊢ (𝐶𝐹𝐴) = (𝐶𝐹𝐵) | ||
Theorem | oveq12i 6982 | Equality inference for operation value. (Contributed by NM, 28-Feb-1995.) (Proof shortened by Andrew Salmon, 22-Oct-2011.) |
⊢ 𝐴 = 𝐵 & ⊢ 𝐶 = 𝐷 ⇒ ⊢ (𝐴𝐹𝐶) = (𝐵𝐹𝐷) | ||
Theorem | oveqi 6983 | Equality inference for operation value. (Contributed by NM, 24-Nov-2007.) |
⊢ 𝐴 = 𝐵 ⇒ ⊢ (𝐶𝐴𝐷) = (𝐶𝐵𝐷) | ||
Theorem | oveq123i 6984 | Equality inference for operation value. (Contributed by FL, 11-Jul-2010.) |
⊢ 𝐴 = 𝐶 & ⊢ 𝐵 = 𝐷 & ⊢ 𝐹 = 𝐺 ⇒ ⊢ (𝐴𝐹𝐵) = (𝐶𝐺𝐷) | ||
Theorem | oveq1d 6985 | Equality deduction for operation value. (Contributed by NM, 13-Mar-1995.) |
⊢ (𝜑 → 𝐴 = 𝐵) ⇒ ⊢ (𝜑 → (𝐴𝐹𝐶) = (𝐵𝐹𝐶)) | ||
Theorem | oveq2d 6986 | Equality deduction for operation value. (Contributed by NM, 13-Mar-1995.) |
⊢ (𝜑 → 𝐴 = 𝐵) ⇒ ⊢ (𝜑 → (𝐶𝐹𝐴) = (𝐶𝐹𝐵)) | ||
Theorem | oveqd 6987 | Equality deduction for operation value. (Contributed by NM, 9-Sep-2006.) |
⊢ (𝜑 → 𝐴 = 𝐵) ⇒ ⊢ (𝜑 → (𝐶𝐴𝐷) = (𝐶𝐵𝐷)) | ||
Theorem | oveq12d 6988 | Equality deduction for operation value. (Contributed by NM, 13-Mar-1995.) (Proof shortened by Andrew Salmon, 22-Oct-2011.) |
⊢ (𝜑 → 𝐴 = 𝐵) & ⊢ (𝜑 → 𝐶 = 𝐷) ⇒ ⊢ (𝜑 → (𝐴𝐹𝐶) = (𝐵𝐹𝐷)) | ||
Theorem | oveqan12d 6989 | Equality deduction for operation value. (Contributed by NM, 10-Aug-1995.) |
⊢ (𝜑 → 𝐴 = 𝐵) & ⊢ (𝜓 → 𝐶 = 𝐷) ⇒ ⊢ ((𝜑 ∧ 𝜓) → (𝐴𝐹𝐶) = (𝐵𝐹𝐷)) | ||
Theorem | oveqan12rd 6990 | Equality deduction for operation value. (Contributed by NM, 10-Aug-1995.) |
⊢ (𝜑 → 𝐴 = 𝐵) & ⊢ (𝜓 → 𝐶 = 𝐷) ⇒ ⊢ ((𝜓 ∧ 𝜑) → (𝐴𝐹𝐶) = (𝐵𝐹𝐷)) | ||
Theorem | oveq123d 6991 | Equality deduction for operation value. (Contributed by FL, 22-Dec-2008.) |
⊢ (𝜑 → 𝐹 = 𝐺) & ⊢ (𝜑 → 𝐴 = 𝐵) & ⊢ (𝜑 → 𝐶 = 𝐷) ⇒ ⊢ (𝜑 → (𝐴𝐹𝐶) = (𝐵𝐺𝐷)) | ||
Theorem | fvoveq1d 6992 | Equality deduction for nested function and operation value. (Contributed by AV, 23-Jul-2022.) |
⊢ (𝜑 → 𝐴 = 𝐵) ⇒ ⊢ (𝜑 → (𝐹‘(𝐴𝑂𝐶)) = (𝐹‘(𝐵𝑂𝐶))) | ||
Theorem | fvoveq1 6993 | Equality theorem for nested function and operation value. Closed form of fvoveq1d 6992. (Contributed by AV, 23-Jul-2022.) |
