import type { PropFormula } from "../../models";
/**
 * Checks if equivalence introduction rule is applicable.
 *
 * Equivalence introduction allows us to infer an equivalence (A ≡ B)
 * if we have both implications (A → B) and (B → A).
 *
 * @param formulas - An array of propositional formulas to check.
 * @returns `true` if we can infer equivalence, otherwise `false`.
 * @category Validators
 */
export declare function isEquivalenceIntroductionApplicable(formulas: PropFormula[]): boolean;