Classification Models

$p(y=c|x,\theta) = \frac{p(x|y=c,\theta)p(y=c|\theta)}{\Sigma_{c'}{p(x|y=c',\theta)p(y=c'|\theta)}}$

Note:

• Prior $p(y=c|\theta) = \pi_c$
• Class conditional density $p(x|y=c,\theta)$
• Generative classifier

Discriminative classifiers directly model $p(y|x,\theta)$