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Type | Label | Description |
---|---|---|
Statement | ||
Theorem | cbvcsbv 3901* | Change the bound variable of a proper substitution into a class using implicit substitution. (Contributed by NM, 30-Sep-2008.) (Revised by Mario Carneiro, 13-Oct-2016.) |
⊢ (𝑥 = 𝑦 → 𝐵 = 𝐶) ⇒ ⊢ ⦋𝐴 / 𝑥⦌𝐵 = ⦋𝐴 / 𝑦⦌𝐶 | ||
Theorem | csbid 3902 | Analogue of sbid 2240 for proper substitution into a class. (Contributed by NM, 10-Nov-2005.) |
⊢ ⦋𝑥 / 𝑥⦌𝐴 = 𝐴 | ||
Theorem | csbeq1a 3903 | Equality theorem for proper substitution into a class. (Contributed by NM, 10-Nov-2005.) |
⊢ (𝑥 = 𝐴 → 𝐵 = ⦋𝐴 / 𝑥⦌𝐵) | ||
Theorem | csbcow 3904* | Composition law for chained substitutions into a class. Version of csbco 3905 with a disjoint variable condition, which does not require ax-13 2366. (Contributed by NM, 10-Nov-2005.) Avoid ax-13 2366. (Revised by Gino Giotto, 10-Jan-2024.) |
⊢ ⦋𝐴 / 𝑦⦌⦋𝑦 / 𝑥⦌𝐵 = ⦋𝐴 / 𝑥⦌𝐵 | ||
Theorem | csbco 3905* | Composition law for chained substitutions into a class. Usage of this theorem is discouraged because it depends on ax-13 2366. Use the weaker csbcow 3904 when possible. (Contributed by NM, 10-Nov-2005.) (New usage is discouraged.) |
⊢ ⦋𝐴 / 𝑦⦌⦋𝑦 / 𝑥⦌𝐵 = ⦋𝐴 / 𝑥⦌𝐵 | ||
Theorem | csbtt 3906 | Substitution doesn't affect a constant 𝐵 (in which 𝑥 is not free). (Contributed by Mario Carneiro, 14-Oct-2016.) |
⊢ ((𝐴 ∈ 𝑉 ∧ Ⅎ𝑥𝐵) → ⦋𝐴 / 𝑥⦌𝐵 = 𝐵) | ||
Theorem | csbconstgf 3907 | Substitution doesn't affect a constant 𝐵 (in which 𝑥 is not free). (Contributed by NM, 10-Nov-2005.) |
⊢ Ⅎ𝑥𝐵 ⇒ ⊢ (𝐴 ∈ 𝑉 → ⦋𝐴 / 𝑥⦌𝐵 = 𝐵) | ||
Theorem | csbconstg 3908* | Substitution doesn't affect a constant 𝐵 (in which 𝑥 does not occur). csbconstgf 3907 with distinct variable requirement. (Contributed by Alan Sare, 22-Jul-2012.) Avoid ax-12 2164. (Revised by Gino Giotto, 15-Oct-2024.) |
⊢ (𝐴 ∈ 𝑉 → ⦋𝐴 / 𝑥⦌𝐵 = 𝐵) | ||
Theorem | csbconstgOLD 3909* | Obsolete version of csbconstg 3908 as of 15-Oct-2024. (Contributed by Alan Sare, 22-Jul-2012.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (𝐴 ∈ 𝑉 → ⦋𝐴 / 𝑥⦌𝐵 = 𝐵) | ||
Theorem | csbgfi 3910 | Substitution for a variable not free in a class does not affect it, in inference form. (Contributed by Giovanni Mascellani, 4-Jun-2019.) |
⊢ 𝐴 ∈ V & ⊢ Ⅎ𝑥𝐵 ⇒ ⊢ ⦋𝐴 / 𝑥⦌𝐵 = 𝐵 | ||
Theorem | csbconstgi 3911* | The proper substitution of a class for a variable in another variable does not modify it, in inference form. (Contributed by Giovanni Mascellani, 30-May-2019.) |
⊢ 𝐴 ∈ V ⇒ ⊢ ⦋𝐴 / 𝑥⦌𝑦 = 𝑦 | ||
Theorem | nfcsb1d 3912 | Bound-variable hypothesis builder for substitution into a class. (Contributed by Mario Carneiro, 12-Oct-2016.) |
⊢ (𝜑 → Ⅎ𝑥𝐴) ⇒ ⊢ (𝜑 → Ⅎ𝑥⦋𝐴 / 𝑥⦌𝐵) | ||
Theorem | nfcsb1 3913 | Bound-variable hypothesis builder for substitution into a class. (Contributed by Mario Carneiro, 12-Oct-2016.) |
⊢ Ⅎ𝑥𝐴 ⇒ ⊢ Ⅎ𝑥⦋𝐴 / 𝑥⦌𝐵 | ||
Theorem | nfcsb1v 3914* | Bound-variable hypothesis builder for substitution into a class. (Contributed by NM, 17-Aug-2006.) (Revised by Mario Carneiro, 12-Oct-2016.) |
⊢ Ⅎ𝑥⦋𝐴 / 𝑥⦌𝐵 | ||
Theorem | nfcsbd 3915 | Deduction version of nfcsb 3917. Usage of this theorem is discouraged because it depends on ax-13 2366. (Contributed by NM, 21-Nov-2005.) (Revised by Mario Carneiro, 12-Oct-2016.) (New usage is discouraged.) |
