Print

---

Hi,

I am looking for 'sparse kernels' : kernels which are *exactly* zero for most of
the elements of the kernel matrix. Assume k(a,b) is a kernel function, then
two ways to build such kernels are :

(a) k'(a,b) = max { k(a,b)-q, 0} for some q>=0

                {  k(a,b)   if k(a,b)>q
(b) k'(a,b) =   {
                {  0        otherwise


for some q>=0 (the second method is not continuous)

Does anyone know if any of these methods yield a valid kernel function for
any k(.,.)? for the RBF kernel function? Is there a sparse kernel function (not
built this way)?


Thanks, Koby

============================================
Koby Crammer            [log in to unmask]

http://www.cs.huji.ac.il/~kobics
============================================