mathlib documentation

data.set.basic

Basic properties of sets #

THIS FILE IS SYNCHRONIZED WITH MATHLIB4. Any changes to this file require a corresponding PR to mathlib4.

Sets in Lean are homogeneous; all their elements have the same type. Sets whose elements have type X are thus defined as set X := X → Prop. Note that this function need not be decidable. The definition is in the core library.

This file provides some basic definitions related to sets and functions not present in the core library, as well as extra lemmas for functions in the core library (empty set, univ, union, intersection, insert, singleton, set-theoretic difference, complement, and powerset).

Note that a set is a term, not a type. There is a coercion from set α to Type* sending s to the corresponding subtype ↥s.

See also the file set_theory/zfc.lean, which contains an encoding of ZFC set theory in Lean.

Main definitions #

Notation used here:

Definitions in the file:

Notation #

Implementation notes #

Tags #

set, sets, subset, subsets, union, intersection, insert, singleton, complement, powerset

Set coercion to a type #

@[protected, instance]
def set.has_le {α : Type u_1} :
has_le (set α)
Equations
@[protected, instance]
def set.has_subset {α : Type u_1} :
Equations
@[protected, instance]
def set.boolean_algebra {α : Type u_1} :
Equations
@[protected, instance]
def set.has_ssubset {α : Type u_1} :
Equations
@[protected, instance]
def set.has_union {α : Type u_1} :
Equations
@[protected, instance]
def set.has_inter {α : Type u_1} :
Equations
@[simp]
theorem set.top_eq_univ {α : Type u_1} :
@[simp]
theorem set.bot_eq_empty {α : Type u_1} :
@[simp]
@[simp]
@[simp]
theorem set.le_iff_subset {α : Type u_1} {s t : set α} :
s t s t
theorem set.lt_iff_ssubset {α : Type u_1} {s t : set α} :
s < t s t
theorem has_le.le.subset {α : Type u_1} {s t : set α} :
s t s t

Alias of the forward direction of set.le_iff_subset.

theorem has_subset.subset.le {α : Type u_1} {s t : set α} :
s t s t

Alias of the reverse direction of set.le_iff_subset.

theorem has_ssubset.ssubset.lt {α : Type u_1} {s t : set α} :
s t s < t

Alias of the reverse direction of set.lt_iff_ssubset.

theorem has_lt.lt.ssubset {α : Type u_1} {s t : set α} :
s < t s t

Alias of the forward direction of set.lt_iff_ssubset.

@[protected, instance]
def set.has_coe_to_sort {α : Type u} :

Coercion from a set to the corresponding subtype.

Equations
@[protected, instance]
def set.pi_set_coe.can_lift (ι : Type u) (α : ι Type v) [ne : (i : ι), nonempty (α i)] (s : set ι) :
can_lift (Π (i : s), α i) (Π (i : ι), α i) (λ (f : Π (i : ι), α i) (i : s), f i) (λ (_x : Π (i : s), α i), true)
Equations
@[protected, instance]
def set.pi_set_coe.can_lift' (ι : Type u) (α : Type v) [ne : nonempty α] (s : set ι) :
can_lift (s α) α) (λ (f : ι α) (i : s), f i) (λ (_x : s α), true)
Equations
theorem set.coe_eq_subtype {α : Type u} (s : set α) :
s = {x // x s}
@[simp]
theorem set.coe_set_of {α : Type u} (p : α Prop) :
{x : α | p x} = {x // p x}
@[simp]
theorem set_coe.forall {α : Type u} {s : set α} {p : s Prop} :
( (x : s), p x) (x : α) (h : x s), p x, h⟩
@[simp]
theorem set_coe.exists {α : Type u} {s : set α} {p : s Prop} :
( (x : s), p x) (x : α) (h : x s), p x, h⟩
theorem set_coe.exists' {α : Type u} {s : set α} {p : Π (x : α), x s Prop} :
( (x : α) (h : x s), p x h) (x : s), p x _
theorem set_coe.forall' {α : Type u} {s : set α} {p : Π (x : α), x s Prop} :
( (x : α) (h : x s), p x h) (x : s), p x _
@[simp]
theorem set_coe_cast {α : Type u} {s t : set α} (H' : s = t) (H : s = t) (x : s) :
cast H x = x.val, _⟩
theorem set_coe.ext {α : Type u} {s : set α} {a b : s} :
a = b a = b
theorem set_coe.ext_iff {α : Type u} {s : set α} {a b : s} :
a = b a = b
theorem subtype.mem {α : Type u_1} {s : set α} (p : s) :
p s

See also subtype.prop

theorem eq.subset {α : Type u_1} {s t : set α} :
s = t s t

Duplicate of eq.subset', which currently has elaboration problems.

@[protected, instance]
def set.inhabited {α : Type u} :
Equations
@[ext]
theorem set.ext {α : Type u} {a b : set α} (h : (x : α), x a x b) :
a = b
theorem set.ext_iff {α : Type u} {s t : set α} :
s = t (x : α), x s x t
@[trans]
theorem set.mem_of_mem_of_subset {α : Type u} {x : α} {s t : set α} (hx : x s) (h : s t) :
x t
theorem set.forall_in_swap {α : Type u} {β : Type v} {s : set α} {p : α β Prop} :
( (a : α), a s (b : β), p a b) (b : β) (a : α), a s p a b

Lemmas about mem and set_of #

theorem set.mem_set_of {α : Type u} {a : α} {p : α Prop} :
a {x : α | p x} p a
theorem has_mem.mem.out {α : Type u} {p : α Prop} {a : α} (h : a {x : α | p x}) :
p a

If h : a ∈ {x | p x} then h.out : p x. These are definitionally equal, but this can nevertheless be useful for various reasons, e.g. to apply further projection notation or in an argument to simp.

theorem set.nmem_set_of_iff {α : Type u} {a : α} {p : α Prop} :
a {x : α | p x} ¬p a
@[simp]
theorem set.set_of_mem_eq {α : Type u} {s : set α} :
{x : α | x s} = s
theorem set.set_of_set {α : Type u} {s : set α} :
set_of s = s
theorem set.set_of_app_iff {α : Type u} {p : α Prop} {x : α} :
{x : α | p x} x p x
theorem set.mem_def {α : Type u} {a : α} {s : set α} :
a s s a
@[simp]
theorem set.set_of_subset_set_of {α : Type u} {p q : α Prop} :
{a : α | p a} {a : α | q a} (a : α), p a q a
theorem set.set_of_and {α : Type u} {p q : α Prop} :
{a : α | p a q a} = {a : α | p a} {a : α | q a}
theorem set.set_of_or {α : Type u} {p q : α Prop} :
{a : α | p a q a} = {a : α | p a} {a : α | q a}

Subset and strict subset relations #

@[protected, instance]
@[protected, instance]
@[protected, instance]
@[protected, instance]
@[protected, instance]
@[protected, instance]
theorem set.subset_def {α : Type u} {s t : set α} :
s t = (x : α), x s x t
theorem set.ssubset_def {α : Type u} {s t : set α} :
s t = (s t ¬t s)
@[refl]
theorem set.subset.refl {α : Type u} (a : set α) :
a a
theorem set.subset.rfl {α : Type u} {s : set α} :
s s
@[trans]
theorem set.subset.trans {α : Type u} {a b c : set α} (ab : a b) (bc : b c) :
a c
@[trans]
theorem set.mem_of_eq_of_mem {α : Type u} {x y : α} {s : set α} (hx : x = y) (h : y s) :
x s
theorem set.subset.antisymm {α : Type u} {a b : set α} (h₁ : a b) (h₂ : b a) :
a = b
theorem set.subset.antisymm_iff {α : Type u} {a b : set α} :
a = b a b b a
theorem set.eq_of_subset_of_subset {α : Type u} {a b : set α} :
a b b a a = b
theorem set.mem_of_subset_of_mem {α : Type u} {s₁ s₂ : set α} {a : α} (h : s₁ s₂) :
a s₁ a s₂
theorem set.not_mem_subset {α : Type u} {a : α} {s t : set α} (h : s t) :
a t a s
theorem set.not_subset {α : Type u} {s t : set α} :
¬s t (a : α) (H : a s), a t

