Thus, by preserving vectors d and − P (e)q(d|e) we can efficiently compute the dot-product in (39); the computational complexity of a kernel function is on the condition that the original dimension is larger than the number of categories.
from the viewpoint of computational time, our kernel has an advantage over some other kernels such as the PLSI-based Fisher kernel in Section 4, which requires the computational complexity of O(|I| × |C cluster |), where C cluster denotes the set of clusters.