Let $ E: y^2=x^3+ax^2+bx+c $ be an elliptic curve over $Q$ which have discriminant $\Delta\neq 0$ and conductor $N$ And we have this notation
$Ord_{2}(\Delta) $ or $ord_{2}(b)$
$V_{l}(\Delta)$
What do we mean by these two notations above? And what are their roles?
And give an example of them in this curve $$E:y^2=x^3-x^2+1$$