Hi,
all
I am studying
the source code of HERest of HTS 2.2 these days. The implemented code seems to
be some recursion form of the original formula in literature
[1].
A. Backward
algorithm in literature
Initial:
.
Recursion:
B. Backward
algorithm in source code
Initial:
Recursion:
Termination:
My problems
are: 1) what is the definition of 
as appeared in the source
code? 2) Is there any material deriving the formula implemented in
code?
Thank
you in advance!
Yang
Wang
[1] Zen, H., Tokuda, K., Masuko, T. et al., “A Hidden Semi-Markov
Model-Based Speech Synthesis System”, IEICE Transactions on Information and
Systems E series D, vol. 90, no. 5, pp. 825-834,
2007.