PART IV - THE UNTIDY SOLAR SYSTEM
Small & Artificial Worlds at the Limits of the Protocol

The major planetary systems gave Solarian a relatively orderly first test.

Mars, Jupiter, Saturn, Uranus and Neptune each provide a clear heliocentric home, and their synchronized calendars scale from R2 to R179 without requiring new human units.

The next cases are less cooperative.

Part IV applies three different tests of generality:

ASTEROIDS — can one grammar work across a population of independent natural worlds rather than a handful of carefully chosen examples?

FREE SPACE — what happens when humans build the world themselves and can partly choose its astronomical environment?

PLUTO — can the protocol recognise when its standard astronomical representation has stopped being good enough?

These are deliberately harder questions.

The asteroid belt replaces one tidy planetary system with thousands of independent orbits. Artificial habitats turn part of the astronomical problem into a design choice. Pluto then produces the most important challenge of all: arithmetic that still works while the representation it supports becomes misleading.

A useful general architecture should do more than succeed on favourable examples.

It should generalise where it can, adapt where the environment changes, and say no when its standard form has reached a real boundary.

This Part tests all three.