Definition of strict subsets s ⊂ t and basic properties. #

@[protected]
theorem set.eq_or_ssubset_of_subset {α : Type u} {s t : set α} (h : s t) :
s = t s t
theorem set.exists_of_ssubset {α : Type u} {s t : set α} (h : s t) :
(x : α) (H : x t), x s
@[protected]
theorem set.ssubset_iff_subset_ne {α : Type u} {s t : set α} :
s t s t s t
theorem set.ssubset_iff_of_subset {α : Type u} {s t : set α} (h : s t) :
s t (x : α) (H : x t), x s
@[protected]
theorem set.ssubset_of_ssubset_of_subset {α : Type u} {s₁ s₂ s₃ : set α} (hs₁s₂ : s₁ s₂) (hs₂s₃ : s₂ s₃) :
s₁ s₃
@[protected]
theorem set.ssubset_of_subset_of_ssubset {α : Type u} {s₁ s₂ s₃ : set α} (hs₁s₂ : s₁ s₂) (hs₂s₃ : s₂ s₃) :
s₁ s₃
theorem set.not_mem_empty {α : Type u} (x : α) :
@[simp]
theorem set.not_not_mem {α : Type u} {a : α} {s : set α} :
¬a s a s

Non-empty sets #

@[protected]
def set.nonempty {α : Type u} (s : set α) :
Prop

The property s.nonempty expresses the fact that the set s is not empty. It should be used in theorem assumptions instead of ∃ x, x ∈ s or s ≠ ∅ as it gives access to a nice API thanks to the dot notation.

Equations
@[simp]
theorem set.nonempty_coe_sort {α : Type u} {s : set α} :
theorem set.nonempty.coe_sort {α : Type u} {s : set α} :

Alias of the reverse direction of set.nonempty_coe_sort.

theorem set.nonempty_def {α : Type u} {s : set α} :
s.nonempty (x : α), x s
theorem set.nonempty_of_mem {α : Type u} {s : set α} {x : α} (h : x s) :
theorem set.nonempty.not_subset_empty {α : Type u} {s : set α} :
@[protected]
noncomputable def set.nonempty.some {α : Type u} {s : set α} (h : s.nonempty) :
α

Extract a witness from s.nonempty. This function might be used instead of case analysis on the argument. Note that it makes a proof depend on the classical.choice axiom.

Equations
@[protected]
theorem set.nonempty.some_mem {α : Type u} {s : set α} (h : s.nonempty) :
h.some s
theorem set.nonempty.mono {α : Type u} {s t : set α} (ht : s t) (hs : s.nonempty) :
theorem set.nonempty_of_not_subset {α : Type u} {s t : set α} (h : ¬s t) :
(s \ t).nonempty
theorem set.nonempty_of_ssubset {α : Type u} {s t : set α} (ht : s t) :
(t \ s).nonempty
theorem set.nonempty.of_diff {α : Type u} {s t : set α} (h : (s \ t).nonempty) :
theorem set.nonempty_of_ssubset' {α : Type u} {s t : set α} (ht : s t) :
theorem set.nonempty.inl {α : Type u} {s t : set α} (hs : s.nonempty) :
theorem set.nonempty.inr {α : Type u} {s t : set α} (ht : t.nonempty) :
@[simp]
theorem set.union_nonempty {α : Type u} {s t : set α} :
theorem set.nonempty.left {α : Type u} {s t : set α} (h : (s t).nonempty) :
theorem set.nonempty.right {α : Type u} {s t : set α} (h : (s t).nonempty) :
theorem set.inter_nonempty {α : Type u} {s t : set α} :
(s t).nonempty (x : α), x s x t
theorem set.inter_nonempty_iff_exists_left {α : Type u} {s t : set α} :
(s t).nonempty (x : α) (H : x s), x t
theorem set.inter_nonempty_iff_exists_right {α : Type u} {s t : set α} :
(s t).nonempty (x : α) (H : x t), x s
@[simp]
theorem set.univ_nonempty {α : Type u} [h : nonempty α] :
theorem set.nonempty.to_subtype {α : Type u} {s : set α} :
theorem set.nonempty.to_type {α : Type u} {s : set α} :
@[protected, instance]

Lemmas about the empty set #

theorem set.empty_def {α : Type u} :
= {x : α | false}
@[simp]
theorem set.mem_empty_iff_false {α : Type u} (x : α) :
@[simp]
theorem set.set_of_false {α : Type u} :
{a : α | false} =
@[simp]
theorem set.empty_subset {α : Type u} (s : set α) :
theorem set.subset_empty_iff {α : Type u} {s : set α} :
theorem set.eq_empty_iff_forall_not_mem {α : Type u} {s : set α} :
s = (x : α), x s
theorem set.eq_empty_of_forall_not_mem {α : Type u} {s : set α} (h : (x : α), x s) :
s =
theorem set.eq_empty_of_subset_empty {α : Type u} {s : set α} :
theorem set.eq_empty_of_is_empty {α : Type u} [is_empty α] (s : set α) :
s =
@[protected, instance]
def set.unique_empty {α : Type u} [is_empty α] :
unique (set α)

There is exactly one set of a type that is empty.

Equations
theorem set.nonempty.ne_empty {α : Type u} {s : set α} :

Alias of the forward direction of set.nonempty_iff_ne_empty.

@[simp]
@[simp]
theorem set.is_empty_coe_sort {α : Type u} {s : set α} :
theorem set.eq_empty_or_nonempty {α : Type u} (s : set α) :
theorem set.subset_eq_empty {α : Type u} {s t : set α} (h : t s) (e : s = ) :
t =
theorem set.ball_empty_iff {α : Type u} {p : α Prop} :
( (x : α), x p x) true
@[protected, instance]
@[simp]
theorem set.empty_ssubset {α : Type u} {s : set α} :
theorem set.nonempty.empty_ssubset {α : Type u} {s : set α} :

Alias of the reverse direction of set.empty_ssubset.

Universal set. #

In Lean @univ α (or univ : set α) is the set that contains all elements of type α. Mathematically it is the same as α but it has a different type.

