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This is the one family among the five whose defining engineering trade-off is temporal rather than architectural: cost is shifted from query time to index time. Writing $C_{\text{index}}$ for the one-time cost of building the graph and its community summaries, and $c_{\text{marginal}}$ for the cost of answering a single query against the finished structure, the amortised cost of a query workload of size Q against one graph is $c_{\text{query}}(Q) = \frac{C_{\text{index}}}{Q} + c_{\text{marginal}}$. When Q is small — a corpus queried rarely, or one still being explored — $C_{\text{index}}$ dominates and the naive or hybrid architectures are cheaper by a wide margin, because they pay nothing until a query arrives. When Q is large against a stable…

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