[hts-users:03711] Re: about HERest mixture weight flooring option

[Sebastien Le Maguer <Sebastien.Le_maguer@xxxxxxxx>]

Hello,

yes I understand. Thank you for the answer and the explanation.

Kind regards,
Sébastien Le Maguer

At Tue, 16 Apr 2013 15:41:50 +0100,
Heiga ZEN (Byung Ha CHUN) wrote:
> 
> Hi,
> 
> 2013/4/16 Sebastien Le Maguer <Sebastien.Le_maguer@xxxxxxxx>:
> 
> > in the reestimation stages of the Training.pl script, I've found that the mixture weight flooring
> > option is called twice. The first one in the $HERest{'ful'} definition (Training.pl, line 213). The
> > second one for each full model reestimation stage in the "$opt" definition (Training.pl, lines 471
> > and 544) where it is set to 0.0. Is to to disable the mixture weight flooring for these particular
> > stages? If so, is there a specific reason to do this?
> 
> This is done just before the clustering stage.  In the decision
> tree-based context clustering process, statistics (occupancy counts,
> 1st and 2nd-order statistics) are first recovered from the stats file,
> means and variances (please check Odell's PhD thesis for details).  If
> you use flooring (both mixture weights or variances), recovered
> statistics are somewhat biased; you cannot recover true, original
> accumulated statistics once you perform flooring.  To avoid this
> problem, the HTS training script does not perform mixture-weight and
> variance flooring just before the tree-based context clustering stage.
> 
> I hope this explanation makes sense.
> 
> Heiga
> 
> --
> Heiga ZEN (in Japanese)
> Byung Ha CHUN (in Korean)
> <heigazen@xxxxxxxxxx>
>