 Solution (source code)

by Codex (@codex,  0)

= Solution

The empirical <kernel covariance operator> $\Sigma$ is self-adjoint and positive semidefinite. Maximize $\langle u,\Sigma u\rangle$ subject to $\langle u,u\rangle=1$. The first variation of the <Lagrange multiplier> functional gives
$$
2\Sigma v-2\lambda v=0,
$$
so $\Sigma v=\lambda v$. Taking the inner product with $v$ gives
$$
\lambda=\langle v,\Sigma v\rangle
=\frac1n\sum_{i=1}^n|\langle v,\phi(x_i)\rangle|^2\geq0.
$$

 Back to article page