⊢ Ⅎ𝑦𝜑 & ⊢ (𝜑 → Ⅎ𝑥𝐴) & ⊢ (𝜑 → Ⅎ𝑥𝐵) ⇒ ⊢ (𝜑 → Ⅎ𝑥⦋𝐴 / 𝑦⦌𝐵) | ||
Theorem | nfcsbw 3916* | Bound-variable hypothesis builder for substitution into a class. Version of nfcsb 3917 with a disjoint variable condition, which does not require ax-13 2366. (Contributed by Mario Carneiro, 12-Oct-2016.) Avoid ax-13 2366. (Revised by Gino Giotto, 10-Jan-2024.) |
⊢ Ⅎ𝑥𝐴 & ⊢ Ⅎ𝑥𝐵 ⇒ ⊢ Ⅎ𝑥⦋𝐴 / 𝑦⦌𝐵 | ||
Theorem | nfcsb 3917 | Bound-variable hypothesis builder for substitution into a class. Usage of this theorem is discouraged because it depends on ax-13 2366. Use the weaker nfcsbw 3916 when possible. (Contributed by Mario Carneiro, 12-Oct-2016.) (New usage is discouraged.) |
⊢ Ⅎ𝑥𝐴 & ⊢ Ⅎ𝑥𝐵 ⇒ ⊢ Ⅎ𝑥⦋𝐴 / 𝑦⦌𝐵 | ||
Theorem | csbhypf 3918* | Introduce an explicit substitution into an implicit substitution hypothesis. See sbhypf 3534 for class substitution version. (Contributed by NM, 19-Dec-2008.) |
⊢ Ⅎ𝑥𝐴 & ⊢ Ⅎ𝑥𝐶 & ⊢ (𝑥 = 𝐴 → 𝐵 = 𝐶) ⇒ ⊢ (𝑦 = 𝐴 → ⦋𝑦 / 𝑥⦌𝐵 = 𝐶) | ||
Theorem | csbiebt 3919* | Conversion of implicit substitution to explicit substitution into a class. (Closed theorem version of csbiegf 3923.) (Contributed by NM, 11-Nov-2005.) |
⊢ ((𝐴 ∈ 𝑉 ∧ Ⅎ𝑥𝐶) → (∀𝑥(𝑥 = 𝐴 → 𝐵 = 𝐶) ↔ ⦋𝐴 / 𝑥⦌𝐵 = 𝐶)) | ||
Theorem | csbiedf 3920* | Conversion of implicit substitution to explicit substitution into a class. (Contributed by Mario Carneiro, 13-Oct-2016.) |
⊢ Ⅎ𝑥𝜑 & ⊢ (𝜑 → Ⅎ𝑥𝐶) & ⊢ (𝜑 → 𝐴 ∈ 𝑉) & ⊢ ((𝜑 ∧ 𝑥 = 𝐴) → 𝐵 = 𝐶) ⇒ ⊢ (𝜑 → ⦋𝐴 / 𝑥⦌𝐵 = 𝐶) | ||
Theorem | csbieb 3921* | Bidirectional conversion between an implicit class substitution hypothesis 𝑥 = 𝐴 → 𝐵 = 𝐶 and its explicit substitution equivalent. (Contributed by NM, 2-Mar-2008.) |
⊢ 𝐴 ∈ V & ⊢ Ⅎ𝑥𝐶 ⇒ ⊢ (∀𝑥(𝑥 = 𝐴 → 𝐵 = 𝐶) ↔ ⦋𝐴 / 𝑥⦌𝐵 = 𝐶) | ||
Theorem | csbiebg 3922* | Bidirectional conversion between an implicit class substitution hypothesis 𝑥 = 𝐴 → 𝐵 = 𝐶 and its explicit substitution equivalent. (Contributed by NM, 24-Mar-2013.) (Revised by Mario Carneiro, 11-Dec-2016.) |
⊢ Ⅎ𝑥𝐶 ⇒ ⊢ (𝐴 ∈ 𝑉 → (∀𝑥(𝑥 = 𝐴 → 𝐵 = 𝐶) ↔ ⦋𝐴 / 𝑥⦌𝐵 = 𝐶)) | ||
Theorem | csbiegf 3923* | Conversion of implicit substitution to explicit substitution into a class. (Contributed by NM, 11-Nov-2005.) (Revised by Mario Carneiro, 13-Oct-2016.) |
⊢ (𝐴 ∈ 𝑉 → Ⅎ𝑥𝐶) & ⊢ (𝑥 = 𝐴 → 𝐵 = 𝐶) ⇒ ⊢ (𝐴 ∈ 𝑉 → ⦋𝐴 / 𝑥⦌𝐵 = 𝐶) | ||
Theorem | csbief 3924* | Conversion of implicit substitution to explicit substitution into a class. (Contributed by NM, 26-Nov-2005.) (Revised by Mario Carneiro, 13-Oct-2016.) |
⊢ 𝐴 ∈ V & ⊢ Ⅎ𝑥𝐶 & ⊢ (𝑥 = 𝐴 → 𝐵 = 𝐶) ⇒ ⊢ ⦋𝐴 / 𝑥⦌𝐵 = 𝐶 | ||
Theorem | csbie 3925* | Conversion of implicit substitution to explicit substitution into a class. (Contributed by AV, 2-Dec-2019.) Reduce axiom usage. (Revised by Gino Giotto, 15-Oct-2024.) |
⊢ 𝐴 ∈ V & ⊢ (𝑥 = 𝐴 → 𝐵 = 𝐶) ⇒ ⊢ ⦋𝐴 / 𝑥⦌𝐵 = 𝐶 | ||
Theorem | csbieOLD 3926* | Obsolete version of csbie 3925 as of 15-Oct-2024. (Contributed by AV, 2-Dec-2019.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ 𝐴 ∈ V & ⊢ (𝑥 = 𝐴 → 𝐵 = 𝐶) ⇒ ⊢ ⦋𝐴 / 𝑥⦌𝐵 = 𝐶 | ||
Theorem | csbied 3927* | Conversion of implicit substitution to explicit substitution into a class. (Contributed by Mario Carneiro, 2-Dec-2014.) (Revised by Mario Carneiro, 13-Oct-2016.) Reduce axiom usage. (Revised by Gino Giotto, 15-Oct-2024.) |
⊢ (𝜑 → 𝐴 ∈ 𝑉) & ⊢ ((𝜑 ∧ 𝑥 = 𝐴) → 𝐵 = 𝐶) ⇒ ⊢ (𝜑 → ⦋𝐴 / 𝑥⦌𝐵 = 𝐶) | ||
