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Golden Projective Derivative

Abstract

The golden Mobius derivative equals its projective multiplier.

Theorem 1.1 (Golden Mobius Has Deriv At).

Proof. Machine-checked in Lean as D5/S3/CompletionDynamics/GoldenMobius/GoldenProjectiveDerivative.golden_mobius_hasDerivAt (✓ std3). ∎

Source. Repository-derived.

Commentary.

Ordinary differentiation gives the same multiplier as exact projective linearization.

The declaration keeps its parameters and hypotheses explicit; the result makes no converse or broader existence claim beyond that scope.

Theorem 1.2 (Deriv Golden Mobius At Golden).

Proof. Machine-checked in Lean as D5/S3/CompletionDynamics/GoldenMobius/GoldenProjectiveDerivative.deriv_golden_mobius_at_golden (✓ std3). ∎

Source. Repository-derived.

Commentary.

Evaluation of deriv at the golden fixed point.

The declaration keeps its parameters and hypotheses explicit; the result makes no converse or broader existence claim beyond that scope.

Theorem 1.3 (Abs Golden Projective Multiplier).

Proof. Machine-checked in Lean as D5/S3/CompletionDynamics/GoldenMobius/GoldenProjectiveDerivative.abs_golden_projective_multiplier (✓ std3). ∎

Source. Repository-derived.

Commentary.

The projective multiplier has the expected positive magnitude.

The declaration keeps its parameters and hypotheses explicit; the result makes no converse or broader existence claim beyond that scope.

Theorem 1.4 (Abs Golden Projective Multiplier lt One).

Proof. Machine-checked in Lean as D5/S3/CompletionDynamics/GoldenMobius/GoldenProjectiveDerivative.abs_golden_projective_multiplier_lt_one (✓ std3). ∎

Source. Repository-derived.

Commentary.

The completion derivative is a strict contraction in projective coordinates.

The declaration keeps its parameters and hypotheses explicit; the result makes no converse or broader existence claim beyond that scope.

Theorem 1.5 (Linearized Golden Has Deriv At Zero).

Proof. Machine-checked in Lean as D5/S3/CompletionDynamics/GoldenMobius/GoldenProjectiveDerivative.linearized_golden_hasDerivAt_zero (✓ std3). ∎

Source. Repository-derived.

Commentary.

Multiplication by the golden multiplier has that derivative at zero.

The declaration keeps its parameters and hypotheses explicit; the result makes no converse or broader existence claim beyond that scope.

References

  • Truth anchor: D5/S3/CompletionDynamics/GoldenMobius/GoldenProjectiveDerivative.abs_golden_projective_multiplier
  • Truth anchor: D5/S3/CompletionDynamics/GoldenMobius/GoldenProjectiveDerivative.abs_golden_projective_multiplier_lt_one
  • Truth anchor: D5/S3/CompletionDynamics/GoldenMobius/GoldenProjectiveDerivative.deriv_golden_mobius_at_golden
  • Truth anchor: D5/S3/CompletionDynamics/GoldenMobius/GoldenProjectiveDerivative.golden_mobius_hasDerivAt
  • Truth anchor: D5/S3/CompletionDynamics/GoldenMobius/GoldenProjectiveDerivative.linearized_golden_hasDerivAt_zero
  • Dependency: D5/S3/CompletionDynamics/GoldenMobius/GoldenCrossRatioLinearization