Editing Statistical learning theory (section)

===Regression===
The most common loss function for regression is the square loss function (also known as the [[L2-norm]]). This familiar loss function is used in [[Ordinary least squares regression|Ordinary Least Squares regression]]. The form is:
<math display="block">V(f(\mathbf{x}),y) = (y - f(\mathbf{x}))^2</math>

The absolute value loss (also known as the [[L1-norm]]) is also sometimes used:
<math display="block">V(f(\mathbf{x}),y) = |y - f(\mathbf{x})|</math>