Module structural 

WL-inspired structural fingerprinting for entity graph partitioning.

Adapts the 1-dimensional Weisfeiler-Leman colour refinement algorithm to Haystack entities. Each entity gets a structural fingerprint based on its tag set and the tag sets of its k-hop neighbors.

Structs

StructuralIndex

Structural index: maps entities to WL fingerprints and partitions entities by fingerprint for fast structural queries.