  The purpose of this article is to give a preliminary clarification on the
relation between crossing number and crossing change. With a main focus on the
span of X polynomial, we prove that, as our theorem claims, the crossing number
of the link after crossing change can be estimated when certain conditions are
met. At the end of the article, we give an example to demonstrate a special
case for the theorem and a counterexample to explain that the theorem cannot be
applied if the obtained link is not alternating.
