BAYESOL(1)																BAYESOL(1)

NAME

       bayesol - a Bayes solution calculator for use with dbacl.

SYNOPSIS

       bayesol [-DVNniv] -c riskspec [FILE]...

       bayesol -V

DESCRIPTION

       bayesol	is  a Bayes solution calculator designed to combine the output of dbacl(1) with a prior distribution and a risk specification, and
       calculate the optimal Bayesian decision (which minimizes the posterior risk).

       The risk specification is read from the text file riskspec and must be written in a simple format described below. The dbacl(1) output  can
       either be read from FILE or from STDIN.

EXIT STATUS

       On  success,  bayesol returns a positive integer corresponding to the category with the lowest risk.  In case of a problem, bayesol returns
       zero.

OPTIONS

       -c     Classify using riskspec.	See the section RISK SPECIFICATION.

       -i     Fully internationalized mode. Forces the use of wide characters internally, which is  necessary  in  some  locales.  This  incurs  a
	      noticeable performance penalty.

       -n     Print risk scores for each category.  Each score is (approximately) the logarithm of the expected risk under that category. The low-
	      est score (ie closest to -infinity) is best, etc.

       -N     Print recursive risk scores for each category.  Each score is (approximately) the logarithm of the best score based on the remaining
	      categories,  after  the previously best scoring categories have been removed, and a normalizing factor was added. A full description
	      is given in the technical report listed at the end of this manpange. The largest score (ie closest to +infinity) is best, etc.

       -v     Verbose mode. Prints to STDOUT the category with minimum posterior risk.	In case several categories are possible, prints the  first
	      category in the order in which they appear in the categories section of riskpspec.

       -D     Print debug output. Do not use.

       -V     Print the program version number and exit.

RISK SPECIFICATION

       bayesol needs to read a text file riskspec containing a risk specification. The format of this text file is as follows

	      categories { cat1, cat2,..., catN}
	      prior { p1, p2,..., pN}
	      loss_matrix {
	      "regex1" c1 [ formula11, formula12,..., formula1N]
	      "regex2" c2 [ formula21, formula22,..., formula2N]
	       .
	       .
	      "regexM" cM [ formulaM1, formulaM2,..., formulaMN]
	      }

       In the above, cat1, cat2,..., catN, are category names, p1, p2,..., pN, are non-negative numbers, regex1, regex2,..., regexM, are (possibly
       empty) regular expression strings, c1, c2,..., cM, are instances of the category names cat1, cat2,..., catN, and the formulas  are  numbers
       or mathematical expressions.

       Every  category	which  appears	in  the  categories section must appear at least once in the loss_matrix section, with an empty "" regular
       expression.  To construct the actual loss matrix used in the decision calculations, bayesol selects, for each  category	appearing  in  the
       categories  section, the first row whose regular expression is matched within FILE or STDIN, or the first row with empty regular expression
       if there are no matches.

       Each formula can be either a single number, or an algebraic combination of the operators exp(), log(), +, -, *, /, ^  and  parentheses  ().
       The  string  "inf"  is  parsed as the value infinity. Also, the string "complexity" is recognized, and converted to the complexity for that
       category as reported by dbacl(1).  Finally, if the corresponding regular expression contains submatches	delimited  by  parentheses,  their
       numerical values can be used inside the formulas as the special variables $1, ..., $9. Note that submatches which aren't numerical are con-
       verted to the value zero.

       Case is important. Spaces and newlines can be liberally inserted. Comments must start with a # and extend to the end of the line.

USAGE

       Typically, bayesol is used together with dbacl(1).  An invocation looks like this:

       % dbacl -c one -c two -c three sample.txt -vna | bayesol -c toy.risk -v

       See /usr/share/doc/dbacl/costs.ps for a description of the algorithm used.  See also /usr/share/doc/dbacl/tutorial.html for a more detailed
       overview.

SOURCE

       The source code for the latest version of this program is available at the following locations:

       http://www.lbreyer.com/gpl.html
       http://dbacl.sourceforge.net

AUTHOR

       Laird A. Breyer <laird@lbreyer.com>

SEE ALSO

       dbacl(1), mailcross(1), mailfoot(1), mailinspect(1), mailtoe(1), regex(7)

Version 1.12						   Bayesian Classification Tools						BAYESOL(1)