Heuristic Search for Planning with Different Forced Goal-Ordering Constraints

Algorithm 1

Ex_MsFS algorithm.

Input: planning problem (𝑂,𝐼,𝐺).

Output: plan 𝜋 with 𝐺⊆𝑟𝑒𝑠𝑢𝑙𝑡(𝐼,𝑝)

01 𝑠=𝐼, 𝐺^′=∅, 𝜋=∅;

02     do{

03     𝑄=∅, 𝐿=∅;

04     select ¬𝑔∈𝑠 with the fewest number of available GAO;

05     𝑄.push_back((𝑠,𝑔)), 𝑡𝑒𝑚_𝑠←𝑠;

06     do{

07      𝑠←𝑄.pop_back().𝑠, 𝑔←𝑄.pop_back().𝑔;

08       select an available GAO 𝑜_𝑔 with the biggest excludable GAO set;

09      𝑠^′←𝑟𝑒𝑠𝑢𝑙𝑡(𝑠,𝜋_𝑜𝑔); 𝐿.push_back((𝑠^′,𝑜,𝑠));

10       for each  ¬𝑔^′∈𝑠^′

11        if  𝑔^′ does not have available GAO in 𝑠^′

12       if Move_ahead(𝐿,𝑔^′,𝐿^′)==true;

13       𝐿.clear(), 𝐿←𝐿^′, 𝑠^′←𝐿.back().𝑠^′;

14       else

15       if  𝐺^′.contain(𝑔^′)== true

16            return FAILURE;

17      else

18       𝑄.clear(), 𝐿.clear(), 𝐺^′.insert(𝑔^′);

19       𝑄.push_back((𝑡𝑒𝑚_𝑠,𝑔^′)), go to step 05;

20       for each  ¬𝑔^′∈𝑠^′

21          if Available GAOs of 𝑔^′ in 𝑠^′ is fewer than that of in 𝑠

22         if   𝑄.contain((𝑠^′,𝑔^′))==false

23        𝑄.push_back((𝑠^′,𝑔^′));

24           }while(𝑄≠∅)

25     for  𝑖=0∶𝐿.size()-1

26    𝜋.push_back(𝐿[𝑖].𝑜);

27      𝑠←𝑠^′, 𝐿.clear();

28    }while(𝐺⊈𝑠)

29    return  𝜋.