# knot theory – White’s equation in original paper

I’m reading this paper and I just want to understand a part of it.

In the section 2, page 698, I understand he’s working in his equation (known as the White’s equation)

$$Lk(K,K’)=Tw(K,K’)+Wr(K),$$

but I don’t get why if $$K'(t)=K(t)+epsilon v(t)$$ with $$0 small enough such that $$K$$ and $$K’$$ never overlap I can say that I’m calculating the Writhe of the curve $$K$$?

Sorry in advance if the question is simple, but I don’t understand well the notation and I have never used differential forms.