========================================================================
PISA  (www.tik.ee.ethz.ch/pisa/)
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Computer Engineering (TIK)
ETH Zurich	 
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SHV - Sampling-based HyperVolume-oriented Algorithm

Implementation in C for the selector side.

Documentation
  
file: shv_documentation.txt
author: Johannes Bader, johannes.bader@tik.ee.ethz.ch
last change: 20.04.2009
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The Optimizer
=============

SHV is a hypervolume-based algorithm that uses Monte-Carlo sampling to
approximate the hypervolume contributions of individuals. 

@InProceedings{	  bdz2008a,
	author={J. Bader and K. Deb and E. Zitzler},
	title={{Faster Hypervolume-based Search using Monte Carlo Sampling}},
	booktitle={Conference on Multiple Criteria Decision Making (MCDM~2008)},
	year={2008},
	publisher={Springer},
	note={to appear},
	location={Auckland, New Zealand}
}

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

SHV 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)



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

seed         (seed for the random number generator)
bound        (bound used as reference point by the hypervolume indicator)
junks        (maximum number of sampling steps)
junksize     (number of samples per step)



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

The source code for SHV is divided into four files:

'shv.h' is the header file.

'shv.c' contains the main function and implements the control flow.

'shv_io.c' implements the file i/o functions.

'shv_functions.c' implements all other functions including the
                  selection.

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 'shv.h' file.


Usage
=====

Start SHV with the following arguments:

shv paramfile filenamebase poll

paramfile: specifies the name of the file containing the local
parameters (e.g. shv_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 SHV
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. SHV 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).