readme

dbacl是一个通用目的的digramic贝叶斯文本分类器。它可以学习你提供的文本

		DBACL - digramic Bayesian classifier

PURPOSE

dbacl is a command line program which can be used to categorize
several types of text documents. Each document category is
constructed as a maximum entropy language model, with respect to
a reference measure based on digrams (character pairs).

Before recognition can take place, a number of text corpora must 
be "learned". For example, an English category could be based on 
a text file containing the collected works of Shakespeare. The 
Gutenberg project (http://promo.net/pg/) makes freely available
many public domain works in electronic form.

After learning, any number of text files can be compared, in terms 
of Bayesian posterior probabilities, with up to 128 learned categories.
The actual number of categories is limited only by available memory.

dbacl is bundled with a few other utilities:

- bayesol is a postprocessor which takes the dbacl output and computes
  an optimal decision based on costs of misclassification. Together with
  dbacl, this allows the construction of sophisticated, multilingual, 
  classification scripts, if you're not afraid of some shell scripting.

- mailcross performs email classification cross validation. It can be used
  to assess the performance of custom email classification scripts based on
  dbacl and bayesol.

- mailinspect reads an mbox style mail folder and displays the emails in sorted
  order, based on similarity to any given category. 
 
DOCUMENTATION

See the bundled manpage. Generic instructions can be found in the file INSTALL.
A tutorial is to be found in the file tutorial.html, and an exposition of 
the algorithms is in dbacl.ps. 

LICENSE

DBACL is distributed under the terms of the GNU General Public License (GPL)
which can be found in the file COPYING. The hash function code used in the 
file jenkins.c is public domain, by Bob Jenkins.

BUILDING

There are several configuration options you can change in the file dbacl.h,
if you want to increase the maximum number of categories or optimize
hash table overhead. 

To build and install the program, you can execute the following steps from
within the source DBACL directory:

./configure
make
make install 

The last part should be executed with superuser privileges for system wide
installation. Alternatively

./configure --prefix=/home/xyzzy
make 
make install

builds and installs in user xyzzy's home directory, without the need for
root privileges. In this case, the following environment variables 
should be set permanently (e.g. in the file .profile):

PATH=$PATH:/home/xyzzy/bin
MANPATH=$MANPATH:/home/xyzzy/man

INTERNATIONALIZATION

dbacl uses the current locale for processing. 8-bit clean multibyte 
character sets (such as UTF-8) are supported in the default mode, 
and arbitrary multibyte character sets require the -i command line option. 
If you intend to use the -i option together with regular expressions,
you must build with a wide character POSIX regex library: ensure that
the BOOST library is present on the system and type

./configure WIDE_REGEX=1
make 
make install

Warning: there is a large performance penalty if you build dbacl this way,
which shows up whenever you use regular expressions. Only build this way if
you need correct regular expressions in a multibyte environment which isn't 
8-bit clean.

OTHER DEPENDENCIES

The main filter programs dbacl and bayesol have no special dependencies, and
can always be compiled. 

mailinspect uses the readline and slang libraries for screen management in
interactive mode. The configure script will check for these libraries and 
if it can't find them, mailinspect will be compiled without interactive support. 

mailcross is a bash shell script which calls awk and formail at various
points. It will test for the existence of these programs in your path and
refuse to run if it can't find them.

RUNNING

There is a tutorial which you can read with any web browser, point it to the
file tutorial.html. For command line options and examples of possible use, 
type after installation: 

man dbacl
man bayesol
man mailcross
man mailinspect

You can also find a technical description of the algorithms and statistics
in the postscript file dbacl.ps

TUTORIAL SAMPLES

The tutorial.html document comes with several sample text files:

- sample1.txt and sample4.txt are extracts from Mark Twain, Huckleberry Finn
- sample2.txt, sample3.txt, sample5.tx are extracts from Douglas Adams, 
  The Hitchhikers' Guide to the Galaxy

AUTHOR

Laird A. Breyer <[e-mail]>