Изменения

= \frac{\alpha_s(t)\cdot \beta_s(t)}{\sum_{i \in S}\alpha_s(t)\cdot \beta_s(t)}</tex>

fwd = {}

bkw = {}

fwd[s, 1] = emit_probability[s][observations[1]] * П[s]

bkw[s, len(observations) - 1] = 1

alpha(s, t):

if (s, t) in fwd: return fwd[s, t]