This is Perl module Lingua::JA::OkapiBM25.

INSTALLATION

Lingua::JA::OkapiBM25 installation is straightforward. If your CPAN shell is set up,
you should just be able to do

    % cpan Lingua::JA::OkapiBM25

Download it, unpack it, then build it as per the usual:

    % perl Makefile.PL
    % make && make test

Then install it:

    % make install

DOCUMENTATION

Lingua::JA::OkapiBM25 documentation is available as in POD. So you can do:

    % perldoc Lingua::JA::OkapiBM25

to read the documentation online with your favorite pager.

Takeshi Miki