SG::ThinningDecisionBase Node1 SG::ThinningDecisionBase + RemovedIdx - m_mask + ThinningDecisionBase() + resize() + thinned() + size() + thinnedSize() + thinAll() + keepAll() + thin() + keep() + thin() and 7 more... Node2 std::vector< size_t > + elements Node2->Node1 -m_indexMap