Theorem | csbiedOLD 3928* | Obsolete version of csbied 3927 as of 15-Oct-2024. (Contributed by Mario Carneiro, 2-Dec-2014.) (Revised by Mario Carneiro, 13-Oct-2016.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (𝜑 → 𝐴 ∈ 𝑉) & ⊢ ((𝜑 ∧ 𝑥 = 𝐴) → 𝐵 = 𝐶) ⇒ ⊢ (𝜑 → ⦋𝐴 / 𝑥⦌𝐵 = 𝐶) | ||
Theorem | csbied2 3929* | Conversion of implicit substitution to explicit class substitution, deduction form. (Contributed by Mario Carneiro, 2-Jan-2017.) |
⊢ (𝜑 → 𝐴 ∈ 𝑉) & ⊢ (𝜑 → 𝐴 = 𝐵) & ⊢ ((𝜑 ∧ 𝑥 = 𝐵) → 𝐶 = 𝐷) ⇒ ⊢ (𝜑 → ⦋𝐴 / 𝑥⦌𝐶 = 𝐷) | ||
Theorem | csbie2t 3930* | Conversion of implicit substitution to explicit substitution into a class (closed form of csbie2 3931). (Contributed by NM, 3-Sep-2007.) (Revised by Mario Carneiro, 13-Oct-2016.) |
⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V ⇒ ⊢ (∀𝑥∀𝑦((𝑥 = 𝐴 ∧ 𝑦 = 𝐵) → 𝐶 = 𝐷) → ⦋𝐴 / 𝑥⦌⦋𝐵 / 𝑦⦌𝐶 = 𝐷) | ||
Theorem | csbie2 3931* | Conversion of implicit substitution to explicit substitution into a class. (Contributed by NM, 27-Aug-2007.) |
⊢ 𝐴 ∈ V & ⊢ 𝐵 ∈ V & ⊢ ((𝑥 = 𝐴 ∧ 𝑦 = 𝐵) → 𝐶 = 𝐷) ⇒ ⊢ ⦋𝐴 / 𝑥⦌⦋𝐵 / 𝑦⦌𝐶 = 𝐷 | ||
Theorem | csbie2g 3932* | Conversion of implicit substitution to explicit class substitution. This version of csbie 3925 avoids a disjointness condition on 𝑥, 𝐴 and 𝑥, 𝐷 by substituting twice. (Contributed by Mario Carneiro, 11-Nov-2016.) |
⊢ (𝑥 = 𝑦 → 𝐵 = 𝐶) & ⊢ (𝑦 = 𝐴 → 𝐶 = 𝐷) ⇒ ⊢ (𝐴 ∈ 𝑉 → ⦋𝐴 / 𝑥⦌𝐵 = 𝐷) | ||
Theorem | cbvrabcsfw 3933* | Version of cbvrabcsf 3937 with a disjoint variable condition, which does not require ax-13 2366. (Contributed by Andrew Salmon, 13-Jul-2011.) (Revised by Gino Giotto, 26-Jan-2024.) |
⊢ Ⅎ𝑦𝐴 & ⊢ Ⅎ𝑥𝐵 & ⊢ Ⅎ𝑦𝜑 & ⊢ Ⅎ𝑥𝜓 & ⊢ (𝑥 = 𝑦 → 𝐴 = 𝐵) & ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) ⇒ ⊢ {𝑥 ∈ 𝐴 ∣ 𝜑} = {𝑦 ∈ 𝐵 ∣ 𝜓} | ||
Theorem | cbvralcsf 3934 | A more general version of cbvralf 3351 that doesn't require 𝐴 and 𝐵 to be distinct from 𝑥 or 𝑦. Changes bound variables using implicit substitution. Usage of this theorem is discouraged because it depends on ax-13 2366. (Contributed by Andrew Salmon, 13-Jul-2011.) (New usage is discouraged.) |
⊢ Ⅎ𝑦𝐴 & ⊢ Ⅎ𝑥𝐵 & ⊢ Ⅎ𝑦𝜑 & ⊢ Ⅎ𝑥𝜓 & ⊢ (𝑥 = 𝑦 → 𝐴 = 𝐵) & ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) ⇒ ⊢ (∀𝑥 ∈ 𝐴 𝜑 ↔ ∀𝑦 ∈ 𝐵 𝜓) | ||
Theorem | cbvrexcsf 3935 | A more general version of cbvrexf 3352 that has no distinct variable restrictions. Changes bound variables using implicit substitution. Usage of this theorem is discouraged because it depends on ax-13 2366. (Contributed by Andrew Salmon, 13-Jul-2011.) (Proof shortened by Mario Carneiro, 7-Dec-2014.) (New usage is discouraged.) |
⊢ Ⅎ𝑦𝐴 & ⊢ Ⅎ𝑥𝐵 & ⊢ Ⅎ𝑦𝜑 & ⊢ Ⅎ𝑥𝜓 & ⊢ (𝑥 = 𝑦 → 𝐴 = 𝐵) & ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) ⇒ ⊢ (∃𝑥 ∈ 𝐴 𝜑 ↔ ∃𝑦 ∈ 𝐵 𝜓) | ||
Theorem | cbvreucsf 3936 | A more general version of cbvreuv 3422 that has no distinct variable restrictions. Changes bound variables using implicit substitution. Usage of this theorem is discouraged because it depends on ax-13 2366. (Contributed by Andrew Salmon, 13-Jul-2011.) (New usage is discouraged.) |
⊢ Ⅎ𝑦𝐴 & ⊢ Ⅎ𝑥𝐵 & ⊢ Ⅎ𝑦𝜑 & ⊢ Ⅎ𝑥𝜓 & ⊢ (𝑥 = 𝑦 → 𝐴 = 𝐵) & ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) ⇒ ⊢ (∃!𝑥 ∈ 𝐴 𝜑 ↔ ∃!𝑦 ∈ 𝐵 𝜓) | ||
Theorem | cbvrabcsf 3937 | A more general version of cbvrab 3468 with no distinct variable restrictions. Usage of this theorem is discouraged because it depends on ax-13 2366. (Contributed by Andrew Salmon, 13-Jul-2011.) (New usage is discouraged.) |
