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In page 206 of the book 'Elements of statistical learning', the author wrote:

The local log-likelihood for this $J$ class model can be written

$\sum_{i=1}^NK_\lambda (x_0, x_i)\{\beta_{g_i0}(x_0) + \beta_{g_i}(x_0)^T(x_i-x_0) - log[1+\sum_{k=1}^{J-1}exp(\beta_{k0}+\beta_k(x_0)^T(x_i-x_0))]\}$

I can understand that the term $K_\lambda (x_0, x_i)$ is there to weight down the log-likelihood of each individual observation, but really don't know why the term $(x_i-x_0)$ instead of only $x_i$ - which I am expecting.

Is this just a typo or am I misunderstanding something?

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Three bullets below, the authors provide the answer:

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  • $\begingroup$ I saw it couple days ago, since I cannot vote up now, thanks for your attention $\endgroup$
    – Learner
    Commented Jun 2, 2014 at 4:50

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