Documentation

Mathlib.Data.Nat.PartENat

Natural numbers with infinity #

The natural numbers and an extra top element ⊤. This implementation uses Part ℕ as an implementation. This version is deprecated, use ℕ∞ instead.

Main definitions #

The following instances are defined:

There is no additive analogue of MonoidWithZero; if there were then PartENat could be an AddMonoidWithTop.

toWithTop : the map from PartENat to ℕ∞, with theorems that it plays well with + and ≤.
withTopAddEquiv : PartENat ≃+ ℕ∞
withTopOrderIso : PartENat ≃o ℕ∞

Implementation details #

PartENat is defined to be Part ℕ.

+ and ≤ are defined on PartENat, but there is an issue with * because it's not clear what 0 * ⊤ should be. mul is hence left undefined. Similarly ⊤ - ⊤ is ambiguous so there is no - defined on PartENat.

Before the open scoped Classical line, various proofs are made with decidability assumptions. This can cause issues -- see for example the non-simp lemma toWithTopZero proved by rfl, followed by @[simp] lemma toWithTopZero' whose proof uses convert.

Deprecation #

As it appears this has been unused since 2018, we are now deprecating it. If ENat does not serve your purposes, please raise this on the community Zulip.

Tags #

PartENat, ℕ∞

@[deprecated ENat (since := "2025-09-01")]

Type of natural numbers with infinity (⊤)

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Instances For

def PartENat.some :

ℕ → PartENat

The computable embedding ℕ → PartENat.

This coincides with the coercion coe : ℕ → PartENat, see PartENat.some_eq_natCast.

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Instances For

instance PartENat.instZero :

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instance PartENat.instInhabited :

Inhabited PartENat

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instance PartENat.instOne :

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instance PartENat.instAdd :

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instance PartENat.instDecidableDomNatSome (n : ℕ) :

Decidable (↑n).Dom

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@[simp]

theorem PartENat.dom_some (x : ℕ) :

(↑x).Dom

instance PartENat.addCommMonoid :

AddCommMonoid PartENat

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instance PartENat.instAddCommMonoidWithOne :

AddCommMonoidWithOne PartENat

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theorem PartENat.some_eq_natCast (n : ℕ) :

↑n = ↑n

instance PartENat.instCharZero :

CharZero PartENat

theorem PartENat.natCast_inj {x y : ℕ} :

↑x = ↑y ↔ x = y

Alias of Nat.cast_inj specialized to PartENat

@[simp]

theorem PartENat.dom_natCast (x : ℕ) :

(↑x).Dom

@[simp]

theorem PartENat.dom_ofNat (x : ℕ) [x.AtLeastTwo] :

(OfNat.ofNat x).Dom

@[simp]

theorem PartENat.dom_zero :

@[simp]

theorem PartENat.dom_one :

instance PartENat.instCanLiftNatCastDom :

CanLift PartENat ℕ Nat.cast Part.Dom

instance PartENat.instLE :

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instance PartENat.instTop :

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instance PartENat.instBot :

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instance PartENat.instMax :

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theorem PartENat.le_def (x y : PartENat) :

x ≤ y ↔ ∃ (h : y.Dom → x.Dom), ∀ (hy : y.Dom), x.get ⋯ ≤ y.get hy

theorem PartENat.casesOn' {P : PartENat → Prop} (a : PartENat) :

P ⊤ → (∀ (n : ℕ), P ↑n) → P a

theorem PartENat.casesOn {P : PartENat → Prop} (a : PartENat) :

P ⊤ → (∀ (n : ℕ), P ↑n) → P a

theorem PartENat.top_add (x : PartENat) :

theorem PartENat.add_top (x : PartENat) :

@[simp]

theorem PartENat.natCast_get {x : PartENat} (h : x.Dom) :

↑(x.get h) = x

@[simp]

theorem PartENat.get_natCast' (x : ℕ) (h : (↑x).Dom) :

(↑x).get h = x

theorem PartENat.get_natCast {x : ℕ} :