⊢ Ⅎ𝑦𝐴 & ⊢ Ⅎ𝑥𝐵 & ⊢ Ⅎ𝑦𝜑 & ⊢ Ⅎ𝑥𝜓 & ⊢ (𝑥 = 𝑦 → 𝐴 = 𝐵) & ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) ⇒ ⊢ {𝑥 ∈ 𝐴 ∣ 𝜑} = {𝑦 ∈ 𝐵 ∣ 𝜓} | ||
Theorem | cbvralv2 3938* | Rule used to change the bound variable in a restricted universal quantifier with implicit substitution which also changes the quantifier domain. Usage of this theorem is discouraged because it depends on ax-13 2366. (Contributed by David Moews, 1-May-2017.) (New usage is discouraged.) |
⊢ (𝑥 = 𝑦 → (𝜓 ↔ 𝜒)) & ⊢ (𝑥 = 𝑦 → 𝐴 = 𝐵) ⇒ ⊢ (∀𝑥 ∈ 𝐴 𝜓 ↔ ∀𝑦 ∈ 𝐵 𝜒) | ||
Theorem | cbvrexv2 3939* | Rule used to change the bound variable in a restricted existential quantifier with implicit substitution which also changes the quantifier domain. Usage of this theorem is discouraged because it depends on ax-13 2366. (Contributed by David Moews, 1-May-2017.) (New usage is discouraged.) |
⊢ (𝑥 = 𝑦 → (𝜓 ↔ 𝜒)) & ⊢ (𝑥 = 𝑦 → 𝐴 = 𝐵) ⇒ ⊢ (∃𝑥 ∈ 𝐴 𝜓 ↔ ∃𝑦 ∈ 𝐵 𝜒) | ||
Theorem | rspc2vd 3940* | Deduction version of 2-variable restricted specialization, using implicit substitution. Notice that the class 𝐷 for the second set variable 𝑦 may depend on the first set variable 𝑥. (Contributed by AV, 29-Mar-2021.) |
⊢ (𝑥 = 𝐴 → (𝜃 ↔ 𝜒)) & ⊢ (𝑦 = 𝐵 → (𝜒 ↔ 𝜓)) & ⊢ (𝜑 → 𝐴 ∈ 𝐶) & ⊢ ((𝜑 ∧ 𝑥 = 𝐴) → 𝐷 = 𝐸) & ⊢ (𝜑 → 𝐵 ∈ 𝐸) ⇒ ⊢ (𝜑 → (∀𝑥 ∈ 𝐶 ∀𝑦 ∈ 𝐷 𝜃 → 𝜓)) | ||
Syntax | cdif 3941 | Extend class notation to include class difference (read: "𝐴 minus 𝐵"). |
class (𝐴 ∖ 𝐵) | ||
Syntax | cun 3942 | Extend class notation to include union of two classes (read: "𝐴 union 𝐵"). |
class (𝐴 ∪ 𝐵) | ||
Syntax | cin 3943 | Extend class notation to include the intersection of two classes (read: "𝐴 intersect 𝐵"). |
class (𝐴 ∩ 𝐵) | ||
Syntax | wss 3944 | Extend wff notation to include the subclass relation. This is read "𝐴 is a subclass of 𝐵 " or "𝐵 includes 𝐴". When 𝐴 exists as a set, it is also read "𝐴 is a subset of 𝐵". |
wff 𝐴 ⊆ 𝐵 | ||
Syntax | wpss 3945 | Extend wff notation with proper subclass relation. |
wff 𝐴 ⊊ 𝐵 | ||
Theorem | difjust 3946* | Soundness justification theorem for df-dif 3947. (Contributed by Rodolfo Medina, 27-Apr-2010.) (Proof shortened by Andrew Salmon, 9-Jul-2011.) |
⊢ {𝑥 ∣ (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐵)} = {𝑦 ∣ (𝑦 ∈ 𝐴 ∧ ¬ 𝑦 ∈ 𝐵)} | ||
Definition | df-dif 3947* | Define class difference, also called relative complement. Definition 5.12 of [TakeutiZaring] p. 20. For example, ({1, 3} ∖ {1, 8}) = {3} (ex-dif 30207). Contrast this operation with union (𝐴 ∪ 𝐵) (df-un 3949) and intersection (𝐴 ∩ 𝐵) (df-in 3951). Several notations are used in the literature; we chose the ∖ convention used in Definition 5.3 of [Eisenberg] p. 67 instead of the more common minus sign to reserve the latter for later use in, e.g., arithmetic. We will use the terminology "𝐴 excludes 𝐵 " to mean 𝐴 ∖ 𝐵. We will use "𝐵 is removed from 𝐴 " to mean 𝐴 ∖ {𝐵} i.e. the removal of an element or equivalently the exclusion of a singleton. (Contributed by NM, 29-Apr-1994.) |
⊢ (𝐴 ∖ 𝐵) = {𝑥 ∣ (𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐵)} | ||
Theorem | unjust 3948* | Soundness justification theorem for df-un 3949. (Contributed by Rodolfo Medina, 28-Apr-2010.) (Proof shortened by Andrew Salmon, 9-Jul-2011.) |
