Family hydrodynamic

The contract in words, and how to choose

No hand-written part: how to choose among this family’s laws, or to attach them together, is not written yet.

Contract

What every member must satisfy, as the family’s harness checks it on the member’s own node.

• Sign rule: the resistance dissipates: V^T R V > 0 for every nonzero twist, R symmetric positive definite

• Cases a member passes: sign, frame, units, material reach, oracle, gradients, swap, nodes

• Settings that stand for a material’s properties, each of which must reach the output: viscosity

• Deliveries a two-way law makes equal and opposite: none

• Reference member a swap replaces: none

• Settings proportional to a material property: viscosity

Members

Entry	Rung	Derivative
drag 0.4.0	surrogate	piecewise_jump
drag 0.4.0	mrs	exact

Comparison

Member	Validity	Checked against	Cost	Derivative	Needs a GPU
drag surrogate	9 declared lines, free text, not parsed	not measured	not measured	piecewise_jump	not measured
drag mrs	9 declared lines, free text, not parsed	not measured	not measured	exact	not measured

A cell reads not measured until a measurement record or a claim holds it, and each is counted.