(↑x).get ⋯ = x

theorem PartENat.coe_add_get {x : ℕ} {y : PartENat} (h : (↑x + y).Dom) :

(↑x + y).get h = x + y.get ⋯

@[simp]

theorem PartENat.get_add {x y : PartENat} (h : (x + y).Dom) :

(x + y).get h = x.get ⋯ + y.get ⋯

@[simp]

theorem PartENat.get_zero (h : Part.Dom 0) :

Part.get 0 h = 0

@[simp]

theorem PartENat.get_one (h : Part.Dom 1) :

Part.get 1 h = 1

@[simp]

theorem PartENat.get_ofNat' (x : ℕ) [x.AtLeastTwo] (h : (OfNat.ofNat x).Dom) :

(OfNat.ofNat x).get h = OfNat.ofNat x

theorem PartENat.get_eq_iff_eq_some {a : PartENat} {ha : a.Dom} {b : ℕ} :

a.get ha = b ↔ a = ↑b

theorem PartENat.get_eq_iff_eq_coe {a : PartENat} {ha : a.Dom} {b : ℕ} :

a.get ha = b ↔ a = ↑b

theorem PartENat.dom_of_le_of_dom {x y : PartENat} :

x ≤ y → y.Dom → x.Dom

theorem PartENat.dom_of_le_some {x : PartENat} {y : ℕ} (h : x ≤ ↑y) :

theorem PartENat.dom_of_le_natCast {x : PartENat} {y : ℕ} (h : x ≤ ↑y) :

instance PartENat.decidableLe (x y : PartENat) [Decidable x.Dom] [Decidable y.Dom] :

Decidable (x ≤ y)

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instance PartENat.partialOrder :

PartialOrder PartENat

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theorem PartENat.lt_def (x y : PartENat) :

x < y ↔ ∃ (hx : x.Dom), ∀ (hy : y.Dom), x.get hx < y.get hy

instance PartENat.isOrderedAddMonoid :

IsOrderedAddMonoid PartENat

instance PartENat.semilatticeSup :

SemilatticeSup PartENat

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instance PartENat.orderBot :

OrderBot PartENat

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instance PartENat.orderTop :

OrderTop PartENat

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instance PartENat.instZeroLEOneClass :

ZeroLEOneClass PartENat

theorem PartENat.coe_le_coe {x y : ℕ} :

↑x ≤ ↑y ↔ x ≤ y

Alias of Nat.cast_le specialized to PartENat

theorem PartENat.coe_lt_coe {x y : ℕ} :

↑x < ↑y ↔ x < y

Alias of Nat.cast_lt specialized to PartENat

@[simp]

theorem PartENat.get_le_get {x y : PartENat} {hx : x.Dom} {hy : y.Dom} :

x.get hx ≤ y.get hy ↔ x ≤ y

theorem PartENat.le_coe_iff (x : PartENat) (n : ℕ) :

x ≤ ↑n ↔ ∃ (h : x.Dom), x.get h ≤ n

theorem PartENat.lt_coe_iff (x : PartENat) (n : ℕ) :

x < ↑n ↔ ∃ (h : x.Dom), x.get h < n

theorem PartENat.coe_le_iff (n : ℕ) (x : PartENat) :

↑n ≤ x ↔ ∀ (h : x.Dom), n ≤ x.get h

theorem PartENat.coe_lt_iff (n : ℕ) (x : PartENat) :

↑n < x ↔ ∀ (h : x.Dom), n < x.get h

theorem PartENat.eq_zero_iff {x : PartENat} :

x = 0 ↔ x ≤ 0

theorem PartENat.ne_zero_iff {x : PartENat} :

x ≠ 0 ↔ ⊥ < x

theorem PartENat.dom_of_lt {x y : PartENat} :

x < y → x.Dom

theorem PartENat.top_eq_none :

⊤ = Part.none

@[simp]

theorem PartENat.natCast_lt_top (x : ℕ) :

↑x < ⊤

@[simp]

theorem PartENat.zero_lt_top :