⊢ {𝑥 ∣ (𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵)} = {𝑦 ∣ (𝑦 ∈ 𝐴 ∨ 𝑦 ∈ 𝐵)} | ||
Definition | df-un 3949* | Define the union of two classes. Definition 5.6 of [TakeutiZaring] p. 16. For example, ({1, 3} ∪ {1, 8}) = {1, 3, 8} (ex-un 30208). Contrast this operation with difference (𝐴 ∖ 𝐵) (df-dif 3947) and intersection (𝐴 ∩ 𝐵) (df-in 3951). For an alternate definition in terms of class difference, requiring no dummy variables, see dfun2 4255. For union defined in terms of intersection, see dfun3 4261. (Contributed by NM, 23-Aug-1993.) |
⊢ (𝐴 ∪ 𝐵) = {𝑥 ∣ (𝑥 ∈ 𝐴 ∨ 𝑥 ∈ 𝐵)} | ||
Theorem | injust 3950* | Soundness justification theorem for df-in 3951. (Contributed by Rodolfo Medina, 28-Apr-2010.) (Proof shortened by Andrew Salmon, 9-Jul-2011.) |
⊢ {𝑥 ∣ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵)} = {𝑦 ∣ (𝑦 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵)} | ||
Definition | df-in 3951* | Define the intersection of two classes. Definition 5.6 of [TakeutiZaring] p. 16. For example, ({1, 3} ∩ {1, 8}) = {1} (ex-in 30209). Contrast this operation with union (𝐴 ∪ 𝐵) (df-un 3949) and difference (𝐴 ∖ 𝐵) (df-dif 3947). For alternate definitions in terms of class difference, requiring no dummy variables, see dfin2 4256 and dfin4 4263. For intersection defined in terms of union, see dfin3 4262. (Contributed by NM, 29-Apr-1994.) |
⊢ (𝐴 ∩ 𝐵) = {𝑥 ∣ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵)} | ||
Theorem | dfin5 3952* | Alternate definition for the intersection of two classes. (Contributed by NM, 6-Jul-2005.) |
⊢ (𝐴 ∩ 𝐵) = {𝑥 ∈ 𝐴 ∣ 𝑥 ∈ 𝐵} | ||
Theorem | dfdif2 3953* | Alternate definition of class difference. (Contributed by NM, 25-Mar-2004.) |
⊢ (𝐴 ∖ 𝐵) = {𝑥 ∈ 𝐴 ∣ ¬ 𝑥 ∈ 𝐵} | ||
Theorem | eldif 3954 | Expansion of membership in a class difference. (Contributed by NM, 29-Apr-1994.) |
⊢ (𝐴 ∈ (𝐵 ∖ 𝐶) ↔ (𝐴 ∈ 𝐵 ∧ ¬ 𝐴 ∈ 𝐶)) | ||
Theorem | eldifd 3955 | If a class is in one class and not another, it is also in their difference. One-way deduction form of eldif 3954. (Contributed by David Moews, 1-May-2017.) |
⊢ (𝜑 → 𝐴 ∈ 𝐵) & ⊢ (𝜑 → ¬ 𝐴 ∈ 𝐶) ⇒ ⊢ (𝜑 → 𝐴 ∈ (𝐵 ∖ 𝐶)) | ||
Theorem | eldifad 3956 | If a class is in the difference of two classes, it is also in the minuend. One-way deduction form of eldif 3954. (Contributed by David Moews, 1-May-2017.) |
⊢ (𝜑 → 𝐴 ∈ (𝐵 ∖ 𝐶)) ⇒ ⊢ (𝜑 → 𝐴 ∈ 𝐵) | ||
Theorem | eldifbd 3957 | If a class is in the difference of two classes, it is not in the subtrahend. One-way deduction form of eldif 3954. (Contributed by David Moews, 1-May-2017.) |
⊢ (𝜑 → 𝐴 ∈ (𝐵 ∖ 𝐶)) ⇒ ⊢ (𝜑 → ¬ 𝐴 ∈ 𝐶) | ||
Theorem | elneeldif 3958 | The elements of a set difference and the minuend are not equal. (Contributed by AV, 21-Oct-2023.) |
⊢ ((𝑋 ∈ 𝐴 ∧ 𝑌 ∈ (𝐵 ∖ 𝐴)) → 𝑋 ≠ 𝑌) | ||
Theorem | velcomp 3959 | Characterization of setvar elements of the complement of a class. (Contributed by Andrew Salmon, 15-Jul-2011.) |
⊢ (𝑥 ∈ (V ∖ 𝐴) ↔ ¬ 𝑥 ∈ 𝐴) | ||
Theorem | elin 3960 | Expansion of membership in an intersection of two classes. Theorem 12 of [Suppes] p. 25. (Contributed by NM, 29-Apr-1994.) |
⊢ (𝐴 ∈ (𝐵 ∩ 𝐶) ↔ (𝐴 ∈ 𝐵 ∧ 𝐴 ∈ 𝐶)) | ||
Definition | df-ss 3961 |
Define the subclass relationship. Exercise 9 of [TakeutiZaring] p. 18.
