import type { SearchResult } from "../types.js";
/**
 * Reciprocal Rank Fusion (RRF) combining BM25 + semantic search results.
 *
 * Formula: score(d) = Σ 1/(k + rank_i(d))
 * where k=60 is the standard RRF constant and rank_i is the rank
 * of document d in result list i (1-based).
 *
 * @param bm25Results - Results from BM25 search, ordered by score
 * @param semanticResults - Results from semantic search, ordered by similarity
 * @param topK - Number of results to return
 * @param k - RRF constant (default 60)
 * @returns Merged results sorted by RRF score
 */
export declare function hybridRank(bm25Results: SearchResult[], semanticResults: SearchResult[], topK: number, k?: number): SearchResult[];
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