import type { BaseEstimator } from './estimator';
export type Coefficients = number[] | number[][];
export type EstimatorCapability = 'coef' | 'featureImportances';
export interface CoefficientCapability {
    /** Fitted input-feature coefficients. A copy is returned to protect model state. */
    readonly coef: Coefficients;
}
export interface FeatureImportanceCapability {
    /** Normalized non-negative input-feature importances. */
    readonly featureImportances: number[];
}
/**
 * Capability declaration is structural: an estimator opts in by defining the
 * named public property/getter. BaseEstimator intentionally does not provide
 * placeholders, so unsupported estimators (for example kernel SVMs) remain
 * distinguishable from supported-but-unfitted estimators.
 */
export declare function declaresEstimatorCapability(estimator: BaseEstimator, capability: EstimatorCapability): boolean;
export declare function hasCoefficientCapability(estimator: BaseEstimator): estimator is BaseEstimator & CoefficientCapability;
export declare function hasFeatureImportanceCapability(estimator: BaseEstimator): estimator is BaseEstimator & FeatureImportanceCapability;
/** Flatten one- or two-dimensional coefficients into one importance per input feature. */
export declare function coefficientImportances(coef: Coefficients): number[];