What does this equation mean?

Both approaches share the same engineering consequence: the number of retrieval-generation rounds, call it k , is no longer fixed at one. Latency and cost scale with k , and unlike the naive or hybrid families, k is now a property of the question rather than of the architecture — a single-hop question still costs roughly one round, but a four-hop question costs roughly four, and the system pays that multiplier whether or not the caller anticipated it. IRCoT bounds this in practice by capping the number of reasoning steps and by using retrieval and reasoning specifically tuned for the multi-hop benchmarks it was evaluated on; FLARE bounds it by triggering additional retrieval only on measured low confidence rather than at every step, which keeps the multiplier close to one on easy inputs and lets it grow on hard ones. Neither of these figures — the reported point gains on multi-hop QA benchmarks — is comparable to GraphRAG’s comprehensiveness gains on corpus summarisation or to Self-RAG’s citation-accuracy figures discussed next; they were measured on different tasks built to expose different failures, and citing one as evidence against another would be a category error, not a finding.