Adding slab coordinates to a flag fibre #
The completeness refinement augments a fibre by finitely many affine functionals. These coordinate maps project to the old fibre, retain the additional coordinates along lower transitions, and commute with scalar extension and reduction modulo every modulus.
Linear projection onto the first block of coordinates.
Equations
- EGZ.Coord.first m k = LinearMap.pi fun (i : Fin m) => LinearMap.proj (Fin.castAdd k i)
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Linear projection onto the last block of coordinates.
Equations
- EGZ.Coord.last m k = LinearMap.pi fun (i : Fin k) => LinearMap.proj (Fin.natAdd m i)
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Append the outputs of two affine maps in the standard finite coordinates.
Equations
- EGZ.Coord.append A B = AffineMap.pi fun (i : Fin (m + k)) => Fin.addCases (fun (i : Fin m) => (AffineMap.proj i).comp A) (fun (i : Fin k) => (AffineMap.proj i).comp B) i
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Extend an affine map while leaving additional coordinates fixed.
Equations
- EGZ.Coord.extend A k = EGZ.Coord.append (A.comp (EGZ.Coord.first m k).toAffineMap) (EGZ.Coord.last m k).toAffineMap
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Forget the extra coordinates of an augmented lattice fibre.
Equations
- One or more equations did not get rendered due to their size.
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Apply an old transition and keep the newly added slab coordinates.
Equations
- A.extend k = { real := EGZ.Coord.extend A.real k, integer := ⇑(EGZ.Coord.extend A.toIntAffineMap k), modp := fun (p : ℕ) => EGZ.Coord.extend (A.modp p) k, real_integer := ⋯, mod_integer := ⋯ }
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Keep the initial coordinates of a finite coordinate vector.
Equations
- EGZ.Coord.prefixMap es et h = LinearMap.pi fun (i : Fin et) => LinearMap.proj (Fin.castLE h i)
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Apply an affine map to the old coordinates and keep an initial segment of the additional coordinates.
Equations
- EGZ.Coord.extendPrefix A es et h = EGZ.Coord.append (A.comp (EGZ.Coord.first m es).toAffineMap) ((EGZ.Coord.prefixMap es et h).toAffineMap.comp (EGZ.Coord.last m es).toAffineMap)
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Extend an integral-affine map while retaining an initial segment of its additional coordinates.
Equations
- One or more equations did not get rendered due to their size.