Documentation

HexPermGroupTheory.WreathProduct

def Hex.PermGroup.WreathProduct.shift {n m : ℕ} (G : Group n) (H : Group m) :

The top group acts on the base functions by inverse reindexing.

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    def Hex.PermGroup.WreathProduct.equiv {n m : ℕ} (G : Group n) (H : Group m) (hn : 0 < n) :

    The imprimitive permutation group is the semidirect product G^m ⋊ H, with the executable base and top projections as the equivalence.

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      @[simp]
      theorem Hex.PermGroup.WreathProduct.equiv_pair {n m : ℕ} (G : Group n) (H : Group m) (hn : 0 < n) (f : Fin m → Element G) (h : Element H) :
      (equiv G H hn) (pair f h) = ⟨f, h⟩
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          The executable top projection. With empty blocks it is the trivial map.

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            theorem Hex.PermGroup.WreathProduct.range_inl {n m : ℕ} (G : Group n) (H : Group m) :
            (inlHom G H).range = (topHom G H).ker
            theorem Hex.PermGroup.WreathProduct.equiv_inl {n m : ℕ} (G : Group n) (H : Group m) (hn : 0 < n) (f : Fin m → Element G) :
            (equiv G H hn) (inl H f) = SemidirectProduct.inl f
            theorem Hex.PermGroup.WreathProduct.equiv_inr {n m : ℕ} (G : Group n) (H : Group m) (hn : 0 < n) (h : Element H) :
            (equiv G H hn) (inr G h) = SemidirectProduct.inr h

            Inverse reindexing stated entirely in the generated Mathlib subgroups.

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              The checked permutation subgroup is multiplicatively equivalent to the Mathlib semidirect product of its mathematical factors.

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                theorem Hex.PermGroup.WreathProduct.groupEquiv_pair {n m : ℕ} (G : Group n) (H : Group m) (hn : 0 < n) (f : Fin m → Element G) (h : Element H) :
                (groupEquiv G H hn) ((Element.equiv (G.wreathProduct H)) (pair f h)) = ⟨fun (j : Fin m) => (Element.equiv G) (f j), (Element.equiv H) h⟩