Machine Learning, Kernel, Hilbert Space, Mercer Theorem.
dimensional space. Let the features in that space be f (x) = (x1x1, x1x2, x1x3, x2x1, x2x2, x2x3, x3x1, x3x2, x3x3). For our vectors, features are φ(x) = (1, 2, 3, 2, 4, 6, 3, 6, 9) and φ(y) = (16, 20, 24, 20, 25, 30, 24, 30, 36). Finally, there dot product is (φ(x), φ(y))=