theorem Partition.IsPartition.nonempty_not_mem {α : Type u_1} {t : Set α} {S : Set (Set α)} (hS : IsPartition S) (hx : t ∈ S) :
t.Nonempty
theorem Partition.IsPartition.empty_not_mem {α : Type u_1} {S : Set (Set α)} (hS : IsPartition S) :
∅ ∉ S
Every partition of s : Set α induces a transitive, symmetric Binary relation on α
whose equivalence classes are the parts of P. The relation is irreflexive outside s.
Instances For
@[instance_reducible]
Equations
- Partition.instFunLikeSetForallProp = { coe := Partition.Rel, coe_injective := ⋯ }
theorem Partition.Rel.trans {α : Type u_1} {x y z : α} {P : Partition (Set α)} (hxy : P x y) (hyz : P y z) :
P x z
@[simp]
@[simp]
theorem Partition.rel_le_of_isInducedSubpartition {α : Type u_1} {P Q : Partition (Set α)} (h : P.isInducedSubpartition Q) :
A transitive, symmetric Binary relation r induces a partition of the set of elements on
which it is reflexive.
Equations
- Partition.ofRel r = { parts := Relation.fibers r, indep := ⋯, bot_not_mem := ⋯ }
Instances For
@[simp]
@[simp]
Equations
Instances For
@[simp]
@[simp]
@[simp]
The part containing a given element of the set being partitioned. If x ∉ s, then ∅.
Equations
- P.partOf x = Relation.fiber (⇑P) x
Instances For
@[simp]
theorem Partition.inf_rel_trans {α : Type u_1} {a b c : α} {P Q : Partition (Set α)} (hab : (⇑P ⊓ ⇑Q) a b) (hbc : (⇑P ⊓ ⇑Q) b c) :
(⇑P ⊓ ⇑Q) a c
@[simp]
@[simp]
@[simp]
@[simp]
@[simp]
@[simp]
theorem Partition.discrete_of_le_discrete {α : Type u_5} {S : Set α} {P : Partition (Set α)} (hS : P ≤ Partition.discrete S) :
@[simp]
@[simp]
@[simp]
theorem Partition.discrete_isInducedSubpartition_iff {α : Type u_5} {S : Set α} {Q : Partition (Set α)} :