A Symmetric Layer-Union Audit of Component Collapse in Hierarchical Procedural Corpora

Abstract

Component-disjoint leakage control can group corpus units by content similarity, hierarchical membership, or both. Guvenilir and Dogan previously showed that merging relation types can create a giant component that obstructs splitting; we do not claim this phenomenon as new. We examine it through a symmetric audit of a content-near-duplicate layer, a common-container layer, and their union in a fixed panel of six hierarchical procedural corpora. MyFixit and Doc2Dial exhibit the individual-layer-pass/union-fail pattern under the same operational criteria. The resulting two-of-six fraction describes this deliberately constructed panel and is not a prevalence estimate. A prespecified bridge-specific predictor is associated with the pattern, but it is not distinguished from a registered union-density control; the panel therefore does not identify a bridge-specific mechanism. Secondary diagnostics bound the interpretation of threshold sensitivity, annotation coverage, and lexical cues without extending those findings beyond their recorded sources and definitions. The paper's contribution is a bounded measurement and audit: it keeps relation families visible, evaluates their individual and union component structures symmetrically, and reports negative cases and mechanism limits. It proposes neither a new splitting algorithm nor a general causal claim about relation unions.