@[simp]
theorem set.set_of_true {α : Type u} :
{x : α | true} = set.univ
@[simp]
theorem set.mem_univ {α : Type u} (x : α) :
@[simp]
theorem set.empty_ne_univ {α : Type u} [nonempty α] :
@[simp]
theorem set.subset_univ {α : Type u} (s : set α) :
theorem set.univ_subset_iff {α : Type u} {s : set α} :
theorem set.eq_univ_of_univ_subset {α : Type u} {s : set α} :

Alias of the forward direction of set.univ_subset_iff.

theorem set.eq_univ_iff_forall {α : Type u} {s : set α} :
s = set.univ (x : α), x s
theorem set.eq_univ_of_forall {α : Type u} {s : set α} :
( (x : α), x s) s = set.univ
theorem set.nonempty.eq_univ {α : Type u} {s : set α} [subsingleton α] :
theorem set.eq_univ_of_subset {α : Type u} {s t : set α} (h : s t) (hs : s = set.univ) :
theorem set.exists_mem_of_nonempty (α : Type u_1) [nonempty α] :
(x : α), x set.univ
theorem set.ne_univ_iff_exists_not_mem {α : Type u_1} (s : set α) :
s set.univ (a : α), a s
theorem set.not_subset_iff_exists_mem_not_mem {α : Type u_1} {s t : set α} :
¬s t (x : α), x s x t
theorem set.ssubset_univ_iff {α : Type u} {s : set α} :
@[protected, instance]

Lemmas about union #

theorem set.union_def {α : Type u} {s₁ s₂ : set α} :
s₁ s₂ = {a : α | a s₁ a s₂}
theorem set.mem_union_left {α : Type u} {x : α} {a : set α} (b : set α) :
x a x a b
theorem set.mem_union_right {α : Type u} {x : α} {b : set α} (a : set α) :
x b x a b
theorem set.mem_or_mem_of_mem_union {α : Type u} {x : α} {a b : set α} (H : x a b) :
x a x b
theorem set.mem_union.elim {α : Type u} {x : α} {a b : set α} {P : Prop} (H₁ : x a b) (H₂ : x a P) (H₃ : x b P) :
P
@[simp]
theorem set.mem_union {α : Type u} (x : α) (a b : set α) :
x a b x a x b
@[simp]
theorem set.union_self {α : Type u} (a : set α) :
a a = a
@[simp]
theorem set.union_empty {α : Type u} (a : set α) :
a = a
@[simp]
theorem set.empty_union {α : Type u} (a : set α) :
a = a
theorem set.union_comm {α : Type u} (a b : set α) :
a b = b a
theorem set.union_assoc {α : Type u} (a b c : set α) :
a b c = a (b c)
@[protected, instance]
@[protected, instance]
theorem set.union_left_comm {α : Type u} (s₁ s₂ s₃ : set α) :
s₁ (s₂ s₃) = s₂ (s₁ s₃)
theorem set.union_right_comm {α : Type u} (s₁ s₂ s₃ : set α) :
s₁ s₂ s₃ = s₁ s₃ s₂
@[simp]
theorem set.union_eq_left_iff_subset {α : Type u} {s t : set α} :
s t = s t s
@[simp]
theorem set.union_eq_right_iff_subset {α : Type u} {s t : set α} :
s t = t s t
theorem set.union_eq_self_of_subset_left {α : Type u} {s t : set α} (h : s t) :
s t = t
theorem set.union_eq_self_of_subset_right {α : Type u} {s t : set α} (h : t s) :
s t = s
@[simp]
theorem set.subset_union_left {α : Type u} (s t : set α) :
s s t
@[simp]
theorem set.subset_union_right {α : Type u} (s t : set α) :
t s t
theorem set.union_subset {α : Type u} {s t r : set α} (sr : s r) (tr : t r) :
s t r
@[simp]
theorem set.union_subset_iff {α : Type u} {s t u : set α} :
s t u s u t u
theorem set.union_subset_union {α : Type u} {s₁ s₂ t₁ t₂ : set α} (h₁ : s₁ s₂) (h₂ : t₁ t₂) :
s₁ t₁ s₂ t₂
theorem set.union_subset_union_left {α : Type u} {s₁ s₂ : set α} (t : set α) (h : s₁ s₂) :
s₁ t s₂ t
theorem set.union_subset_union_right {α : Type u} (s : set α) {t₁ t₂ : set α} (h : t₁ t₂) :
s t₁ s t₂
theorem set.subset_union_of_subset_left {α : Type u} {s t : set α} (h : s t) (u : set α) :
s t u
theorem set.subset_union_of_subset_right {α : Type u} {s u : set α} (h : s u) (t : set α) :
s t u
theorem set.union_congr_left {α : Type u} {s t u : set α} (ht : t s u) (hu : u s t) :
s t = s u
theorem set.union_congr_right {α : Type u} {s t u : set α} (hs : s t u) (ht : t s u) :
s u = t u
theorem set.union_eq_union_iff_left {α : Type u} {s t u : set α} :
s t = s u t s u u s t
theorem set.union_eq_union_iff_right {α : Type u} {s t u : set α} :
s u = t u s t u t s u
@[simp]
theorem set.union_empty_iff {α : Type u} {s t : set α} :
s t = s = t =
@[simp]
theorem set.union_univ {α : Type u} {s : set α} :
@[simp]
theorem set.univ_union {α : Type u} {s : set α} :

Lemmas about intersection #

theorem set.inter_def {α : Type u} {s₁ s₂ : set α} :
s₁ s₂ = {a : α | a s₁ a s₂}
@[simp]
theorem set.mem_inter_iff {α : Type u} (x : α) (a b : set α) :
x a b x a x b
theorem set.mem_inter {α : Type u} {x : α} {a b : set α} (ha : x a) (hb : x b) :
x a b
theorem set.mem_of_mem_inter_left {α : Type u} {x : α} {a b : set α} (h : x a b) :
x a
theorem set.mem_of_mem_inter_right {α : Type u} {x : α} {a b : set α} (h : x a b) :
x b
@[simp]
theorem set.inter_self {α : Type u} (a : set α) :
a a = a
@[simp]
theorem set.inter_empty {α : Type u} (a : set α) :
@[simp]
theorem set.empty_inter {α : Type u} (a : set α) :
theorem set.inter_comm {α : Type u} (a b : set α) :
a b = b a
theorem set.inter_assoc {α : Type u} (a b c : set α) :
a b c = a (b c)
@[protected, instance]
@[protected, instance]
theorem set.inter_left_comm {α : Type u} (s₁ s₂ s₃ : set α) :
s₁ (s₂ s₃) = s₂ (s₁ s₃)
theorem set.inter_right_comm {α : Type u} (s₁ s₂ s₃ : set α) :
s₁ s₂ s₃ = s₁ s₃ s₂
@[simp]
theorem set.inter_subset_left {α : Type u} (s t : set α) :
s t s
@[simp]
theorem set.inter_subset_right {α : Type u} (s t : set α) :
s t t
theorem set.subset_inter {α : Type u} {s t r : set α} (rs : r s) (rt : r t) :
r s t
@[simp]
theorem set.subset_inter_iff {α : Type u} {s t r : set α} :
r s t r s r t
@[simp]
theorem set.inter_eq_left_iff_subset {α : Type u} {s t : set α} :
s t = s s t
@[simp]
theorem set.inter_eq_right_iff_subset {α : Type u} {s t : set α} :
s t = t t s
theorem set.inter_eq_self_of_subset_left {α : Type u} {s t : set α} :
s t s t = s
theorem set.inter_eq_self_of_subset_right {α : Type u} {s t : set α} :
t s s t = t
theorem set.inter_congr_left {α : Type u} {s t u : set α} (ht : s u t) (hu : s t u) :
s t = s u
theorem set.inter_congr_right {α : Type u} {s t u : set α} (hs : t u s) (ht : s u t) :
s u = t u
theorem set.inter_eq_inter_iff_left {α : Type u} {s t u : set α} :
s t = s u s u t s t u
theorem set.inter_eq_inter_iff_right {α : Type u} {s t u : set α} :
s u = t u t u s s u t
@[simp]
theorem set.inter_univ {α : Type u} (a : set α) :
@[simp]
theorem set.univ_inter {α : Type u} (a : set α) :
theorem set.inter_subset_inter {α : Type u} {s₁ s₂ t₁ t₂ : set α} (h₁ : s₁ t₁) (h₂ : s₂ t₂) :
s₁ s₂ t₁ t₂
theorem set.inter_subset_inter_left {α : Type u} {s t : set α} (u : set α) (H : s t) :
s u t u
theorem set.inter_subset_inter_right {α : Type u} {s t : set α} (u : set α) (H : s t) :
u s u t
theorem set.union_inter_cancel_left {α : Type u} {s t : set α} :
(s t) s = s
theorem set.union_inter_cancel_right {α : Type u} {s t : set α} :
(s t) t = t

