Rank Two det factor
ProvedD1Bound5.rankTwo_det_factordiophantine-tuplesnumber-theory
A four-by-four determinant under a rank-two update reduces exactly to a two-by-two determinant; no adjoints or Hermitian hypotheses.
Preamble
import Mathlib.Analysis.CStarAlgebra.Matrix import Mathlib.Analysis.Complex.Basic import Mathlib.Analysis.Complex.Polynomial.Basic import Mathlib.Analysis.InnerProductSpace.PiL2 import Mathlib.Analysis.SpecificLimits.Normed import Mathlib.Data.Complex.Basic import Mathlib.LinearAlgebra.Matrix.Determinant.Basic import Mathlib.LinearAlgebra.Matrix.NonsingularInverse import Mathlib.LinearAlgebra.Matrix.Permutation import Mathlib.LinearAlgebra.Matrix.SchurComplement import Mathlib.Tactic.FieldSimp import Mathlib.Tactic.FinCases import Mathlib.Tactic.Linarith import Mathlib.Tactic.LinearCombination import Mathlib.Tactic.NormNum import Mathlib.Tactic.Ring
Formal statement
section
open Matrix
namespace D1Bound5
theorem _root_.D1Bound5.rankTwo_det_factor
(F : Matrix (Fin 4) (Fin 4) ℂ)
(U : Matrix (Fin 4) (Fin 2) ℂ)
(V : Matrix (Fin 2) (Fin 4) ℂ)
(hF : F.det ≠ 0) :
(F + U * V).det =
F.det * ((1 : Matrix (Fin 2) (Fin 2) ℂ) + V * F⁻¹ * U).det := by sorry
end D1Bound5
end
Source
D1Bound5/ProductFiveRankTwo.lean, lines 7-28, SHA-256 0cec92c96e51a0a3fbd94ad6a62d3e917e83332e75de37d2fd74599e197b4902. Project: https://github.com/tomislav-math/d1-bound5-lean