====== Bayes Rule ======

$P(A|B) = \frac{P(B|A) P(A)}{P(B)}$

  * A: 원인 또는 가정(Hypothesis) -> P(A): 사전확률(Priori)
  * B: 관찰 또는 관측(Observation) -> P(A): 사전확률(Evidence)

$P(hypothesis|observation) = \frac{P(observation|hypothesis) P(hypothesis)}{P(observation)}$

$posterior = \frac{likelihood \times priori}{evidence}$

$P(\theta_j|X) = \frac{P(X|\theta_j) P(\theta_j)}{\sum_j{P(X|\theta_j)P(\theta_j)}} = \frac{P(X|\theta_j) P(\theta_j)}{P(X)}$

  * $X$ 데이터
  * $\theta_j$: 카테고리
  * $P(\theta_j|X)$: 사후확률(posteriori)
  * $P(X|\theta_j)$: 우도(likelihood)
  * $P(X)$: 증거(Evidence), 정규화된 상수로 취급 또는 무시

  * http://www.ktword.co.kr/abbr_view.php?nav=&m_temp1=3730&id=887
  * http://www.ktword.co.kr/abbr_view.php?m_temp1=4215