Distributivity laws #

theorem set.inter_distrib_left {α : Type u} (s t u : set α) :
s (t u) = s t s u
theorem set.inter_union_distrib_left {α : Type u} {s t u : set α} :
s (t u) = s t s u
theorem set.inter_distrib_right {α : Type u} (s t u : set α) :
(s t) u = s u t u
theorem set.union_inter_distrib_right {α : Type u} {s t u : set α} :
(s t) u = s u t u
theorem set.union_distrib_left {α : Type u} (s t u : set α) :
s t u = (s t) (s u)
theorem set.union_inter_distrib_left {α : Type u} {s t u : set α} :
s t u = (s t) (s u)
theorem set.union_distrib_right {α : Type u} (s t u : set α) :
s t u = (s u) (t u)
theorem set.inter_union_distrib_right {α : Type u} {s t u : set α} :
s t u = (s u) (t u)
theorem set.union_union_distrib_left {α : Type u} (s t u : set α) :
s (t u) = s t (s u)
theorem set.union_union_distrib_right {α : Type u} (s t u : set α) :
s t u = s u (t u)
theorem set.inter_inter_distrib_left {α : Type u} (s t u : set α) :
s (t u) = s t (s u)
theorem set.inter_inter_distrib_right {α : Type u} (s t u : set α) :
s t u = s u (t u)
theorem set.union_union_union_comm {α : Type u} (s t u v : set α) :
s t (u v) = s u (t v)
theorem set.inter_inter_inter_comm {α : Type u} (s t u v : set α) :
s t (u v) = s u (t v)

Lemmas about insert #

insert α s is the set {α} ∪ s.

theorem set.insert_def {α : Type u} (x : α) (s : set α) :
has_insert.insert x s = {y : α | y = x y s}
@[simp]
theorem set.subset_insert {α : Type u} (x : α) (s : set α) :
theorem set.mem_insert {α : Type u} (x : α) (s : set α) :
theorem set.mem_insert_of_mem {α : Type u} {x : α} {s : set α} (y : α) :
theorem set.eq_or_mem_of_mem_insert {α : Type u} {x a : α} {s : set α} :
theorem set.mem_of_mem_insert_of_ne {α : Type u} {a b : α} {s : set α} :
theorem set.eq_of_not_mem_of_mem_insert {α : Type u} {a b : α} {s : set α} :
@[simp]
theorem set.mem_insert_iff {α : Type u} {x a : α} {s : set α} :
@[simp]
theorem set.insert_eq_of_mem {α : Type u} {a : α} {s : set α} (h : a s) :
theorem set.ne_insert_of_not_mem {α : Type u} {s : set α} (t : set α) {a : α} :
@[simp]
theorem set.insert_eq_self {α : Type u} {a : α} {s : set α} :
theorem set.insert_ne_self {α : Type u} {a : α} {s : set α} :
theorem set.insert_subset {α : Type u} {a : α} {s t : set α} :
theorem set.insert_subset_insert {α : Type u} {a : α} {s t : set α} (h : s t) :
theorem set.insert_subset_insert_iff {α : Type u} {a : α} {s t : set α} (ha : a s) :
theorem set.ssubset_iff_insert {α : Type u} {s t : set α} :
s t (a : α) (H : a s), has_insert.insert a s t
theorem set.ssubset_insert {α : Type u} {s : set α} {a : α} (h : a s) :
theorem set.insert_comm {α : Type u} (a b : α) (s : set α) :
@[simp]
theorem set.insert_idem {α : Type u} (a : α) (s : set α) :
theorem set.insert_union {α : Type u} {a : α} {s t : set α} :
@[simp]
theorem set.union_insert {α : Type u} {a : α} {s t : set α} :
@[simp]
theorem set.insert_nonempty {α : Type u} (a : α) (s : set α) :
@[protected, instance]
def set.has_insert.insert.nonempty {α : Type u} (a : α) (s : set α) :
theorem set.insert_inter_distrib {α : Type u} (a : α) (s t : set α) :
theorem set.insert_union_distrib {α : Type u} (a : α) (s t : set α) :
theorem set.insert_inj {α : Type u} {a b : α} {s : set α} (ha : a s) :
theorem set.forall_of_forall_insert {α : Type u} {P : α Prop} {a : α} {s : set α} (H : (x : α), x has_insert.insert a s P x) (x : α) (h : x s) :
P x
theorem set.forall_insert_of_forall {α : Type u} {P : α Prop} {a : α} {s : set α} (H : (x : α), x s P x) (ha : P a) (x : α) (h : x has_insert.insert a s) :
P x
theorem set.bex_insert_iff {α : Type u} {P : α Prop} {a : α} {s : set α} :
( (x : α) (H : x has_insert.insert a s), P x) P a (x : α) (H : x s), P x
theorem set.ball_insert_iff {α : Type u} {P : α Prop} {a : α} {s : set α} :
( (x : α), x has_insert.insert a s P x) P a (x : α), x s P x

Lemmas about singletons #

theorem set.singleton_def {α : Type u} (a : α) :
{a} = {a}
@[simp]
theorem set.mem_singleton_iff {α : Type u} {a b : α} :
a {b} a = b
@[simp]
theorem set.set_of_eq_eq_singleton {α : Type u} {a : α} :
{n : α | n = a} = {a}
@[simp]
theorem set.set_of_eq_eq_singleton' {α : Type u} {a : α} :
{x : α | a = x} = {a}
@[simp]
theorem set.mem_singleton {α : Type u} (a : α) :
a {a}
theorem set.eq_of_mem_singleton {α : Type u} {x y : α} (h : x {y}) :
x = y
@[simp]
theorem set.singleton_eq_singleton_iff {α : Type u} {x y : α} :
{x} = {y} x = y
theorem set.mem_singleton_of_eq {α : Type u} {x y : α} (H : x = y) :
x {y}
theorem set.insert_eq {α : Type u} (x : α) (s : set α) :
@[simp]
theorem set.singleton_nonempty {α : Type u} (a : α) :
@[simp]
theorem set.singleton_ne_empty {α : Type u} (a : α) :
{a}
@[simp]
theorem set.empty_ssubset_singleton {α : Type u} {a : α} :
{a}
@[simp]
theorem set.singleton_subset_iff {α : Type u} {a : α} {s : set α} :
{a} s a s
theorem set.set_compr_eq_eq_singleton {α : Type u} {a : α} :
{b : α | b = a} = {a}
@[simp]
theorem set.singleton_union {α : Type u} {a : α} {s : set α} :
@[simp]
theorem set.union_singleton {α : Type u} {a : α} {s : set α} :
@[simp]
theorem set.singleton_inter_nonempty {α : Type u} {a : α} {s : set α} :
({a} s).nonempty a s
@[simp]
theorem set.inter_singleton_nonempty {α : Type u} {a : α} {s : set α} :
(s {a}).nonempty a s
@[simp]
theorem set.singleton_inter_eq_empty {α : Type u} {a : α} {s : set α} :
{a} s = a s
@[simp]
theorem set.inter_singleton_eq_empty {α : Type u} {a : α} {s : set α} :
s {a} = a s
theorem set.nmem_singleton_empty {α : Type u} {s : set α} :
@[protected, instance]
def set.unique_singleton {α : Type u} (a : α) :
Equations
theorem set.eq_singleton_iff_unique_mem {α : Type u} {a : α} {s : set α} :
s = {a} a s (x : α), x s x = a
theorem set.eq_singleton_iff_nonempty_unique_mem {α : Type u} {a : α} {s : set α} :
s = {a} s.nonempty (x : α), x s x = a
@[simp]
theorem set.default_coe_singleton {α : Type u} (x : α) :

