propagation-is-bfs

IN premise — entries/2026/04/23/reasons_lib-network.md

Truth value propagation in `_propagate` uses `deque`-based BFS through the `dependents` graph, not DFS, ensuring breadth-first wavefront expansion.

Summary

The propagation algorithm spreads truth value changes level by level outward from the source, visiting all immediate dependents before moving deeper. This matters because breadth-first ordering guarantees that nodes closer to the change are updated before distant ones, avoiding scenarios where a deep node gets an intermediate or inconsistent value that would need to be re-corrected later.

Dependents

These beliefs depend on this one:

IN propagation-is-crash-free — Truth propagation completes without runtime errors across all reachable nodes
IN propagation-terminates-deterministically — Truth propagation is guaranteed to terminate: BFS prevents stack overflow, stop-on-unchanged prevents oscillation, and fixpoint iteration bounds the outer loop