Explanation of defectDist
(1) In plain English, defectDist defines a function that takes two real numbers x and y and returns the J-cost of their ratio x/y. This measures the "cost of deviation" between x and y under the J-cost function.
(2) In Recognition Science it supplies the defect pseudometric on positive reals. The pseudometric is the algebraic object that lets the Recognition Composition Law induce a notion of distance, which is then used to derive quasi-triangle bounds and to connect cost composition to the shifted monoid structure.
(3) The formal statement is the noncomputable definition
noncomputable def defectDist (x y : ℝ) : ℝ := J (x / y)
J is the J-cost J imported from the Cost module; the definition simply applies it to the ratio.
(4) Visible dependencies and certificates in the supplied source are the three immediate properties defectDist_self, defectDist_symm and defectDist_nonneg, each proved from J_at_one, J_reciprocal and J_nonneg. The local quasi-triangle bound appears as defectDist_quasi_triangle_local and the auxiliary bound J_le_J_of_inv_le_le.
(5) The declaration itself does not prove a global triangle inequality, does not establish that defectDist is a true metric, and does not derive any physical constants or spacetime structure; those steps lie in other modules.