@[simp]

theorem PartENat.one_lt_top :

@[simp]

theorem PartENat.ofNat_lt_top (x : ℕ) [x.AtLeastTwo] :

OfNat.ofNat x < ⊤

@[simp]

theorem PartENat.natCast_ne_top (x : ℕ) :

↑x ≠ ⊤

@[simp]

theorem PartENat.zero_ne_top :

@[simp]

theorem PartENat.one_ne_top :

@[simp]

theorem PartENat.ofNat_ne_top (x : ℕ) [x.AtLeastTwo] :

OfNat.ofNat x ≠ ⊤

theorem PartENat.not_isMax_natCast (x : ℕ) :

theorem PartENat.ne_top_iff {x : PartENat} :

x ≠ ⊤ ↔ ∃ (n : ℕ), x = ↑n

theorem PartENat.ne_top_iff_dom {x : PartENat} :

x ≠ ⊤ ↔ x.Dom

theorem PartENat.not_dom_iff_eq_top {x : PartENat} :

¬x.Dom ↔ x = ⊤

theorem PartENat.ne_top_of_lt {x y : PartENat} (h : x < y) :

theorem PartENat.eq_top_iff_forall_lt (x : PartENat) :

x = ⊤ ↔ ∀ (n : ℕ), ↑n < x

theorem PartENat.eq_top_iff_forall_le (x : PartENat) :

x = ⊤ ↔ ∀ (n : ℕ), ↑n ≤ x

theorem PartENat.pos_iff_one_le {x : PartENat} :

0 < x ↔ 1 ≤ x

instance PartENat.isTotal :

IsTotal PartENat fun (x1 x2 : PartENat) => x1 ≤ x2

noncomputable instance PartENat.linearOrder :

LinearOrder PartENat

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instance PartENat.boundedOrder :

BoundedOrder PartENat

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noncomputable instance PartENat.lattice :

Lattice PartENat

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instance PartENat.instCanonicallyOrderedAdd :

CanonicallyOrderedAdd PartENat

theorem PartENat.eq_natCast_sub_of_add_eq_natCast {x y : PartENat} {n : ℕ} (h : x + y = ↑n) :

x = ↑(n - y.get ⋯)

theorem PartENat.add_lt_add_right {x y z : PartENat} (h : x < y) (hz : z ≠ ⊤) :

x + z < y + z

theorem PartENat.add_lt_add_iff_right {x y z : PartENat} (hz : z ≠ ⊤) :

x + z < y + z ↔ x < y

theorem PartENat.add_lt_add_iff_left {x y z : PartENat} (hz : z ≠ ⊤) :

z + x < z + y ↔ x < y

theorem PartENat.lt_add_iff_pos_right {x y : PartENat} (hx : x ≠ ⊤) :

x < x + y ↔ 0 < y

theorem PartENat.lt_add_one {x : PartENat} (hx : x ≠ ⊤) :

x < x + 1

theorem PartENat.le_of_lt_add_one {x y : PartENat} (h : x < y + 1) :

x ≤ y

theorem PartENat.add_one_le_of_lt {x y : PartENat} (h : x < y) :

x + 1 ≤ y

theorem PartENat.add_one_le_iff_lt {x y : PartENat} (hx : x ≠ ⊤) :

x + 1 ≤ y ↔ x < y

theorem PartENat.coe_succ_le_iff {n : ℕ} {e : PartENat} :

↑n.succ ≤ e ↔ ↑n < e

theorem PartENat.lt_add_one_iff_lt {x y : PartENat} (hx : x ≠ ⊤) :

x < y + 1 ↔ x ≤ y

theorem PartENat.lt_coe_succ_iff_le {x : PartENat} {n : ℕ} (hx : x ≠ ⊤) :

x < ↑n.succ ↔ x ≤ ↑n

theorem PartENat.add_eq_top_iff {a b : PartENat} :

a + b = ⊤ ↔ a = ⊤ ∨ b = ⊤

theorem PartENat.add_right_cancel_iff {a b c : PartENat} (hc : c ≠ ⊤) :

a + c = b + c ↔ a = b

theorem PartENat.add_left_cancel_iff {a b c : PartENat} (ha : a ≠ ⊤) :

a + b = a + c ↔ b = c

def PartENat.toWithTop (x : PartENat) [Decidable x.Dom] :

Computably converts a PartENat to a ℕ∞.

