Status: IN
Visitor's dual class hierarchy architecture (elements and visitors as orthogonal hierarchies) is the structural mechanism that makes stateful recursive operations possible: because visitors can compute across elements sharing no common parent, the recursive triad's traversal flexibility extends to heterogeneous structures — the dual hierarchy eliminates the structural constraint that would otherwise limit stateful accumulation to homogeneous collections.
Dual hierarchy architecture directly enables heterogeneous stateful recursive computation
Depends on (SL): visitor-dual-hierarchy-enables-structural-independence, visitor-recursive-stateful-operations