Samplinglib
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AutoSamplingTheory.TechnicalLemmas.Measure.DisplacementDerivativeDetPos

6 named declarations scanned from AutoSamplingTheory/TechnicalLemmas/Measure/DisplacementDerivativeDetPos.lean.

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theorem AutoSamplingTheory.TechnicalLemmas.Measure.DisplacementDerivativeDetPos.toMatrix_affineDisplacementDerivative_posDef Partial Not mapped

- An SPD matrix representation of the endpoint derivative gives an SPD matrix representation of the affine displacement derivative on the full segment.

theorem toMatrix_affineDisplacementDerivative_posDef
    (b : Module.Basis ι ℝ E) (T' : E →L[ℝ] E)
    (hT : (LinearMap.toMatrix b b T'.toLinearMap).PosDef)
    (t : ℝ) (ht0 : 0 ≤ t) (ht1 : t ≤ 1) :
    (LinearMap.toMatrix b b
      (affineDisplacementDerivative T' t).toLinearMap).PosDef := by
  rw [toMatrix_affineDisplacementDerivative]
  exact affineIdentityMatrix_posDef
    (LinearMap.toMatrix b b T'.toLinearMap) hT t ht0 ht1

/-- A PSD endpoint derivative is already enough for strict positivity of the
interior affine derivative matrix. -/
theorem AutoSamplingTheory.TechnicalLemmas.Measure.DisplacementDerivativeDetPos.toMatrix_affineDisplacementDerivative_posDef_of_posSemidef Partial Not mapped

- A PSD endpoint derivative is already enough for strict positivity of the interior affine derivative matrix.

theorem toMatrix_affineDisplacementDerivative_posDef_of_posSemidef
    (b : Module.Basis ι ℝ E) (T' : E →L[ℝ] E)
    (hT : (LinearMap.toMatrix b b T'.toLinearMap).PosSemidef)
    (t : ℝ) (ht0 : 0 ≤ t) (ht1 : t < 1) :
    (LinearMap.toMatrix b b
      (affineDisplacementDerivative T' t).toLinearMap).PosDef := by
  rw [toMatrix_affineDisplacementDerivative]
  exact affineIdentityMatrix_posDef_of_posSemidef
    (LinearMap.toMatrix b b T'.toLinearMap) hT t ht0 ht1

/-- Under an SPD endpoint derivative, the continuous-linear determinant of the
affine displacement derivative is strictly positive. -/
theorem AutoSamplingTheory.TechnicalLemmas.Measure.DisplacementDerivativeDetPos.det_affineDisplacementDerivative_pos Partial Not mapped

- Under an SPD endpoint derivative, the continuous-linear determinant of the affine displacement derivative is strictly positive.

theorem det_affineDisplacementDerivative_pos
    (b : Module.Basis ι ℝ E) (T' : E →L[ℝ] E)
    (hT : (LinearMap.toMatrix b b T'.toLinearMap).PosDef)
    (t : ℝ) (ht0 : 0 ≤ t) (ht1 : t ≤ 1) :
    0 < LinearMap.det (affineDisplacementDerivative T' t).toLinearMap := by
  rw [det_affineDisplacementDerivative_eq_matrix_det b T' t]
  exact (affineIdentityMatrix_posDef
    (LinearMap.toMatrix b b T'.toLinearMap) hT t ht0 ht1).det_pos

/-- Interior-time determinant positivity from the weaker PSD endpoint
hypothesis. -/
theorem AutoSamplingTheory.TechnicalLemmas.Measure.DisplacementDerivativeDetPos.det_affineDisplacementDerivative_pos_of_posSemidef Partial Not mapped

- Interior-time determinant positivity from the weaker PSD endpoint hypothesis.

theorem det_affineDisplacementDerivative_pos_of_posSemidef
    (b : Module.Basis ι ℝ E) (T' : E →L[ℝ] E)
    (hT : (LinearMap.toMatrix b b T'.toLinearMap).PosSemidef)
    (t : ℝ) (ht0 : 0 ≤ t) (ht1 : t < 1) :
    0 < LinearMap.det (affineDisplacementDerivative T' t).toLinearMap := by
  rw [det_affineDisplacementDerivative_eq_matrix_det b T' t]
  exact (affineIdentityMatrix_posDef_of_posSemidef
    (LinearMap.toMatrix b b T'.toLinearMap) hT t ht0 ht1).det_pos

/-- The absolute determinant in change of variables is redundant under an SPD
endpoint derivative. -/
theorem AutoSamplingTheory.TechnicalLemmas.Measure.DisplacementDerivativeDetPos.abs_det_affineDisplacementDerivative_eq Partial Not mapped

- The absolute determinant in change of variables is redundant under an SPD endpoint derivative.

theorem abs_det_affineDisplacementDerivative_eq
    (b : Module.Basis ι ℝ E) (T' : E →L[ℝ] E)
    (hT : (LinearMap.toMatrix b b T'.toLinearMap).PosDef)
    (t : ℝ) (ht0 : 0 ≤ t) (ht1 : t ≤ 1) :
    |LinearMap.det (affineDisplacementDerivative T' t).toLinearMap| =
      LinearMap.det (affineDisplacementDerivative T' t).toLinearMap :=
  abs_of_pos (det_affineDisplacementDerivative_pos b T' hT t ht0 ht1)

/-- Interior-time absolute-determinant removal from a PSD endpoint derivative. -/
theorem AutoSamplingTheory.TechnicalLemmas.Measure.DisplacementDerivativeDetPos.abs_det_affineDisplacementDerivative_eq_of_posSemidef Partial Not mapped

- Interior-time absolute-determinant removal from a PSD endpoint derivative.

theorem abs_det_affineDisplacementDerivative_eq_of_posSemidef
    (b : Module.Basis ι ℝ E) (T' : E →L[ℝ] E)
    (hT : (LinearMap.toMatrix b b T'.toLinearMap).PosSemidef)
    (t : ℝ) (ht0 : 0 ≤ t) (ht1 : t < 1) :
    |LinearMap.det (affineDisplacementDerivative T' t).toLinearMap| =
      LinearMap.det (affineDisplacementDerivative T' t).toLinearMap :=
  abs_of_pos
    (det_affineDisplacementDerivative_pos_of_posSemidef b T' hT t ht0 ht1)

end

end DisplacementDerivativeDetPos
end Measure
end TechnicalLemmas
end AutoSamplingTheory