{"id":"tree2str-empty-left-parens-preserved","text":"`tree2str` emits `()` for a missing left child if and only if the right child exists, preserving positional unambiguity in the serialized output.","truth_value":"IN","source":"entries/2026/06/06/construct-string-from-binary-tree-solution.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"tree2str-empty-left-parens-preserved","truth_value":"IN","reason":"premise"}]}}