Lemmas about pairs #

@[simp]
theorem set.pair_eq_singleton {α : Type u} (a : α) :
{a, a} = {a}
theorem set.pair_comm {α : Type u} (a b : α) :
{a, b} = {b, a}
theorem set.pair_eq_pair_iff {α : Type u} {x y z w : α} :
{x, y} = {z, w} x = z y = w x = w y = z

Lemmas about sets defined as {x ∈ s | p x}. #

theorem set.mem_sep {α : Type u} {s : set α} {p : α Prop} {x : α} (xs : x s) (px : p x) :
x {x ∈ s | p x}
@[simp]
theorem set.sep_mem_eq {α : Type u} {s t : set α} :
{x ∈ s | x t} = s t
@[simp]
theorem set.mem_sep_iff {α : Type u} {s : set α} {p : α Prop} {x : α} :
x {x ∈ s | p x} x s p x
theorem set.sep_ext_iff {α : Type u} {s : set α} {p q : α Prop} :
{x ∈ s | p x} = {x ∈ s | q x} (x : α), x s (p x q x)
theorem set.sep_eq_of_subset {α : Type u} {s t : set α} (h : s t) :
{x ∈ t | x s} = s
@[simp]
theorem set.sep_subset {α : Type u} (s : set α) (p : α Prop) :
{x ∈ s | p x} s
@[simp]
theorem set.sep_eq_self_iff_mem_true {α : Type u} {s : set α} {p : α Prop} :
{x ∈ s | p x} = s (x : α), x s p x
@[simp]
theorem set.sep_eq_empty_iff_mem_false {α : Type u} {s : set α} {p : α Prop} :
{x ∈ s | p x} = (x : α), x s ¬p x
@[simp]
theorem set.sep_true {α : Type u} {s : set α} :
{x ∈ s | true} = s
@[simp]
theorem set.sep_false {α : Type u} {s : set α} :
{x ∈ s | false} =
@[simp]
theorem set.sep_empty {α : Type u} (p : α Prop) :
{x ∈ | p x} =
@[simp]
theorem set.sep_univ {α : Type u} {p : α Prop} :
{x ∈ set.univ | p x} = {x : α | p x}
@[simp]
theorem set.sep_union {α : Type u} {s t : set α} {p : α Prop} :
{x ∈ s t | p x} = {x ∈ s | p x} {x ∈ t | p x}
@[simp]
theorem set.sep_inter {α : Type u} {s t : set α} {p : α Prop} :
{x ∈ s t | p x} = {x ∈ s | p x} {x ∈ t | p x}
@[simp]
theorem set.sep_and {α : Type u} {s : set α} {p q : α Prop} :
{x ∈ s | p x q x} = {x ∈ s | p x} {x ∈ s | q x}
@[simp]
theorem set.sep_or {α : Type u} {s : set α} {p q : α Prop} :
{x ∈ s | p x q x} = {x ∈ s | p x} {x ∈ s | q x}
@[simp]
theorem set.sep_set_of {α : Type u} {p q : α Prop} :
{x ∈ {y : α | p y} | q x} = {x : α | p x q x}
@[simp]
theorem set.subset_singleton_iff {α : Type u_1} {s : set α} {x : α} :
s {x} (y : α), y s y = x
theorem set.subset_singleton_iff_eq {α : Type u} {s : set α} {x : α} :
s {x} s = s = {x}
theorem set.nonempty.subset_singleton_iff {α : Type u} {a : α} {s : set α} (h : s.nonempty) :
s {a} s = {a}
theorem set.ssubset_singleton_iff {α : Type u} {s : set α} {x : α} :
s {x} s =
theorem set.eq_empty_of_ssubset_singleton {α : Type u} {s : set α} {x : α} (hs : s {x}) :
s =

Disjointness #

@[protected]
theorem set.disjoint_iff {α : Type u} {s t : set α} :
theorem set.disjoint_iff_inter_eq_empty {α : Type u} {s t : set α} :
disjoint s t s t =
theorem disjoint.inter_eq {α : Type u} {s t : set α} :
disjoint s t s t =
theorem set.disjoint_left {α : Type u} {s t : set α} :
disjoint s t ⦃a : α⦄, a s a t
theorem set.disjoint_right {α : Type u} {s t : set α} :
disjoint s t ⦃a : α⦄, a t a s
theorem set.not_disjoint_iff {α : Type u} {s t : set α} :
¬disjoint s t (x : α), x s x t
theorem set.not_disjoint_iff_nonempty_inter {α : Type u} {s t : set α} :
theorem set.nonempty.not_disjoint {α : Type u} {s t : set α} :

Alias of the reverse direction of set.not_disjoint_iff_nonempty_inter.

theorem set.disjoint_or_nonempty_inter {α : Type u} (s t : set α) :
theorem set.disjoint_iff_forall_ne {α : Type u} {s t : set α} :
disjoint s t (x : α), x s (y : α), y t x y
theorem disjoint.ne_of_mem {α : Type u} {s t : set α} (h : disjoint s t) {x y : α} (hx : x s) (hy : y t) :
x y
theorem set.disjoint_of_subset_left {α : Type u} {s₁ s₂ t : set α} (hs : s₁ s₂) (h : disjoint s₂ t) :
disjoint s₁ t
theorem set.disjoint_of_subset_right {α : Type u} {s t₁ t₂ : set α} (ht : t₁ t₂) (h : disjoint s t₂) :
disjoint s t₁
theorem set.disjoint_of_subset {α : Type u} {s₁ s₂ t₁ t₂ : set α} (hs : s₁ s₂) (ht : t₁ t₂) (h : disjoint s₂ t₂) :
disjoint s₁ t₁
@[simp]
theorem set.disjoint_union_left {α : Type u} {s t u : set α} :
@[simp]
theorem set.disjoint_union_right {α : Type u} {s t u : set α} :
@[simp]
theorem set.disjoint_empty {α : Type u} (s : set α) :
@[simp]
theorem set.empty_disjoint {α : Type u} (s : set α) :
@[simp]
theorem set.univ_disjoint {α : Type u} {s : set α} :
@[simp]
theorem set.disjoint_univ {α : Type u} {s : set α} :
theorem set.disjoint_sdiff_left {α : Type u} {s t : set α} :
disjoint (t \ s) s
theorem set.disjoint_sdiff_right {α : Type u} {s t : set α} :
disjoint s (t \ s)
@[simp]
theorem set.disjoint_singleton_left {α : Type u} {a : α} {s : set α} :
disjoint {a} s a s
@[simp]
theorem set.disjoint_singleton_right {α : Type u} {a : α} {s : set α} :
disjoint s {a} a s
@[simp]
theorem set.disjoint_singleton {α : Type u} {a b : α} :
disjoint {a} {b} a b
theorem set.subset_diff {α : Type u} {s t u : set α} :
s t \ u s t disjoint s u