⊢ (𝐴 = 𝐵 → (𝐹‘(𝐴𝑂𝐶)) = (𝐹‘(𝐵𝑂𝐶))) | ||
Theorem | ovanraleqv 6994* | Equality theorem for a conjunction with an operation values within a restricted universal quantification. Technical theorem to be used to reduce the size of a significant number of proofs. (Contributed by AV, 13-Aug-2022.) |
⊢ (𝐵 = 𝑋 → (𝜑 ↔ 𝜓)) ⇒ ⊢ (𝐵 = 𝑋 → (∀𝑥 ∈ 𝑉 (𝜑 ∧ (𝐴 · 𝐵) = 𝐶) ↔ ∀𝑥 ∈ 𝑉 (𝜓 ∧ (𝐴 · 𝑋) = 𝐶))) | ||
Theorem | imbrov2fvoveq 6995 | Equality theorem for nested function and operation value in an implication for a binary relation. Technical theorem to be used to reduce the size of a significant number of proofs. (Contributed by AV, 17-Aug-2022.) |
⊢ (𝑋 = 𝑌 → (𝜑 ↔ 𝜓)) ⇒ ⊢ (𝑋 = 𝑌 → ((𝜑 → (𝐹‘((𝐺‘𝑋) · 𝑂))𝑅𝐴) ↔ (𝜓 → (𝐹‘((𝐺‘𝑌) · 𝑂))𝑅𝐴))) | ||
Theorem | ovrspc2v 6996* | If an operation value is element of a class for all operands of two classes, then the operation value is an element of the class for specific operands of the two classes. (Contributed by Mario Carneiro, 6-Dec-2014.) |
⊢ (((𝑋 ∈ 𝐴 ∧ 𝑌 ∈ 𝐵) ∧ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐵 (𝑥𝐹𝑦) ∈ 𝐶) → (𝑋𝐹𝑌) ∈ 𝐶) | ||
Theorem | oveqrspc2v 6997* | Restricted specialization of operands, using implicit substitution. (Contributed by Mario Carneiro, 6-Dec-2014.) |
⊢ ((𝜑 ∧ (𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)) → (𝑥𝐹𝑦) = (𝑥𝐺𝑦)) ⇒ ⊢ ((𝜑 ∧ (𝑋 ∈ 𝐴 ∧ 𝑌 ∈ 𝐵)) → (𝑋𝐹𝑌) = (𝑋𝐺𝑌)) | ||
Theorem | oveqdr 6998 | Equality of two operations for any two operands. Useful in proofs using *propd theorems. (Contributed by Mario Carneiro, 29-Jun-2015.) |
⊢ (𝜑 → 𝐹 = 𝐺) ⇒ ⊢ ((𝜑 ∧ 𝜓) → (𝑥𝐹𝑦) = (𝑥𝐺𝑦)) | ||
Theorem | nfovd 6999 | Deduction version of bound-variable hypothesis builder nfov 7000. (Contributed by NM, 13-Dec-2005.) (Proof shortened by Andrew Salmon, 22-Oct-2011.) |
⊢ (𝜑 → Ⅎ𝑥𝐴) & ⊢ (𝜑 → Ⅎ𝑥𝐹) & ⊢ (𝜑 → Ⅎ𝑥𝐵) ⇒ ⊢ (𝜑 → Ⅎ𝑥(𝐴𝐹𝐵)) | ||
Theorem | nfov 7000 | Bound-variable hypothesis builder for operation value. (Contributed by NM, 4-May-2004.) |
⊢ Ⅎ𝑥𝐴 & ⊢ Ⅎ𝑥𝐹 & ⊢ Ⅎ𝑥𝐵 ⇒ ⊢ Ⅎ𝑥(𝐴𝐹𝐵) |
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