For example, {1, 2} ⊆ {1, 2, 3} (ex-ss 30211). Note that
𝐴
⊆ 𝐴 (proved in
ssid 4000). Contrast this relationship with the
relationship 𝐴 ⊊ 𝐵 (as will be defined in df-pss 3963). For a more
traditional definition, but requiring a dummy variable, see dfss2 3964.
Other possible definitions are given by dfss3 3966, dfss4 4254, sspss 4095,
ssequn1 4176, ssequn2 4179, sseqin2 4211, and ssdif0 4359.
We prefer the label "ss" ("subset") for ⊆, despite the fact that it applies to classes. It is much more common to refer to this as the subset relation than subclass, especially since most of the time the arguments are in fact sets (and for pragmatic reasons we don't want to need to use different operations for sets). The way set.mm is set up, many things are technically classes despite morally (and provably) being sets, like 1 (cf. df-1 11132 and 1ex 11226) or ℝ ( cf. df-r 11134 and reex 11215). This has to do with the fact that there are no "set expressions": classes are expressions but there are only set variables in set.mm (cf. https://us.metamath.org/downloads/grammar-ambiguity.txt 11215). This is why we use ⊆ both for subclass relations and for subset relations and call it "subset". (Contributed by NM, 27-Apr-1994.) |
⊢ (𝐴 ⊆ 𝐵 ↔ (𝐴 ∩ 𝐵) = 𝐴) | ||
Theorem | dfss 3962 | Variant of subclass definition df-ss 3961. (Contributed by NM, 21-Jun-1993.) |
⊢ (𝐴 ⊆ 𝐵 ↔ 𝐴 = (𝐴 ∩ 𝐵)) | ||
Definition | df-pss 3963 | Define proper subclass (or strict subclass) relationship between two classes. Definition 5.9 of [TakeutiZaring] p. 17. For example, {1, 2} ⊊ {1, 2, 3} (ex-pss 30212). Note that ¬ 𝐴 ⊊ 𝐴 (proved in pssirr 4096). Contrast this relationship with the relationship 𝐴 ⊆ 𝐵 (as defined in df-ss 3961). Other possible definitions are given by dfpss2 4081 and dfpss3 4082. (Contributed by NM, 7-Feb-1996.) |
⊢ (𝐴 ⊊ 𝐵 ↔ (𝐴 ⊆ 𝐵 ∧ 𝐴 ≠ 𝐵)) | ||
Theorem | dfss2 3964* | Alternate definition of the subclass relationship between two classes. Definition 5.9 of [TakeutiZaring] p. 17. (Contributed by NM, 8-Jan-2002.) Avoid ax-10 2130, ax-11 2147, ax-12 2164. (Revised by SN, 16-May-2024.) |
⊢ (𝐴 ⊆ 𝐵 ↔ ∀𝑥(𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵)) | ||
Theorem | dfss2OLD 3965* | Obsolete version of dfss2 3964 as of 16-May-2024. (Contributed by NM, 8-Jan-2002.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (𝐴 ⊆ 𝐵 ↔ ∀𝑥(𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵)) | ||
Theorem | dfss3 3966* | Alternate definition of subclass relationship. (Contributed by NM, 14-Oct-1999.) |
⊢ (𝐴 ⊆ 𝐵 ↔ ∀𝑥 ∈ 𝐴 𝑥 ∈ 𝐵) | ||
Theorem | dfss6 3967* | Alternate definition of subclass relationship. (Contributed by RP, 16-Apr-2020.) |
⊢ (𝐴 ⊆ 𝐵 ↔ ¬ ∃𝑥(𝑥 ∈ 𝐴 ∧ ¬ 𝑥 ∈ 𝐵)) | ||
Theorem | dfss2f 3968 | Equivalence for subclass relation, using bound-variable hypotheses instead of distinct variable conditions. (Contributed by NM, 3-Jul-1994.) (Revised by Andrew Salmon, 27-Aug-2011.) Avoid ax-13 2366. (Revised by Gino Giotto, 19-May-2023.) |