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Instances For

theorem PartENat.toWithTop_top :

have this := Part.noneDecidable; ⊤.toWithTop = ⊤

@[simp]

theorem PartENat.toWithTop_top' {h : Decidable ⊤.Dom} :

⊤.toWithTop = ⊤

theorem PartENat.toWithTop_zero :

have this := Part.someDecidable 0; toWithTop 0 = 0

@[simp]

theorem PartENat.toWithTop_zero' {h : Decidable (Part.Dom 0)} :

toWithTop 0 = 0

theorem PartENat.toWithTop_one :

have this := Part.someDecidable 1; toWithTop 1 = 1

@[simp]

theorem PartENat.toWithTop_one' {h : Decidable (Part.Dom 1)} :

toWithTop 1 = 1

theorem PartENat.toWithTop_some (n : ℕ) :

(↑n).toWithTop = ↑n

theorem PartENat.toWithTop_natCast (n : ℕ) {x✝ : Decidable (↑n).Dom} :

(↑n).toWithTop = ↑n

@[simp]

theorem PartENat.toWithTop_natCast' (n : ℕ) {x✝ : Decidable (↑n).Dom} :

(↑n).toWithTop = ↑n

@[simp]

theorem PartENat.toWithTop_ofNat (n : ℕ) [n.AtLeastTwo] {x✝ : Decidable (Part.Dom (OfNat.ofNat n))} :

(OfNat.ofNat n).toWithTop = OfNat.ofNat n

@[simp]

theorem PartENat.toWithTop_le {x y : PartENat} [hx : Decidable x.Dom] [hy : Decidable y.Dom] :

x.toWithTop ≤ y.toWithTop ↔ x ≤ y

@[simp]

theorem PartENat.toWithTop_lt {x y : PartENat} [Decidable x.Dom] [Decidable y.Dom] :

x.toWithTop < y.toWithTop ↔ x < y

def PartENat.ofENat :

ℕ∞ → PartENat

Coercion from ℕ∞ to PartENat.

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Instances For

instance PartENat.instCoeENat :

Coe ℕ∞ PartENat

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@[simp]

theorem PartENat.ofENat_top :

@[simp]

theorem PartENat.ofENat_coe (n : ℕ) :

↑↑n = ↑n

@[simp]

theorem PartENat.ofENat_zero :

↑0 = 0

@[simp]

theorem PartENat.ofENat_one :

↑1 = 1

@[simp]

theorem PartENat.ofENat_ofNat (n : ℕ) [n.AtLeastTwo] :

↑(OfNat.ofNat n) = OfNat.ofNat n

@[simp]

theorem PartENat.toWithTop_ofENat (n : ℕ∞) {x✝ : Decidable (↑n).Dom} :

(↑n).toWithTop = n

@[simp]

theorem PartENat.ofENat_toWithTop (x : PartENat) {x✝ : Decidable x.Dom} :

↑x.toWithTop = x

@[simp]

theorem PartENat.ofENat_le {x y : ℕ∞} :

↑x ≤ ↑y ↔ x ≤ y

@[simp]

theorem PartENat.ofENat_lt {x y : ℕ∞} :

↑x < ↑y ↔ x < y

@[simp]

theorem PartENat.toWithTop_add {x y : PartENat} :

(x + y).toWithTop = x.toWithTop + y.toWithTop

noncomputable def PartENat.withTopEquiv :

PartENat ≃ ℕ∞

Equiv between PartENat and ℕ∞ (for the order isomorphism see withTopOrderIso).

