paper available on diploid neural networks

[Raffaele Calabretta]

The following paper (to appear in Neural Processing Letters) is now 
available via anonymous ftp:

-------------------------------------------------------------------------

      "Two is better than one: a diploid genotype for neural networks"
       ---------------------------------------------------------------     
       
Raffaele Calabretta (1,3), Riccardo Galbiati (2), Stefano Nolfi (1) and
Domenico Parisi (1)

1 Department of Neural Systems and Artificial Life 
Institute of Psychology, National Research Council
e-mail: raffaele at caio.irmkant.rm.cnr.it

2 Department of Biology, University "Tor Vergata"

3 Centro di Studio per la Chimica del Farmaco, National Research Council
Department of Pharmaceutical Studies, University "La Sapienza"

                  Rome, Italy

---------------------------------------------------------------------------
                              Abstract:

  In nature the genotype of many organisms exhibits diploidy, i.e., it
includes two copies of every gene. In this paper we describe the results 
of simulations comparing the behavior of haploid and diploid populations 
of ecological neural networks living in both fixed and changing environments. 
We show that diploid genotypes create more variability in fitness in the
population than haploid genotypes and buffer better environmental change; 
as a consequence, if one wants to obtain good results for both average and 
peak fitness in a single population one should choose a diploid population 
with an appropriate mutation rate. Some results of our simulations parallel
biological findings. 

Key words: adaptation, diploidy, genetic algorithms, genotype-phenotype 
mapping, neural networks.
_________________________________________________________________


FTP-host:  gracco.irmkant.rm.cnr.it
FTP-filename:  /pub/raffaele/calabretta.diploidy.ps.Z 

The paper has been placed in the anonymous-ftp archive
(see above for ftp-host) and is now available as a compressed 
postscript file named: calabretta.diploidy.ps.Z

Retrieval procedure:

     unix> ftp gracco.irmkant.rm.cnr.it
     Name: anonymous  Password: {your e-mail address}
     ftp>  cd pub/raffaele
     ftp>  bin
     ftp>  get calabretta.diploidy.ps.Z
     ftp>  quit
     unix> uncompress calabretta.diploidy.ps.Z

e.g. unix> lpr calabretta.diploidy.ps  (8 pages of output)

The paper is also available on World Wide Web:
http://kant.irmkant.rm.cnr.it/gral.html

Comments welcome
  Raffaele Calabretta

e-mail address:                   raffaele at caio.irmkant.rm.cnr.it