⊢ Ⅎ𝑥𝐴 & ⊢ Ⅎ𝑥𝐵 ⇒ ⊢ (𝐴 ⊆ 𝐵 ↔ ∀𝑥(𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵)) | ||
Theorem | dfss3f 3969 | Equivalence for subclass relation, using bound-variable hypotheses instead of distinct variable conditions. (Contributed by NM, 20-Mar-2004.) |
⊢ Ⅎ𝑥𝐴 & ⊢ Ⅎ𝑥𝐵 ⇒ ⊢ (𝐴 ⊆ 𝐵 ↔ ∀𝑥 ∈ 𝐴 𝑥 ∈ 𝐵) | ||
Theorem | nfss 3970 | If 𝑥 is not free in 𝐴 and 𝐵, it is not free in 𝐴 ⊆ 𝐵. (Contributed by NM, 27-Dec-1996.) |
⊢ Ⅎ𝑥𝐴 & ⊢ Ⅎ𝑥𝐵 ⇒ ⊢ Ⅎ𝑥 𝐴 ⊆ 𝐵 | ||
Theorem | ssel 3971 | Membership relationships follow from a subclass relationship. (Contributed by NM, 5-Aug-1993.) Avoid ax-12 2164. (Revised by SN, 27-May-2024.) |
⊢ (𝐴 ⊆ 𝐵 → (𝐶 ∈ 𝐴 → 𝐶 ∈ 𝐵)) | ||
Theorem | sselOLD 3972 | Obsolete version of ssel 3971 as of 27-May-2024. (Contributed by NM, 5-Aug-1993.) (Proof modification is discouraged.) (New usage is discouraged.) |
⊢ (𝐴 ⊆ 𝐵 → (𝐶 ∈ 𝐴 → 𝐶 ∈ 𝐵)) | ||
Theorem | ssel2 3973 | Membership relationships follow from a subclass relationship. (Contributed by NM, 7-Jun-2004.) |
⊢ ((𝐴 ⊆ 𝐵 ∧ 𝐶 ∈ 𝐴) → 𝐶 ∈ 𝐵) | ||
Theorem | sseli 3974 | Membership implication from subclass relationship. (Contributed by NM, 5-Aug-1993.) |
⊢ 𝐴 ⊆ 𝐵 ⇒ ⊢ (𝐶 ∈ 𝐴 → 𝐶 ∈ 𝐵) | ||
Theorem | sselii 3975 | Membership inference from subclass relationship. (Contributed by NM, 31-May-1999.) |
⊢ 𝐴 ⊆ 𝐵 & ⊢ 𝐶 ∈ 𝐴 ⇒ ⊢ 𝐶 ∈ 𝐵 | ||
Theorem | sselid 3976 | Membership inference from subclass relationship. (Contributed by NM, 25-Jun-2014.) |
⊢ 𝐴 ⊆ 𝐵 & ⊢ (𝜑 → 𝐶 ∈ 𝐴) ⇒ ⊢ (𝜑 → 𝐶 ∈ 𝐵) | ||
Theorem | sseld 3977 | Membership deduction from subclass relationship. (Contributed by NM, 15-Nov-1995.) |
⊢ (𝜑 → 𝐴 ⊆ 𝐵) ⇒ ⊢ (𝜑 → (𝐶 ∈ 𝐴 → 𝐶 ∈ 𝐵)) | ||
Theorem | sselda 3978 | Membership deduction from subclass relationship. (Contributed by NM, 26-Jun-2014.) |
⊢ (𝜑 → 𝐴 ⊆ 𝐵) ⇒ ⊢ ((𝜑 ∧ 𝐶 ∈ 𝐴) → 𝐶 ∈ 𝐵) | ||
Theorem | sseldd 3979 | Membership inference from subclass relationship. (Contributed by NM, 14-Dec-2004.) |
⊢ (𝜑 → 𝐴 ⊆ 𝐵) & ⊢ (𝜑 → 𝐶 ∈ 𝐴) ⇒ ⊢ (𝜑 → 𝐶 ∈ 𝐵) | ||
Theorem | ssneld 3980 | If a class is not in another class, it is also not in a subclass of that class. Deduction form. (Contributed by David Moews, 1-May-2017.) |
⊢ (𝜑 → 𝐴 ⊆ 𝐵) ⇒ ⊢ (𝜑 → (¬ 𝐶 ∈ 𝐵 → ¬ 𝐶 ∈ 𝐴)) | ||
Theorem | ssneldd 3981 | If an element is not in a class, it is also not in a subclass of that class. Deduction form. (Contributed by David Moews, 1-May-2017.) |
⊢ (𝜑 → 𝐴 ⊆ 𝐵) & ⊢ (𝜑 → ¬ 𝐶 ∈ 𝐵) ⇒ ⊢ (𝜑 → ¬ 𝐶 ∈ 𝐴) | ||
Theorem | ssriv 3982* | Inference based on subclass definition. (Contributed by NM, 21-Jun-1993.) |
⊢ (𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵) ⇒ ⊢ 𝐴 ⊆ 𝐵 | ||
Theorem | ssrd 3983 | Deduction based on subclass definition. (Contributed by Thierry Arnoux, 8-Mar-2017.) |
⊢ Ⅎ𝑥𝜑 & ⊢ Ⅎ𝑥𝐴 & ⊢ Ⅎ𝑥𝐵 & ⊢ (𝜑 → (𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵)) ⇒ ⊢ (𝜑 → 𝐴 ⊆ 𝐵) | ||
Theorem | ssrdv 3984* | Deduction based on subclass definition. (Contributed by NM, 15-Nov-1995.) |
⊢ (𝜑 → (𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵)) ⇒ ⊢ (𝜑 → 𝐴 ⊆ 𝐵) | ||
