Notation classes for lattice operations

In this file we introduce typeclasses and definitions for lattice operations.

Main definitions

• HasCompl: type class for the ᶜ notation
• Top: type class for the ⊤ notation
• Bot: type class for the ⊥ notation

Notations

• xᶜ: complement in a lattice;
• x ⊔ y: supremum/join, which is notation for max x y;
• x ⊓ y: infimum/meet, which is notation for min x y;

We implement a delaborator that pretty prints max x y/min x y as x ⊔ y/x ⊓ y if and only if the order on α does not have a LinearOrder α instance (where x y : α).

This is so that in a lattice we can use the same underlying constants max/min as in linear orders, while using the more idiomatic notation x ⊔ y/x ⊓ y. Lemmas about the operators ⊔ and ⊓ should use the names sup and inf respectively.

class HasCompl (α : Type u_1) : Type u_1

Set / lattice complement

• compl : α → α

  Set / lattice complement

def «term_ᶜ» : Lean.TrailingParserDescr

Set / lattice complement

Sup and Inf

theorem Min.ext {α : Type u} {x y : Min α} (min : min = min) : x = y

theorem Max.ext_iff {α : Type u} {x y : Max α} : x = y ↔ max = max

theorem Min.ext_iff {α : Type u} {x y : Min α} : x = y ↔ min = min

theorem Max.ext {α : Type u} {x y : Max α} (max : max = max) : x = y

def «term_⊔_» : Lean.TrailingParserDescr

The supremum/join operation: x ⊔ y. It is notation for max x y and should be used when the type is not a linear order.

def «term_⊓_» : Lean.TrailingParserDescr

The infimum/meet operation: x ⊓ y. It is notation for min x y and should be used when the type is not a linear order.

def Mathlib.Meta.delabSup : Lean.PrettyPrinter.Delaborator.Delab

Delaborate max x y into x ⊔ y if the type is not a linear order.

def Mathlib.Meta.delabInf : Lean.PrettyPrinter.Delaborator.Delab

Delaborate min x y into x ⊓ y if the type is not a linear order.

class HImp (α : Type u_1) : Type u_1

Syntax typeclass for Heyting implication ⇨.

• himp : α → α → α

  Heyting implication ⇨

class HNot (α : Type u_1) : Type u_1

Syntax typeclass for Heyting negation ￢.

The difference between HasCompl and HNot is that the former belongs to Heyting algebras, while the latter belongs to co-Heyting algebras. They are both pseudo-complements, but compl underestimates while HNot overestimates. In boolean algebras, they are equal. See hnot_eq_compl.

• hnot : α → α

  Heyting negation ￢

def «term_⇨_» : Lean.TrailingParserDescr

Heyting implication

def «term￢_» : Lean.ParserDescr

Heyting negation

class Top (α : Type u_1) : Type u_1

Typeclass for the ⊤ (\top) notation

• top : α

  The top (⊤, \top) element

theorem Top.ext_iff {α : Type u_1} {x y : Top α} : x = y ↔ ⊤ = ⊤

theorem Top.ext {α : Type u_1} {x y : Top α} (top : ⊤ = ⊤) : x = y

class Bot (α : Type u_1) : Type u_1

Typeclass for the ⊥ (\bot) notation

• bot : α

  The bot (⊥, \bot) element

theorem Bot.ext_iff {α : Type u_1} {x y : Bot α} : x = y ↔ ⊥ = ⊥

theorem Bot.ext {α : Type u_1} {x y : Bot α} (bot : ⊥ = ⊥) : x = y

def «term⊤» : Lean.ParserDescr

The top (⊤, \top) element

def «term⊥» : Lean.ParserDescr

The bot (⊥, \bot) element

@[instance 100]

instance top_nonempty (α : Type u_1) [Top α] : Nonempty α

@[instance 100]

instance bot_nonempty (α : Type u_1) [Bot α] : Nonempty α