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Mathlib.Data.Finset.MulAntidiagonal

Multiplication antidiagonal as a Finset. #

We construct the Finset of all pairs of an element in s and an element in t that multiply to a, given that s and t are well-ordered.

theorem Set.IsPwo.add {α : Type u_1} {s : Set α} {t : Set α} [OrderedCancelAddCommMonoid α] (hs : Set.IsPwo s) (ht : Set.IsPwo t) :
Set.IsPwo (s + t)
theorem Set.IsPwo.mul {α : Type u_1} {s : Set α} {t : Set α} [OrderedCancelCommMonoid α] (hs : Set.IsPwo s) (ht : Set.IsPwo t) :
Set.IsPwo (s * t)
theorem Set.IsWf.add {α : Type u_1} {s : Set α} {t : Set α} [LinearOrderedCancelAddCommMonoid α] (hs : Set.IsWf s) (ht : Set.IsWf t) :
Set.IsWf (s + t)
theorem Set.IsWf.mul {α : Type u_1} {s : Set α} {t : Set α} [LinearOrderedCancelCommMonoid α] (hs : Set.IsWf s) (ht : Set.IsWf t) :
Set.IsWf (s * t)
theorem Set.IsWf.min_add {α : Type u_1} {s : Set α} {t : Set α} [LinearOrderedCancelAddCommMonoid α] (hs : Set.IsWf s) (ht : Set.IsWf t) (hsn : Set.Nonempty s) (htn : Set.Nonempty t) :
Set.IsWf.min (_ : Set.IsWf (s + t)) (_ : Set.Nonempty (s + t)) = Set.IsWf.min hs hsn + Set.IsWf.min ht htn
theorem Set.IsWf.min_mul {α : Type u_1} {s : Set α} {t : Set α} [LinearOrderedCancelCommMonoid α] (hs : Set.IsWf s) (ht : Set.IsWf t) (hsn : Set.Nonempty s) (htn : Set.Nonempty t) :
Set.IsWf.min (_ : Set.IsWf (s * t)) (_ : Set.Nonempty (s * t)) = Set.IsWf.min hs hsn * Set.IsWf.min ht htn
noncomputable def Finset.addAntidiagonal {α : Type u_1} [OrderedCancelAddCommMonoid α] {s : Set α} {t : Set α} (hs : Set.IsPwo s) (ht : Set.IsPwo t) (a : α) :
Finset (α × α)

Finset.addAntidiagonal hs ht a is the set of all pairs of an element in s and an element in t that add to a, but its construction requires proofs that s and t are well-ordered.

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    noncomputable def Finset.mulAntidiagonal {α : Type u_1} [OrderedCancelCommMonoid α] {s : Set α} {t : Set α} (hs : Set.IsPwo s) (ht : Set.IsPwo t) (a : α) :
    Finset (α × α)

    Finset.mulAntidiagonal hs ht a is the set of all pairs of an element in s and an element in t that multiply to a, but its construction requires proofs that s and t are well-ordered.

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      @[simp]
      theorem Finset.mem_addAntidiagonal {α : Type u_1} [OrderedCancelAddCommMonoid α] {s : Set α} {t : Set α} {hs : Set.IsPwo s} {ht : Set.IsPwo t} {a : α} {x : α × α} :
      x Finset.addAntidiagonal hs ht a x.fst s x.snd t x.fst + x.snd = a
      @[simp]
      theorem Finset.mem_mulAntidiagonal {α : Type u_1} [OrderedCancelCommMonoid α] {s : Set α} {t : Set α} {hs : Set.IsPwo s} {ht : Set.IsPwo t} {a : α} {x : α × α} :
      x Finset.mulAntidiagonal hs ht a x.fst s x.snd t x.fst * x.snd = a
      theorem Finset.addAntidiagonal_mono_left {α : Type u_1} [OrderedCancelAddCommMonoid α] {s : Set α} {t : Set α} {hs : Set.IsPwo s} {ht : Set.IsPwo t} {a : α} {u : Set α} {hu : Set.IsPwo u} (h : u s) :
      theorem Finset.mulAntidiagonal_mono_left {α : Type u_1} [OrderedCancelCommMonoid α] {s : Set α} {t : Set α} {hs : Set.IsPwo s} {ht : Set.IsPwo t} {a : α} {u : Set α} {hu : Set.IsPwo u} (h : u s) :
      theorem Finset.addAntidiagonal_mono_right {α : Type u_1} [OrderedCancelAddCommMonoid α] {s : Set α} {t : Set α} {hs : Set.IsPwo s} {ht : Set.IsPwo t} {a : α} {u : Set α} {hu : Set.IsPwo u} (h : u t) :
      theorem Finset.mulAntidiagonal_mono_right {α : Type u_1} [OrderedCancelCommMonoid α] {s : Set α} {t : Set α} {hs : Set.IsPwo s} {ht : Set.IsPwo t} {a : α} {u : Set α} {hu : Set.IsPwo u} (h : u t) :
      theorem Finset.swap_mem_addAntidiagonal {α : Type u_1} [OrderedCancelAddCommMonoid α] {s : Set α} {t : Set α} {hs : Set.IsPwo s} {ht : Set.IsPwo t} {a : α} {x : α × α} :
      theorem Finset.swap_mem_mulAntidiagonal {α : Type u_1} [OrderedCancelCommMonoid α] {s : Set α} {t : Set α} {hs : Set.IsPwo s} {ht : Set.IsPwo t} {a : α} {x : α × α} :
      abbrev Finset.support_addAntidiagonal_subset_add.match_1 {α : Type u_1} [OrderedCancelAddCommMonoid α] {s : Set α} {t : Set α} {hs : Set.IsPwo s} {ht : Set.IsPwo t} (a : α) (motive : a {a | Finset.Nonempty (Finset.addAntidiagonal hs ht a)}Prop) :
      (x : a {a | Finset.Nonempty (Finset.addAntidiagonal hs ht a)}) → ((b : α × α) → (hb : b Finset.addAntidiagonal hs ht a) → motive (_ : x, x Finset.addAntidiagonal hs ht a)) → motive x
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        theorem Finset.addAntidiagonal_min_add_min {α : Type u_2} [LinearOrderedCancelAddCommMonoid α] {s : Set α} {t : Set α} (hs : Set.IsWf s) (ht : Set.IsWf t) (hns : Set.Nonempty s) (hnt : Set.Nonempty t) :
        theorem Finset.mulAntidiagonal_min_mul_min {α : Type u_2} [LinearOrderedCancelCommMonoid α] {s : Set α} {t : Set α} (hs : Set.IsWf s) (ht : Set.IsWf t) (hns : Set.Nonempty s) (hnt : Set.Nonempty t) :