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Instances For

@[simp]

theorem PartENat.withTopEquiv_symm_apply (x : ℕ∞) :

withTopEquiv.symm x = ↑x

@[simp]

theorem PartENat.withTopEquiv_apply (x : PartENat) :

withTopEquiv x = x.toWithTop

theorem PartENat.withTopEquiv_top :

withTopEquiv ⊤ = ⊤

theorem PartENat.withTopEquiv_natCast (n : ℕ) :

withTopEquiv ↑n = ↑n

theorem PartENat.withTopEquiv_zero :

withTopEquiv 0 = 0

theorem PartENat.withTopEquiv_one :

withTopEquiv 1 = 1

theorem PartENat.withTopEquiv_ofNat (n : ℕ) [n.AtLeastTwo] :

withTopEquiv (OfNat.ofNat n) = OfNat.ofNat n

theorem PartENat.withTopEquiv_le {x y : PartENat} :

withTopEquiv x ≤ withTopEquiv y ↔ x ≤ y

theorem PartENat.withTopEquiv_lt {x y : PartENat} :

withTopEquiv x < withTopEquiv y ↔ x < y

theorem PartENat.withTopEquiv_symm_top :

withTopEquiv.symm ⊤ = ⊤

theorem PartENat.withTopEquiv_symm_coe (n : ℕ) :

withTopEquiv.symm ↑n = ↑n

theorem PartENat.withTopEquiv_symm_zero :

withTopEquiv.symm 0 = 0

theorem PartENat.withTopEquiv_symm_one :

withTopEquiv.symm 1 = 1

theorem PartENat.withTopEquiv_symm_ofNat (n : ℕ) [n.AtLeastTwo] :

withTopEquiv.symm (OfNat.ofNat n) = OfNat.ofNat n

theorem PartENat.withTopEquiv_symm_le {x y : ℕ∞} :

withTopEquiv.symm x ≤ withTopEquiv.symm y ↔ x ≤ y

theorem PartENat.withTopEquiv_symm_lt {x y : ℕ∞} :

withTopEquiv.symm x < withTopEquiv.symm y ↔ x < y

noncomputable def PartENat.withTopOrderIso :

PartENat ≃o ℕ∞

toWithTop induces an order isomorphism between PartENat and ℕ∞.

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Instances For

noncomputable def PartENat.withTopAddEquiv :

PartENat ≃+ ℕ∞

toWithTop induces an additive monoid isomorphism between PartENat and ℕ∞.

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Instances For

theorem PartENat.lt_wf :

WellFounded fun (x1 x2 : PartENat) => x1 < x2

instance PartENat.instWellFoundedLT :

WellFoundedLT PartENat

instance PartENat.wellFoundedRelation :

WellFoundedRelation PartENat

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def PartENat.find (P : ℕ → Prop) [DecidablePred P] :

The smallest PartENat satisfying a (decidable) predicate P : ℕ → Prop

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Instances For

@[simp]

theorem PartENat.find_get (P : ℕ → Prop) [DecidablePred P] (h : (find P).Dom) :

(find P).get h = Nat.find h

theorem PartENat.find_dom (P : ℕ → Prop) [DecidablePred P] (h : ∃ (n : ℕ), P n) :

theorem PartENat.lt_find (P : ℕ → Prop) [DecidablePred P] (n : ℕ) (h : ∀ m ≤ n, ¬P m) :

↑n < find P

theorem PartENat.lt_find_iff (P : ℕ → Prop) [DecidablePred P] (n : ℕ) :

↑n < find P ↔ ∀ m ≤ n, ¬P m

theorem PartENat.find_le (P : ℕ → Prop) [DecidablePred P] (n : ℕ) (h : P n) :

find P ≤ ↑n

theorem PartENat.find_eq_top_iff (P : ℕ → Prop) [DecidablePred P] :

find P = ⊤ ↔ ∀ (n : ℕ), ¬P n

noncomputable instance PartENat.instLinearOrderedAddCommMonoidWithTop :

LinearOrderedAddCommMonoidWithTop PartENat

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noncomputable instance PartENat.instCompleteLinearOrder :

CompleteLinearOrder PartENat

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