A Discrete Group Search Optimizer for Hybrid Flowshop Scheduling Problem with Random Breakdown

Algorithm 2

The procedure of improved variable neighborhood search.

(a) the insert local search

 𝑖𝑚𝑝𝑟𝑜𝑣𝑒=1;

 while (𝑖𝑚𝑝𝑟𝑜𝑣𝑒=1)

 do {

    𝑖𝑚𝑝𝑟𝑜𝑣𝑒=0;

   for (𝑖=1∶𝑛)

    remove job  𝑗  at random from producer

     𝜋^′ = best permutation obtained by inserting

 job 𝑗 in any possible positions of producer

     if (𝐶_max(𝜋^′) < 𝐶_max(producer))

      producer = 𝜋^′;

      𝑖𝑚𝑝𝑟𝑜𝑣𝑒=1;

     endif

  endfor

 }

(b) the swap local search

 𝑖𝑚𝑝𝑟𝑜𝑣𝑒=1;

 while (𝑖𝑚𝑝𝑟𝑜𝑣𝑒=1)

 do {

    𝑖𝑚𝑝𝑟𝑜𝑣𝑒=0;

    for (𝑖=1∶𝑛)

       𝜋^′ = best permutation obtained by swapping

 job 𝑗  with other jobs of producer

     if (𝐶_max(𝜋^′) < 𝐶_max(producer))

      producer = 𝜋^′;

      𝑖𝑚𝑝𝑟𝑜𝑣𝑒=1;

     endif

  endfor

 }