/**
 * How little a word that EVERY entry carries may count. A floor, not zero,
 * because a common word still has to be worth something — "page" must still
 * find `ed-page`. Chosen in #2080 on measurements: routing was flat from 0.25
 * down to 0.15, and the first benchmark regression appeared at 0.
 */
export declare const RARITY_FLOOR = 0.25;
export interface TermWeights {
    /** A multiplier in `[RARITY_FLOOR, 1]` for one query term; plurals share their singular's. */
    weightOf(term: string): number;
}
/**
 * Round a weighted score to nine decimal places. Weighted sums that are equal on
 * paper (0.1 + 0.2 + 0.3 and 0.3 + 0.2 + 0.1) differ in their last binary digit,
 * which was enough to stop two tied entries ever reaching the rankers' tiebreaks.
 */
export declare const settle: (score: number) => number;
/** Every word counts the same — the behaviour before #2080, and the default when no weights are passed. */
export declare const UNWEIGHTED: TermWeights;
/** The slice of a catalog entry that says what the entry IS. */
export interface WeightableEntry {
    tagName: string;
    displayName?: string;
    intent?: string;
    guidelines?: {
        use?: string[];
        useWhen?: string[];
    };
}
/**
 * Build the weights for a catalog. `weight = floor + (1 - floor) × idf`, where
 * `idf = ln((N + 1) / (df + 1)) / ln(N + 1)` runs from 1 (no entry carries the
 * word) towards 0 (every entry does). An entry counts once per word however
 * often it says it.
 */
export declare function buildTermWeights(entries: WeightableEntry[], floor?: number): TermWeights;
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