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Theorems · Theorem · order theory

GaloisConnection.le_u_l_trans

∀ {α : Type u} {β : Type v} [inst : Preorder α] [inst_1 : Preorder β] {l : α → β} {u : β → α},
  GaloisConnection l u → ∀ {x y z : α}, x ≤ u (l y) → y ≤ u (l z) → x ≤ u (l z)

If (l, u) is a Galois connection, then the relation x ≤ u (l y) is a transitive relation. If l is a closure operator (Submodule.span, Subgroup.closure, ...) and u is the coercion to Set, this reads as "if U is in the closure of V and V is in the closure of W then U is in the closure of W".

Defined in
Mathlib.Order.GaloisConnection.Defs
Cited by
2 results in Mathlib
Foundations
Depth 10 from the axioms · uses propext, Quot.sound
Assumes
PreorderPreorder

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