import type { PropFormula } from "../../../models";
/**
 * Introduces an equivalence (A <=> B) given two implications (A => B) and (B => A).
 *
 * @param formulas An array of propositional formulas.
 * @returns {[PropFormula]} A tuple containing the inferred formula.
 * @throws {Error} if the input formulas do not satisfy the equivalence introduction conditions.
 */
export declare function equivalenceIntroduction(formulas: PropFormula[]): [PropFormula];