{"id":"valid-parentheses-final-stack-empty-check","text":"The final `return not stack` is required to reject inputs with unmatched openers (e.g., `\"(\"`); without it, any string whose closers all match would pass regardless of leftover openers.","truth_value":"IN","source":"entries/2026/06/06/valid-parentheses-solution.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"valid-parentheses-final-stack-empty-check","truth_value":"IN","reason":"premise"}]}}