Research Article

A Biogeography-Based Optimization Algorithm Hybridized with Tabu Search for the Quadratic Assignment Problem

Algorithm 2

BBOTS algorithm for QAP.
(1) Parameter setting: Pop.size = , Num.Iteration = 300, , , ,  elite = 2
(2) Initialization:
(3)repeat
(4)  generate a habitat
(5)  if  habitat does not exist yet  then
(6)   insert it into population
(7)  else
(8)   discard it
(9)until  population size is reached
(10) calculate immigration, emigration, and mutation rates
(11)  compute HSI of each habitat
(12) associate each habitat with immigration and emigration rate
(13) for   to Num.Iteration  do
(14)  Migration:
(15) for   to Pop.size  do
(16)   generate
(17)   if    then
(18)    for   to Pop.size  do
(19)        generate
(20)        if    then
(21)        perform migration operator
(22)        if  new habitat does not exist in the population  then
(23)         new habitat replaces old habitat
(24)        else
(25)         keeps the old habitat
(26) recompute HSI for each habitat
(27) associate each habitat with mutation rate
(28)  Mutation:
(29) for   to Pop.size  do
(30)   generate
(31)    if    then
(32)    perform tabu search
(33)    if  new habitat does not exist in the population  then
(34)        new habitat replace the old habitat
(35)    else
(36)        keeps the old habitat
(37) recompute HSI of each habitat
(38) associate each habitat with immigration and emigration rate
(39) if  best known solution is found  or  Num.Iteration is reached  then
(40)   terminate the algorithm