fregejs/src/utils/haveEvenNumberOfNegations.ts

A propositional logic library written in Typescript

import { eliminateDoubleNegations } from './eliminateDoubleNegation';
import { isNegation } from './isNegation';
import { Formula } from 'types/formulas/formula';

export function haveEvenNumberOfNegations(formula: Formula) {
  if (!isNegation(formula)) return true;

  formula = eliminateDoubleNegations(formula);
  return !isNegation(formula);
}