In this paper, in the Formula at the beginning of 2.2, we have
$B=\{b_i(O_t)\}$
where
$i=0,1$ - the number of probability formula
$O_t$ - the state at moment $t$
$b_i(O_t)$ - two probabilities or estimations for the state $O_t$
The result ($B$) is named "likelihood". How can likelihood be obtained from 2 numbers? Is this a weighted average like
$b_i(O_t)= 0*b_0(O_t) + 1*b_1(O_t)$
or
$b_i(O_t)= -1*b_0(O_t) + 1*b_1(O_t)$
or something?