Answer:
Yes, the function is a kernel
Step-by-step explanation:
Given
Document x an z
Function definition! k(x:z)
We want to show that the above is a kernel.
To do this, we'll explicitly construct feature vectors φ(x) and φ(z)
This gives;
K(x,z) =φ(x)·φ(z).
Given than any document; say x and z
A vocabulary V can be constructed.
Vocabulary V must have a finite size of words in the document set..
The feature mapping is constructed as φ(x) for x by the following:
For the kth word wk in V, if wk appears in document x, assign φ(x) k(the kth element ofφ(x)) to be 1; else φ(x)k to 0.
Then the number of unique words common in x and z is φ(x)·φ(z), giving us the kernel
.
28 x 2 = 56 half dollar coins
