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A Unified View of Kernel k-means, Spectral Clustering and Graph Cuts. Dhillon, Inderjit S., Yuqiang Guan, and Brian Kulis. K means and Kernel K means. Weighted Kernel k means. Matrix Form. Spectral Methods. Spectral Methods. Represented with Matrix. Ratio assoc. Ratio cut. L for Ncut.
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A Unified View of Kernel k-means, Spectral Clustering and Graph Cuts Dhillon, Inderjit S., Yuqiang Guan, and Brian Kulis
Weighted Kernel k means Matrix Form
Represented with Matrix Ratio assoc Ratio cut L for Ncut Norm assoc
Weighted Graph Cut Weighted association Weighted cut
Conclusion • Spectral Methods are special case of Kernel K means
Solve the uniformed problem • A standard result in linear algebra states that if we relax the trace maximizations such that Y is an arbitrary orthonormal matrix, then the optimal Y is of the form Vk Q, where Vk consists of the leading k eigenvectors of W1/2KW1/2 and Q is an arbitrary k × k orthogonal matrix. • As these eigenvectors are not indicator vectors, we must then perform postprocessing on the eigenvectors to obtain a discrete clustering of the point
From Eigen Vector to Cluster Indicator 1 2 Normalized U with L2 norm equal to 1
The Other Way • Using k means to solve the graph cut problem: (random start points+ EM, local optimal). • To make sure k mean converge, the kernel matrix must be positive definite. • This is not true for arbitrary kernel matrix
The effect of the regularization ai is in ai is not in