/**
 * Reciprocal Rank Fusion (RRF)
 *
 * Combines multiple ranked result sets into a single fused ranking.
 * Used to merge FTS5 (keyword) and vector (semantic) search results.
 *
 * Algorithm: score(d) = Σ 1/(k + rank_i(d)) for each ranking i
 * where k is a smoothing constant (default: 60)
 */
/**
 * A ranked result set identified by document ID.
 */
export interface RankedResult {
    documentId: string;
    rank: number;
}
/**
 * Fused result with combined RRF score.
 */
export interface FusedResult {
    documentId: string;
    score: number;
}
/**
 * Combine multiple ranked result sets using Reciprocal Rank Fusion.
 *
 * @param rankings - Array of ranked result sets (each sorted by relevance)
 * @param k - Smoothing constant (default: 60, standard value from literature)
 * @param limit - Maximum results to return
 * @returns Fused results sorted by combined score (descending)
 */
export declare function reciprocalRankFusion(rankings: RankedResult[][], k?: number, limit?: number): FusedResult[];
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