Lemmas about complement #

theorem set.compl_def {α : Type u} (s : set α) :
s = {x : α | x s}
theorem set.mem_compl {α : Type u} {s : set α} {x : α} (h : x s) :
x s
theorem set.compl_set_of {α : Type u_1} (p : α Prop) :
{a : α | p a} = {a : α | ¬p a}
theorem set.not_mem_of_mem_compl {α : Type u} {s : set α} {x : α} (h : x s) :
x s
@[simp]
theorem set.mem_compl_iff {α : Type u} (s : set α) (x : α) :
x s x s
theorem set.not_mem_compl_iff {α : Type u} {s : set α} {x : α} :
x s x s
@[simp]
theorem set.inter_compl_self {α : Type u} (s : set α) :
@[simp]
theorem set.compl_inter_self {α : Type u} (s : set α) :
@[simp]
theorem set.compl_empty {α : Type u} :
@[simp]
theorem set.compl_union {α : Type u} (s t : set α) :
(s t) = s t
theorem set.compl_inter {α : Type u} (s t : set α) :
(s t) = s t
@[simp]
theorem set.compl_univ {α : Type u} :
@[simp]
theorem set.compl_empty_iff {α : Type u} {s : set α} :
@[simp]
theorem set.compl_univ_iff {α : Type u} {s : set α} :
theorem set.compl_ne_univ {α : Type u} {s : set α} :
theorem set.nonempty_compl {α : Type u} {s : set α} :
theorem set.mem_compl_singleton_iff {α : Type u} {a x : α} :
x {a} x a
theorem set.compl_singleton_eq {α : Type u} (a : α) :
{a} = {x : α | x a}
@[simp]
theorem set.compl_ne_eq_singleton {α : Type u} (a : α) :
{x : α | x a} = {a}
theorem set.union_eq_compl_compl_inter_compl {α : Type u} (s t : set α) :
s t = (s t)
theorem set.inter_eq_compl_compl_union_compl {α : Type u} (s t : set α) :
s t = (s t)
@[simp]
theorem set.union_compl_self {α : Type u} (s : set α) :
@[simp]
theorem set.compl_union_self {α : Type u} (s : set α) :
theorem set.compl_subset_comm {α : Type u} {s t : set α} :
s t t s
theorem set.subset_compl_comm {α : Type u} {s t : set α} :
s t t s
@[simp]
theorem set.compl_subset_compl {α : Type u} {s t : set α} :
s t t s
theorem set.subset_compl_iff_disjoint_left {α : Type u} {s t : set α} :
theorem set.subset_compl_iff_disjoint_right {α : Type u} {s t : set α} :
theorem set.disjoint_compl_left_iff_subset {α : Type u} {s t : set α} :
theorem set.disjoint_compl_right_iff_subset {α : Type u} {s t : set α} :
theorem disjoint.subset_compl_right {α : Type u} {s t : set α} :

Alias of the reverse direction of set.subset_compl_iff_disjoint_right.

theorem disjoint.subset_compl_left {α : Type u} {s t : set α} :

Alias of the reverse direction of set.subset_compl_iff_disjoint_left.

theorem has_subset.subset.disjoint_compl_left {α : Type u} {s t : set α} :

Alias of the reverse direction of set.disjoint_compl_left_iff_subset.

theorem has_subset.subset.disjoint_compl_right {α : Type u} {s t : set α} :

Alias of the reverse direction of set.disjoint_compl_right_iff_subset.

theorem set.subset_union_compl_iff_inter_subset {α : Type u} {s t u : set α} :
s t u s u t
theorem set.compl_subset_iff_union {α : Type u} {s t : set α} :
@[simp]
theorem set.subset_compl_singleton_iff {α : Type u} {a : α} {s : set α} :
s {a} a s
theorem set.inter_subset {α : Type u} (a b c : set α) :
a b c a b c
theorem set.inter_compl_nonempty_iff {α : Type u} {s t : set α} :

Lemmas about set difference #

theorem set.diff_eq {α : Type u} (s t : set α) :
s \ t = s t
@[simp]
theorem set.mem_diff {α : Type u} {s t : set α} (x : α) :
x s \ t x s x t
theorem set.mem_diff_of_mem {α : Type u} {s t : set α} {x : α} (h1 : x s) (h2 : x t) :
x s \ t
theorem set.not_mem_diff_of_mem {α : Type u} {s t : set α} {x : α} (hx : x t) :
x s \ t
theorem set.mem_of_mem_diff {α : Type u} {s t : set α} {x : α} (h : x s \ t) :
x s
theorem set.not_mem_of_mem_diff {α : Type u} {s t : set α} {x : α} (h : x s \ t) :
x t
theorem set.diff_eq_compl_inter {α : Type u} {s t : set α} :
s \ t = t s
theorem set.nonempty_diff {α : Type u} {s t : set α} :
(s \ t).nonempty ¬s t
theorem set.diff_subset {α : Type u} (s t : set α) :
s \ t s
theorem set.union_diff_cancel' {α : Type u} {s t u : set α} (h₁ : s t) (h₂ : t u) :
t u \ s = u
theorem set.union_diff_cancel {α : Type u} {s t : set α} (h : s t) :
s t \ s = t
theorem set.union_diff_cancel_left {α : Type u} {s t : set α} (h : s t ) :
(s t) \ s = t
theorem set.union_diff_cancel_right {α : Type u} {s t : set α} (h : s t ) :
(s t) \ t = s
@[simp]
theorem set.union_diff_left {α : Type u} {s t : set α} :
(s t) \ s = t \ s
@[simp]
theorem set.union_diff_right {α : Type u} {s t : set α} :
(s t) \ t = s \ t
theorem set.union_diff_distrib {α : Type u} {s t u : set α} :
(s t) \ u = s \ u t \ u
theorem set.inter_diff_assoc {α : Type u} (a b c : set α) :
a b \ c = a (b \ c)
@[simp]
theorem set.inter_diff_self {α : Type u} (a b : set α) :
a (b \ a) =
@[simp]
theorem set.inter_union_diff {α : Type u} (s t : set α) :
s t s \ t = s
@[simp]
theorem set.diff_union_inter {α : Type u} (s t : set α) :
s \ t s t = s
@[simp]
theorem set.inter_union_compl {α : Type u} (s t : set α) :
s t s t = s
theorem set.diff_subset_diff {α : Type u} {s₁ s₂ t₁ t₂ : set α} :
s₁ s₂ t₂ t₁ s₁ \ t₁ s₂ \ t₂
theorem set.diff_subset_diff_left {α : Type u} {s₁ s₂ t : set α} (h : s₁ s₂) :
s₁ \ t s₂ \ t
theorem set.diff_subset_diff_right {α : Type u} {s t u : set α} (h : t u) :
s \ u s \ t
theorem set.compl_eq_univ_diff {α : Type u} (s : set α) :
@[simp]
theorem set.empty_diff {α : Type u} (s : set α) :
theorem set.diff_eq_empty {α : Type u} {s t : set α} :
s \ t = s t
@[simp]
theorem set.diff_empty {α : Type u} {s : set α} :
s \ = s
@[simp]
theorem set.diff_univ {α : Type u} (s : set α) :
theorem set.diff_diff {α : Type u} {s t u : set α} :
s \ t \ u = s \ (t u)
theorem set.diff_diff_comm {α : Type u} {s t u : set α} :
s \ t \ u = s \ u \ t
theorem set.diff_subset_iff {α : Type u} {s t u : set α} :
s \ t u s t u
theorem set.subset_diff_union {α : Type u} (s t : set α) :
s s \ t t
theorem set.diff_union_of_subset {α : Type u} {s t : set α} (h : t s) :
s \ t t = s
@[simp]
theorem set.diff_singleton_subset_iff {α : Type u} {x : α} {s t : set α} :
s \ {x} t s has_insert.insert x t
theorem set.subset_diff_singleton {α : Type u} {x : α} {s t : set α} (h : s t) (hx : x s) :
s t \ {x}
theorem set.subset_insert_diff_singleton {α : Type u} (x : α) (s : set α) :
s has_insert.insert x (s \ {x})
theorem set.diff_subset_comm {α : Type u} {s t u : set α} :
s \ t u s \ u t
theorem set.diff_inter {α : Type u} {s t u : set α} :
s \ (t u) = s \ t s \ u
theorem set.diff_inter_diff {α : Type u} {s t u : set α} :
s \ t (s \ u) = s \ (t u)
theorem set.diff_compl {α : Type u} {s t : set α} :
s \ t = s t
theorem set.diff_diff_right {α : Type u} {s t u : set α} :
s \ (t \ u) = s \ t s u
@[simp]
theorem set.insert_diff_of_mem {α : Type u} {a : α} {t : set α} (s : set α) (h : a t) :
theorem set.insert_diff_of_not_mem {α : Type u} {a : α} {t : set α} (s : set α) (h : a t) :
theorem set.insert_diff_self_of_not_mem {α : Type u} {a : α} {s : set α} (h : a s) :
@[simp]
theorem set.insert_diff_eq_singleton {α : Type u} {a : α} {s : set α} (h : a s) :
theorem set.inter_insert_of_mem {α : Type u} {a : α} {s t : set α} (h : a s) :
theorem set.insert_inter_of_mem {α : Type u} {a : α} {s t : set α} (h : a t) :
theorem set.inter_insert_of_not_mem {α : Type u} {a : α} {s t : set α} (h : a s) :
theorem set.insert_inter_of_not_mem {α : Type u} {a : α} {s t : set α} (h : a t) :
@[simp]
theorem set.union_diff_self {α : Type u} {s t : set α} :
s t \ s = s t
@[simp]
theorem set.diff_union_self {α : Type u} {s t : set α} :
s \ t t = s t
@[simp]
theorem set.diff_inter_self {α : Type u} {a b : set α} :
b \ a a =
@[simp]
theorem set.diff_inter_self_eq_diff {α : Type u} {s t : set α} :
s \ (t s) = s \ t
@[simp]
theorem set.diff_self_inter {α : Type u} {s t : set α} :
s \ (s t) = s \ t
@[simp]
theorem set.diff_singleton_eq_self {α : Type u} {a : α} {s : set α} (h : a s) :
s \ {a} = s
@[simp]
theorem set.insert_diff_singleton {α : Type u} {a : α} {s : set α} :
@[simp]
theorem set.diff_self {α : Type u} {s : set α} :
s \ s =
theorem set.diff_diff_right_self {α : Type u} (s t : set α) :
s \ (s \ t) = s t
theorem set.diff_diff_cancel_left {α : Type u} {s t : set α} (h : s t) :
t \ (t \ s) = s
theorem set.mem_diff_singleton {α : Type u} {x y : α} {s : set α} :
x s \ {y} x s x y
theorem set.mem_diff_singleton_empty {α : Type u} {s : set α} {t : set (set α)} :
s t \ {} s t s.nonempty
theorem set.union_eq_diff_union_diff_union_inter {α : Type u} (s t : set α) :
s t = s \ t t \ s s t

