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Negative Direction in a Full Evaluation Image

Abstract

A full two-coordinate complex evaluation image contains a strictly negative cross direction.

Theorem 1.1 (A full two-coordinate evaluation has a negative cross direction).

Proof. Machine-checked in Lean as D5/S3/Weil/ZetaBridge/TwoDimensionalEvaluationNegativeDirection.two_dimensional_evaluation_has_negative_direction (✓ std3). ∎

Source. Repository-derived.

Commentary.

Let T be a complex vector space and E a complex-linear map from T to two complex coordinates. If the image of E has complex dimension two, then it is the entire coordinate space. For every positive natural multiplicity m, the theorem produces g in T for which four times m times the real part of the first coordinate multiplied by the conjugate of the second is strictly negative.

Mathlib’s maximal-finrank submodule theorem turns the rank hypothesis into surjectivity. Lift the coordinate pair (1,-1) through E; its cross value is -4m, which is negative because m is positive. The identity evaluation on the two-coordinate complex space witnesses that the hypotheses are jointly satisfiable.

The cross value is the same multiplicity-weighted real cross term used by the neighboring convolution-square orbit formulas.

References