{"id":"height-zero-for-none","text":"The empty tree (`None`) is defined as having height 0 in balanced-binary-tree, making `max(left, right) + 1` produce height 1 for a single leaf node — a foundational invariant the recursion depends on.","truth_value":"IN","source":"entries/2026/06/06/balanced-binary-tree-solution.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"height-zero-for-none","truth_value":"IN","reason":"premise"}]}}