Symmetric difference #

theorem set.mem_symm_diff {α : Type u} {a : α} {s t : set α} :
a s t a s a t a t a s
@[protected]
theorem set.symm_diff_def {α : Type u} (s t : set α) :
s t = s \ t t \ s
theorem set.symm_diff_subset_union {α : Type u} {s t : set α} :
s t s t
@[simp]
theorem set.symm_diff_eq_empty {α : Type u} {s t : set α} :
s t = s = t
@[simp]
theorem set.symm_diff_nonempty {α : Type u} {s t : set α} :
(s t).nonempty s t
theorem set.inter_symm_diff_distrib_left {α : Type u} (s t u : set α) :
s t u = (s t) (s u)
theorem set.inter_symm_diff_distrib_right {α : Type u} (s t u : set α) :
s t u = (s u) (t u)
theorem set.subset_symm_diff_union_symm_diff_left {α : Type u} {s t u : set α} (h : disjoint s t) :
u s u t u
theorem set.subset_symm_diff_union_symm_diff_right {α : Type u} {s t u : set α} (h : disjoint t u) :
s s t s u

Powerset #

def set.powerset {α : Type u} (s : set α) :
set (set α)

𝒫 s = set.powerset s is the set of all subsets of s.

Equations
theorem set.mem_powerset {α : Type u} {x s : set α} (h : x s) :
theorem set.subset_of_mem_powerset {α : Type u} {x s : set α} (h : x 𝒫s) :
x s
@[simp]
theorem set.mem_powerset_iff {α : Type u} (x s : set α) :
x 𝒫s x s
theorem set.powerset_inter {α : Type u} (s t : set α) :
@[simp]
theorem set.powerset_mono {α : Type u} {s t : set α} :
@[simp]
theorem set.powerset_nonempty {α : Type u} {s : set α} :
@[simp]
theorem set.powerset_empty {α : Type u} :
@[simp]

Sets defined as an if-then-else #

theorem set.mem_dite_univ_right {α : Type u} (p : Prop) [decidable p] (t : p set α) (x : α) :
x dite p (λ (h : p), t h) (λ (h : ¬p), set.univ) (h : p), x t h
@[simp]
theorem set.mem_ite_univ_right {α : Type u} (p : Prop) [decidable p] (t : set α) (x : α) :
x ite p t set.univ p x t
theorem set.mem_dite_univ_left {α : Type u} (p : Prop) [decidable p] (t : ¬p set α) (x : α) :
x dite p (λ (h : p), set.univ) (λ (h : ¬p), t h) (h : ¬p), x t h
@[simp]
theorem set.mem_ite_univ_left {α : Type u} (p : Prop) [decidable p] (t : set α) (x : α) :
x ite p set.univ t ¬p x t
theorem set.mem_dite_empty_right {α : Type u} (p : Prop) [decidable p] (t : p set α) (x : α) :
x dite p (λ (h : p), t h) (λ (h : ¬p), ) (h : p), x t h
@[simp]
theorem set.mem_ite_empty_right {α : Type u} (p : Prop) [decidable p] (t : set α) (x : α) :
x ite p t p x t
theorem set.mem_dite_empty_left {α : Type u} (p : Prop) [decidable p] (t : ¬p set α) (x : α) :
x dite p (λ (h : p), ) (λ (h : ¬p), t h) (h : ¬p), x t h
@[simp]
theorem set.mem_ite_empty_left {α : Type u} (p : Prop) [decidable p] (t : set α) (x : α) :
x ite p t ¬p x t

If-then-else for sets #

@[protected]
def set.ite {α : Type u} (t s s' : set α) :
set α

ite for sets: set.ite t s s' ∩ t = s ∩ t, set.ite t s s' ∩ tᶜ = s' ∩ tᶜ. Defined as s ∩ t ∪ s' \ t.

