LeanMachineLearning exposition

argmax_spec🔗

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Minimal Lean file

argmax_spec🔗

Lemmaargmax_spec
Details

No docstring.

🔗theorem
argmax_spec.{u_1, u_2} {ι : Type u_1} {α : Type u_2} [LinearOrder α]
  [Fintype ι] [Nonempty ι] (f : ι → α) : f (argmax f) = Function.max f
argmax_spec.{u_1, u_2} {ι : Type u_1}
  {α : Type u_2} [LinearOrder α]
  [Fintype ι] [Nonempty ι] (f : ι → α) :
  f (argmax f) = Function.max f

Code

lemma argmax_spec : f (argmax f) = f.max
Type uses (2)
Body uses (1)
Used by (1)

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Proof
(exists_argmax f).choose_spec

Dependency graph

Type dependencies (2)

argmax🔗

Definitionargmax
Details

The index of the maximum value of a tuple.

🔗def
argmax.{u_1, u_2} {ι : Type u_1} {α : Type u_2} [LinearOrder α]
  [Fintype ι] [Nonempty ι] (f : ι → α) : ι
argmax.{u_1, u_2} {ι : Type u_1}
  {α : Type u_2} [LinearOrder α]
  [Fintype ι] [Nonempty ι] (f : ι → α) : ι

Code

noncomputable def argmax := (exists_argmax f).choose
Body uses (2)
Used by (17)

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max🔗

DefinitionFunction.max
Details

The maximum value of a tuple.

🔗def
Function.max.{u_1, u_2} {ι : Type u_1} {α : Type u_2} [LinearOrder α]
  [Fintype ι] [Nonempty ι] (f : ι → α) : α
Function.max.{u_1, u_2} {ι : Type u_1}
  {α : Type u_2} [LinearOrder α]
  [Fintype ι] [Nonempty ι] (f : ι → α) : α

Code

abbrev max : α := univ.sup' univ_nonempty f
Used by (8)

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All dependencies, transitively (1)

exists_argmax🔗

Lemmaexists_argmax
Details

No docstring.

🔗theorem
exists_argmax.{u_1, u_2} {ι : Type u_1} {α : Type u_2} [LinearOrder α]
  [Fintype ι] [Nonempty ι] (f : ι → α) : ∃ i, f i = Function.max f
exists_argmax.{u_1, u_2} {ι : Type u_1}
  {α : Type u_2} [LinearOrder α]
  [Fintype ι] [Nonempty ι] (f : ι → α) :
  ∃ i, f i = Function.max f

Code

lemma exists_argmax : ∃ i, f i = f.max
Type uses (1)
Used by (3)

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Proof
by
  obtain ⟨i, -, hi⟩ := Finset.exists_mem_eq_sup' (by simp : Finset.univ.Nonempty) f
  exact ⟨i, hi.symm⟩