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PISA  (www.tik.ee.ethz.ch/pisa/)
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Computer Engineering (TIK)
ETH Zurich	 
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SPAM - Set Preference Algorithm for Multiobjective Optimization

Implementation in C for the selector side.

Documentation
  
author: Johannes Bader, johannes.bader@tik.ee.ethz.ch
last change: 27.07.2009
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The Optimizer
=============

SPAM is a multiobjective evolutionary algorithm to incorporate preference and has been
proposed by Eckart Zitzler, Lothar Thiele, and Johannes Bader at the ETH Zurich. 
Here, we present a PISA-implementation of the algorithm based on the cited paper

@Article{	  ztb2008d,
	author={E. Zitzler and L. Thiele and J. Bader},
	title={{On Set-Based Multiobjective Optimization}},
	journal={IEEE Transactions on Evolutionary Computation},
	year={2009},
	note={to appear}
}


The Parameters
==============

SPAM uses the following values for the common parameters.
These parameters are specified in 'PISA_cfg'.

alpha    (population size)
mu       (number of parent individuals)
lambda   (number of offspring individuals)
dim      (number of objectives)



SPAM takes three local parameter which is given in a parameter
file. The name of this parameter file is passed to SPAM as command
line argument. (See 'SPAM_param.txt' for an example.)

seed 34640576
bound 1.2
prefreltype 6


seed         (seed for the random number generator)
bound        (upper bound defining the reference point as r = (bound, ..., bound) )
prefreltype  (type of preference relation, corresponding to the Figures in [ztb2008d] )
        		1: minpart + H
			2: minpart + P1 + H
			3: minpart + R2 + H
			4: minpart + eps1 + H
			5: minpart + P0 + H
			6: minpart + D


Source Files
============

The source code for SPAM is divided into multiple files.

Additionally a Makefile, a PISA_configuration file with common
parameters and a PISA_parameter file with local parameters are
contained in the tar file.

Depending on whether you compile on Windows or on Unix (any OS having
<unistd.h>) uncomment the according '#define' in the 'spam.h' file.


Usage
=====

Start SPAM with the following arguments:

spam paramfile filenamebase poll

paramfile: specifies the name of the file containing the local
parameters (e.g. SPAM_param.txt)

filenamebase: specifies the name (and optionally the directory) of the
communication files. The filenames of the communication files and the
configuration file are built by appending 'sta', 'var', 'sel','ini',
'arc' and 'cfg' to the filenamebase. This gives the following names for
the 'PISA_' filenamebase:

PISA_cfg - configuration file
PISA_ini - initial population
PISA_sel - individuals selected for variation (PISA_
PISA_var - variated individuals (offspring)
PISA_arc - individuals in the archive


Caution: the filenamebase must be consistent with the name of
the configuration file and the filenamebase specified for the SPAM
module.

poll: gives the value for the polling time in seconds (e.g. 0.5). This
      polling time must be larger than 0.01 seconds.




Limitations
===========

None limitations are known so far.



Stopping and Resetting
======================

The behaviour in state 5 and 9 is not determined by the interface but
by each variator module specifically. SPAM behaves as follows:

state 5 (= variator terminated): set state to 6 (terminate as well).
state 9 (= variator resetted): set state to 10 (reset as well).