I was told that Gradient Descent finds the weights of smallest norm.
This is what I understood in the linear regression setting:
$f_w(x)=w^\top x$ are the linear functions $ \mathbb{R}^n \rightarrow \mathbb{R} $.
$ \mathcal{D}=\{(x_i,y_i) \in \mathbb{R}^d\times\mathbb{R} \mid i=1,...,n\} $ is a dataset
Then I choose some loss function $L$, then some cost function $C_0$ such that $ C_0(w)=\frac{1}{n} \sum_i L(f_w(x_i),y_i) $
Finally, I defined a regularized cost $ C_\lambda(w)=C_0(w)+\frac{\lambda}{2n}||w||^2 $
Then there must be some sort of equivalence between (and it looks it should be some classical result):
- minimizing $C_\lambda(w)$ for an opportune $ \lambda \ge 0 $
- minimizing $C_0(w)$ with Gradient Descent
My questions:
- Can somebody clarify a bit this fact? By providing some hypothesis (e.g. on $L$), some insight, some reference...
- Does this apply in a similar way to the linear classification setting ($y_i\in\{-1,+1\}$)? In that case, I would expect some equivalence bewteen:
- maximizing $M(w)= \min_{i=1...n} y_i \langle w, x_i \rangle $ over $||w||=1$
- minimizing $||w||$ over $ y_i \langle w, x_i \rangle \ge 1 $
- maybe the previous 1. and 2. points above (those regarding regression)