Theorem | sstr2 3985 | Transitivity of subclass relationship. Exercise 5 of [TakeutiZaring] p. 17. (Contributed by NM, 24-Jun-1993.) (Proof shortened by Andrew Salmon, 14-Jun-2011.) |
⊢ (𝐴 ⊆ 𝐵 → (𝐵 ⊆ 𝐶 → 𝐴 ⊆ 𝐶)) | ||
Theorem | sstr 3986 | Transitivity of subclass relationship. Theorem 6 of [Suppes] p. 23. (Contributed by NM, 5-Sep-2003.) |
⊢ ((𝐴 ⊆ 𝐵 ∧ 𝐵 ⊆ 𝐶) → 𝐴 ⊆ 𝐶) | ||
Theorem | sstri 3987 | Subclass transitivity inference. (Contributed by NM, 5-May-2000.) |
⊢ 𝐴 ⊆ 𝐵 & ⊢ 𝐵 ⊆ 𝐶 ⇒ ⊢ 𝐴 ⊆ 𝐶 | ||
Theorem | sstrd 3988 | Subclass transitivity deduction. (Contributed by NM, 2-Jun-2004.) |
⊢ (𝜑 → 𝐴 ⊆ 𝐵) & ⊢ (𝜑 → 𝐵 ⊆ 𝐶) ⇒ ⊢ (𝜑 → 𝐴 ⊆ 𝐶) | ||
Theorem | sstrid 3989 | Subclass transitivity deduction. (Contributed by NM, 6-Feb-2014.) |
⊢ 𝐴 ⊆ 𝐵 & ⊢ (𝜑 → 𝐵 ⊆ 𝐶) ⇒ ⊢ (𝜑 → 𝐴 ⊆ 𝐶) | ||
Theorem | sstrdi 3990 | Subclass transitivity deduction. (Contributed by Jonathan Ben-Naim, 3-Jun-2011.) |
⊢ (𝜑 → 𝐴 ⊆ 𝐵) & ⊢ 𝐵 ⊆ 𝐶 ⇒ ⊢ (𝜑 → 𝐴 ⊆ 𝐶) | ||
Theorem | sylan9ss 3991 | A subclass transitivity deduction. (Contributed by NM, 27-Sep-2004.) (Proof shortened by Andrew Salmon, 14-Jun-2011.) |
⊢ (𝜑 → 𝐴 ⊆ 𝐵) & ⊢ (𝜓 → 𝐵 ⊆ 𝐶) ⇒ ⊢ ((𝜑 ∧ 𝜓) → 𝐴 ⊆ 𝐶) | ||
Theorem | sylan9ssr 3992 | A subclass transitivity deduction. (Contributed by NM, 27-Sep-2004.) |
⊢ (𝜑 → 𝐴 ⊆ 𝐵) & ⊢ (𝜓 → 𝐵 ⊆ 𝐶) ⇒ ⊢ ((𝜓 ∧ 𝜑) → 𝐴 ⊆ 𝐶) | ||
Theorem | eqss 3993 | The subclass relationship is antisymmetric. Compare Theorem 4 of [Suppes] p. 22. (Contributed by NM, 21-May-1993.) |
⊢ (𝐴 = 𝐵 ↔ (𝐴 ⊆ 𝐵 ∧ 𝐵 ⊆ 𝐴)) | ||
Theorem | eqssi 3994 | Infer equality from two subclass relationships. Compare Theorem 4 of [Suppes] p. 22. (Contributed by NM, 9-Sep-1993.) |
⊢ 𝐴 ⊆ 𝐵 & ⊢ 𝐵 ⊆ 𝐴 ⇒ ⊢ 𝐴 = 𝐵 | ||
Theorem | eqssd 3995 | Equality deduction from two subclass relationships. Compare Theorem 4 of [Suppes] p. 22. (Contributed by NM, 27-Jun-2004.) |
⊢ (𝜑 → 𝐴 ⊆ 𝐵) & ⊢ (𝜑 → 𝐵 ⊆ 𝐴) ⇒ ⊢ (𝜑 → 𝐴 = 𝐵) | ||
Theorem | sssseq 3996 | If a class is a subclass of another class, then the classes are equal if and only if the other class is a subclass of the first class. (Contributed by AV, 23-Dec-2020.) |
⊢ (𝐵 ⊆ 𝐴 → (𝐴 ⊆ 𝐵 ↔ 𝐴 = 𝐵)) | ||
Theorem | eqrd 3997 | Deduce equality of classes from equivalence of membership. (Contributed by Thierry Arnoux, 21-Mar-2017.) (Proof shortened by BJ, 1-Dec-2021.) |
⊢ Ⅎ𝑥𝜑 & ⊢ Ⅎ𝑥𝐴 & ⊢ Ⅎ𝑥𝐵 & ⊢ (𝜑 → (𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵)) ⇒ ⊢ (𝜑 → 𝐴 = 𝐵) | ||
Theorem | eqri 3998 | Infer equality of classes from equivalence of membership. (Contributed by Thierry Arnoux, 7-Oct-2017.) |
⊢ Ⅎ𝑥𝐴 & ⊢ Ⅎ𝑥𝐵 & ⊢ (𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵) ⇒ ⊢ 𝐴 = 𝐵 | ||
Theorem | eqelssd 3999* | Equality deduction from subclass relationship and membership. (Contributed by AV, 21-Aug-2022.) |
⊢ (𝜑 → 𝐴 ⊆ 𝐵) & ⊢ ((𝜑 ∧ 𝑥 ∈ 𝐵) → 𝑥 ∈ 𝐴) ⇒ ⊢ (𝜑 → 𝐴 = 𝐵) | ||
Theorem | ssid 4000 | Any class is a subclass of itself. Exercise 10 of [TakeutiZaring] p. 18. (Contributed by NM, 21-Jun-1993.) (Proof shortened by Andrew Salmon, 14-Jun-2011.) |
⊢ 𝐴 ⊆ 𝐴 |
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