import { IContextFreeGrammar, IContextFreeGrammarInput } from './types';
export declare function createProductionCombinations(substitution: string, epsilonProducingVariable: string, productionRuleVariable: string): readonly [string[], boolean, number];
/**
 * Adds epsilon to production rules that references nullable variables
 * @param cfg Variables array and production rules record of cfg
 */
export declare function findNullableVariables(cfg: Pick<IContextFreeGrammar, 'variables' | 'productionRules'>): string[];
/**
 * Removes all the null production and returns a new transition record
 * @param cfg Variables and transition record for cfg
 * @returns New transition record with null production removed
 */
export declare function removeNullProduction(inputCfg: Pick<IContextFreeGrammarInput, 'variables' | 'productionRules' | 'startVariable'>): void;