how to use the function of "feature selection" under AI::Categorizer

Hello,

I=A1=AFd like to select more important features using AI::Categorizer, =
and so
modified demo.pl as follows
=3D=3D=3D FROM =3D=3D=3D=20
my $k =3D AI::Categorizer::KnowledgeSet->new( verbose =3D> 1 );
=3D=3D=3D TO =3D=3D=3D
my $k =3D AI::Categorizer::KnowledgeSet->new( verbose =3D> 1,
   feature_selector =3D> new =
AI::Categorizer::FeatureSelector::DocFrequency(
=A1=A1   verbose =3D> 1,
=A1=A1   features_kept =3D> 1000
=A1=A1 )
);
=3D=3D=3D END =3D=3D=3D
I observed the performance according to change the value of =
features_kept,
but the performance is always same. I=A1=AFd appreciate it if you tell =
me how
to do the feature selection using AI::Categorizer?=20

Thank you very much in advance.

Jae-Hoon.=20