Breadth-First, Run Whole

A complete breadth-first run on a small map shows competence assembling out of pure bookkeeping.

Riverbend, start Home, goal Grandmother's, neighbors filed alphabetically. Turn one: select Home; not the goal; file Home–Bakery and Home–School. Turn two: select Home–Bakery; file Home–Bakery–Park. Turn three: select Home–School; file its extensions to Clinic and Park. Turns four through six: the three-road paths come up for selection in the order they were filed — the Bakery line first, then the School lines — each failing the goal test, each filing its own extensions. Turn seven: select Home–Bakery–Park–Grandmother's. Goal. Three roads: Home, Bakery, Park, Grandmother's — and inspection of the map shows no two-road route exists.