11.9 Design lesson

BRIDGE/SKFM demonstrates a general LINCS pattern: an obstruction need not directly name the missing structure to be useful. A calibrated, nonspecific geometric diagnostic can still reduce a combinatorial search dramatically, provided its retention guarantee, falsification battery, downstream estimand, and abstention boundary remain visible.

This application also displays the two modeling levels introduced in the foundations. The SCM or causal graph is a model of the biological or experimental domain; the BRIDGE/SKFM sketch is a model of the discovery system that estimates fields, screens relations, invokes a downstream learner, and admits or rejects the resulting structure. LINCS makes the second system actionable without pretending that changes to its screen are interventions on the biological system. Domain surgery and learning-system repair can interact, but their semantics and evidence remain distinct.