Equations
@[simp]
theorem set.ite_inter_self {α : Type u} (t s s' : set α) :
t.ite s s' t = s t
@[simp]
theorem set.ite_compl {α : Type u} (t s s' : set α) :
t.ite s s' = t.ite s' s
@[simp]
theorem set.ite_inter_compl_self {α : Type u} (t s s' : set α) :
t.ite s s' t = s' t
@[simp]
theorem set.ite_diff_self {α : Type u} (t s s' : set α) :
t.ite s s' \ t = s' \ t
@[simp]
theorem set.ite_same {α : Type u} (t s : set α) :
t.ite s s = s
@[simp]
theorem set.ite_left {α : Type u} (s t : set α) :
s.ite s t = s t
@[simp]
theorem set.ite_right {α : Type u} (s t : set α) :
s.ite t s = t s
@[simp]
theorem set.ite_empty {α : Type u} (s s' : set α) :
.ite s s' = s'
@[simp]
theorem set.ite_univ {α : Type u} (s s' : set α) :
set.univ.ite s s' = s
@[simp]
theorem set.ite_empty_left {α : Type u} (t s : set α) :
t.ite s = s \ t
@[simp]
theorem set.ite_empty_right {α : Type u} (t s : set α) :
t.ite s = s t
theorem set.ite_mono {α : Type u} (t : set α) {s₁ s₁' s₂ s₂' : set α} (h : s₁ s₂) (h' : s₁' s₂') :
t.ite s₁ s₁' t.ite s₂ s₂'
theorem set.ite_subset_union {α : Type u} (t s s' : set α) :
t.ite s s' s s'
theorem set.inter_subset_ite {α : Type u} (t s s' : set α) :
s s' t.ite s s'
theorem set.ite_inter_inter {α : Type u} (t s₁ s₂ s₁' s₂' : set α) :
t.ite (s₁ s₂) (s₁' s₂') = t.ite s₁ s₁' t.ite s₂ s₂'
theorem set.ite_inter {α : Type u} (t s₁ s₂ s : set α) :
t.ite (s₁ s) (s₂ s) = t.ite s₁ s₂ s
theorem set.ite_inter_of_inter_eq {α : Type u} (t : set α) {s₁ s₂ s : set α} (h : s₁ s = s₂ s) :
t.ite s₁ s₂ s = s₁ s
theorem set.subset_ite {α : Type u} {t s s' u : set α} :
u t.ite s s' u t s u \ t s'

Subsingleton #

@[protected]
def set.subsingleton {α : Type u} (s : set α) :
Prop

A set s is a subsingleton if it has at most one element.

Equations
theorem set.subsingleton.anti {α : Type u} {s t : set α} (ht : t.subsingleton) (hst : s t) :
theorem set.subsingleton.eq_singleton_of_mem {α : Type u} {s : set α} (hs : s.subsingleton) {x : α} (hx : x s) :
s = {x}
@[simp]
@[simp]
theorem set.subsingleton_singleton {α : Type u} {a : α} :
theorem set.subsingleton_of_subset_singleton {α : Type u} {a : α} {s : set α} (h : s {a}) :
theorem set.subsingleton_of_forall_eq {α : Type u} {s : set α} (a : α) (h : (b : α), b s b = a) :
theorem set.subsingleton_iff_singleton {α : Type u} {s : set α} {x : α} (hx : x s) :
theorem set.subsingleton.eq_empty_or_singleton {α : Type u} {s : set α} (hs : s.subsingleton) :
s = (x : α), s = {x}
theorem set.subsingleton.induction_on {α : Type u} {s : set α} {p : set α Prop} (hs : s.subsingleton) (he : p ) (h₁ : (x : α), p {x}) :
p s
theorem set.subsingleton_is_top (α : Type u_1) [partial_order α] :
{x : α | is_top x}.subsingleton
theorem set.subsingleton_is_bot (α : Type u_1) [partial_order α] :
{x : α | is_bot x}.subsingleton
@[simp, norm_cast]
theorem set.subsingleton_coe {α : Type u} (s : set α) :

s, coerced to a type, is a subsingleton type if and only if s is a subsingleton set.

@[protected, instance]

The coe_sort of a set s in a subsingleton type is a subsingleton. For the corresponding result for subtype, see subtype.subsingleton.

Nontrivial #

@[protected]
def set.nontrivial {α : Type u} (s : set α) :
Prop

A set s is nontrivial if it has at least two distinct elements.

Equations
theorem set.nontrivial_of_mem_mem_ne {α : Type u} {s : set α} {x y : α} (hx : x s) (hy : y s) (hxy : x y) :
@[protected]
noncomputable def set.nontrivial.some {α : Type u} {s : set α} (hs : s.nontrivial) :
α × α

Extract witnesses from s.nontrivial. This function might be used instead of case analysis on the argument. Note that it makes a proof depend on the classical.choice axiom.

Equations
@[protected]
theorem set.nontrivial.some_fst_mem {α : Type u} {s : set α} (hs : s.nontrivial) :
hs.some.fst s
@[protected]
theorem set.nontrivial.some_snd_mem {α : Type u} {s : set α} (hs : s.nontrivial) :
hs.some.snd s
@[protected]
theorem set.nontrivial.some_fst_ne_some_snd {α : Type u} {s : set α} (hs : s.nontrivial) :
theorem set.nontrivial.mono {α : Type u} {s t : set α} (hs : s.nontrivial) (hst : s t) :
theorem set.nontrivial_pair {α : Type u} {x y : α} (hxy : x y) :
{x, y}.nontrivial
theorem set.nontrivial_of_pair_subset {α : Type u} {s : set α} {x y : α} (hxy : x y) (h : {x, y} s) :
theorem set.nontrivial.pair_subset {α : Type u} {s : set α} (hs : s.nontrivial) :
(x y : α) (hab : x y), {x, y} s
theorem set.nontrivial_iff_pair_subset {α : Type u} {s : set α} :
s.nontrivial (x y : α) (hxy : x y), {x, y} s
theorem set.nontrivial_of_exists_ne {α : Type u} {s : set α} {x : α} (hx : x s) (h : (y : α) (H : y s), y x) :
theorem set.nontrivial.exists_ne {α : Type u} {s : set α} (hs : s.nontrivial) (z : α) :
(x : α) (H : x s), x z
theorem set.nontrivial_iff_exists_ne {α : Type u} {s : set α} {x : α} (hx : x s) :
s.nontrivial (y : α) (H : y s), y x
theorem set.nontrivial_of_lt {α : Type u} {s : set α} [preorder α] {x y : α} (hx : x s) (hy : y s) (hxy : x < y) :
theorem set.nontrivial_of_exists_lt {α : Type u} {s : set α} [preorder α] (H : (x : α) (H : x s) (y : α) (H : y s), x < y) :
theorem set.nontrivial.exists_lt {α : Type u} {s : set α} [linear_order α] (hs : s.nontrivial) :
(x : α) (H : x s) (y : α) (H : y s), x < y
theorem set.nontrivial_iff_exists_lt {α : Type u} {s : set α} [linear_order α] :
s.nontrivial (x : α) (H : x s) (y : α) (H : y s), x < y
@[protected]
theorem set.nontrivial.nonempty {α : Type u} {s : set α} (hs : s.nontrivial) :
@[protected]
theorem set.nontrivial.ne_empty {α : Type u} {s : set α} (hs : s.nontrivial) :
theorem set.nontrivial.not_subset_empty {α : Type u} {s : set α} (hs : s.nontrivial) :
@[simp]
@[simp]
theorem set.not_nontrivial_singleton {α : Type u} {x : α} :
theorem set.nontrivial.ne_singleton {α : Type u} {s : set α} {x : α} (hs : s.nontrivial) :
s {x}
theorem set.nontrivial.not_subset_singleton {α : Type u} {s : set α} {x : α} (hs : s.nontrivial) :
¬s {x}
theorem set.nontrivial_of_nontrivial {α : Type u} {s : set α} (hs : s.nontrivial) :