If the kernel k is positive definite for any pair of examples x and z, the determinant of the gram matrix is not negative.
|k(x, x) k(x, z)|
| | = k(x,x)k(z,z) - k(x,z)^2 >= 0
|k(z, x) k(z, z)|
For distance (including distance from interference), the following properties are stored:
For any x, y:
1) d(x, z) >= 0 and d(x, z) = 0 <=> x = z
2) symmetry d(x, z) = d(z, x)
3) triangular inequality d(x, z) <= d(x, y) + d(y, z)
Given that k is the distance from the interference, according to 1), we would have:
a) k(x,x) = k(z,z) = 0
But in order to be an explicit core, we need:
b) k(x,x)k(z,z) - k(x,z)^2 >= 0
a) b), :
-k(x,z)^2 >= 0
k(x,z)^2 <= 0
, k (x, z) , , .
- , , , : K ( "aab", "baa" ) = [0,1,0,1,1,0]\dot [1,0,0,1,0,1].
, .
"aab" "baa" 2, .
[0,1,0,1,1,0] \dot [1,0,0,1,0,1] = 1.
, , SVM, .