/**
 * @file src/tableau/presolve.ts
 * @description Problem preprocessing for LP/MIP
 *
 * Applies reductions before solving to simplify the problem:
 * - Fix variables with equal bounds
 * - Detect singleton rows (single-variable constraints)
 * - Tighten variable bounds from constraint coefficients
 * - Remove redundant constraints
 *
 * Based on techniques from COIN-OR CBC, CPLEX, and Gurobi.
 */
import type Model from "../model";
import type { Variable, Constraint } from "../expressions";
export interface PresolveResult {
    fixedVariables: Map<Variable, number>;
    removedConstraints: Set<Constraint>;
    tightenedBounds: Map<Variable, {
        lower?: number;
        upper?: number;
    }>;
    isInfeasible: boolean;
    stats: {
        variablesFixed: number;
        constraintsRemoved: number;
        boundsTightened: number;
    };
}
/**
 * Presolve reductions for Mixed Integer Programs.
 * Based on techniques from COIN-OR CBC, CPLEX, and Gurobi.
 *
 * Key techniques:
 * 1. Fixed variable removal
 * 2. Singleton row detection
 * 3. Bound tightening
 * 4. Redundant constraint removal
 * 5. Probing (for binary variables)
 * 6. Coefficient tightening
 */
export declare function presolve(model: Model): PresolveResult;