code: public static long scalarProduct(final Modulo2Equation e, long[] solution) {
  			long sum = 0;
  			for(final IntListIterator iterator = e.variables.iterator(); iterator.hasNext();)
  				sum ^= solution[iterator.nextInt()];
  			return sum;
  		}
docs: Returns the modulo-2 scalar product of the two provided bit vectors.
  
  @return the modulo-2 scalar product of {@code e} and {code f}.