2nd Order Swarm Intelligence
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2nd Order Swarm Intelligence

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Presentation by David M.S. Rodrigues on a novel algorithm for Ant Colony System that includes a negative pheromone that acts as a non-entry signal for unrewarding paths in the Travelling Salesman ...

Presentation by David M.S. Rodrigues on a novel algorithm for Ant Colony System that includes a negative pheromone that acts as a non-entry signal for unrewarding paths in the Travelling Salesman Problem (TSP)

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2nd Order Swarm Intelligence 2nd Order Swarm Intelligence Presentation Transcript

  • 2nd  Order  Swarm  Intelligence   Vitorino  Ramos,  David  Rodrigues+,  and  Jorge  Louçã     HAIS  2013,  Salamanca   September  11-­‐13,  2013   hHp://goo.gl/OXc0Oh     +  The  Open  University,  UK  –  david.rodrigues@open.ac.uk  
  • Outline   •  Present  an  algorithm  that  is  an  extension  to   Ant  Colony  System   •  Use  of  non-­‐entry  signal  via  a  negaSve   pheromone.   •  Use  of  2  pheromones  improves  quality  of   results  
  • Ant  Colony  OpSmisaSon   •  ProbabilisSc  technique   •  Searching  for  OpSmal  Path  in  the  graph   (Based  on  the  behaviour  of  ants  seeking  a   path  between  colony  and  source  of  food)   •  Mata-­‐heurisSc  opSmisaSon  
  • ACO  Concept     •  Ants  navigate  from  nest  to  food  source.   Blindly!   •  Shortest  path  is  discovered  via  pheromone   trails  deposited  by  other  ants.   •  Each  ant  moves  stochasScally   •  Pheromone  is  deposited  on  path   •  More  pheromone  implies  higher  probability  of   path  being  followed.  
  • ACO  IllustraSon  
  • TSP  Problem   •  A  Salesman  must  visit  N  ciSes,  passing   through  each  city  only  once,  and  returning  to   the  start  city.   •  The  cost  of  the  transportaSon  between  all   ciSes  is  known   •  The  ObjecSve  is  to  choose  the  order  of  the   tour  so  the  total  cost  is  minimum.  
  • History   •  Ant  System  developed  by  Marco  Dorigo  (1992,   PhD  thesis)   •  Max-­‐Min  Ant  System  by  Hoos  and  Stützle   (1996)   •  Ant  Colony  by  Gambardella,  Dorigo  (1997)  
  • Biology  Findings  of  non-­‐entry  singals   •  Pharaoh's  ants  (Monomorium  pharaonis)   deposit  a  pheromone  as  a  'no  entry'  signal  to   mark  unrewarding  foraging  paths.   [Robinson,  2005,  2007;  Grüter  2012]  
  • 2nd  Order  Swarm  Intelligence   •  Double  Pheromone  Model  on  top  of   tradiSonal  ACS.   – TradiSonal  posiSve  reinforcement  pheromone   – Use  of  NegaSve  Pheromone   •  Marker  for  forbidden  paths   •  Forbidden  paths  are  obtained  from  the  worse  ant  tour   of  each  iteraSon   •  This  Blockade  isn’t  permanent  as  the  pheromone   evaporates.  
  • State  TransiSon  Rule  
  • State  TransiSon  Rule  
  • Global  UpdaSng  Rule  
  • Local  UpdaSng  Rule  
  • 2nd  Order  Reasoning  
  • 2nd  Order  Response  Maps  
  • 2nd  Order  AS  Results  
  • Influence  of  NegaSve  Pheromone  
  • kroA100.tsp  with  negaSve  pheromone   performs  beHter  
  • NegaSve  Pheromone  Also  is  important   for  bigger  problems.  
  • NegaSve  pheromone  can’t  dominate   the  pheromone  maps.  
  • Take  Home  Message   •  From  Biology  Findings:  use  of  negaSve   pheromone  as  non-­‐entry  signal   •  New  algorithm  based  on  ACS  with  minimal   changes  to  tradiSonal  algorithm   •  BeHer  results  (faster  convergence  to  good   results/  faster     •  ApplicaSon  to  Dynamical  problems  for  faster   tracking  of  the  soluSons.