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Prolog program for solving the blocks problem using hill climbing

Posted By: Milind Mishra     Category: Artificial Intelligence     Views: 10092

Prolog program for solving the blocks problem using hill climbing.

Code for Prolog program for solving the blocks problem using hill climbing in Artificial Intelligence

/******************************************************************************Write a prolog program for solving the blocks problem using hill climbing *******************************************************************************/
%trace
domains
    heuristic_val = integer    
    top_type = top(integer)
    node_type = on(integer,integer)
    
    nodetype_list = node_type*
    top_list = top_type*
    file = xoutput    
database
    curr_db_list(nodetype_list,top_list,heuristic_val)
    child_db_list(nodetype_list,top_list,heuristic_val)
    best_child(nodetype_list,top_list,heuristic_val)

    db_on(integer,integer)
    db_top(integer)

    heuristic_value_db(integer)
    temp_nodelist(nodetype_list)
    temp_toplist(top_list)


predicates
    block(integer)
    initial_state
    retract_all_db
    write_list
    writelist(nodetype_list)

    get_heuristic_value(integer)
    compute_heuristic

    create_node_top_list(nodetype_list,top_list)
    create_node_list
    create_top_list
    append_node(nodetype_list,nodetype_list,nodetype_list)
    append_top(top_list,top_list,top_list)

    find_children(nodetype_list,top_list,integer)
    find_path
    find_best_child
    move_block(integer,nodetype_list,top_list)
    
    copy_on_top_to_db(nodetype_list,top_list)
    copy_on_to_db(nodetype_list)
    copy_top_to_db(top_list)
    
    delete_curr_best_db
clauses

    write_list:-
        curr_db_list(NodeList,TopList,HVal),
        writelist(NodeList),
        nl,
        nl,
        fail.
    
    writelist([]):- nl.
    writelist([Head|Tail]):-
        write(Head),
        writelist(Tail).
        
    retract_all_db:-
            retractall(curr_db_list(_,_,_)),
            retractall(db_on(_,_)),
            retractall(db_top(_)),
            retractall(heuristic_value_db(_)),
            retractall(temp_nodelist(_)),
            retractall(temp_toplist(_)),
            retractall(child_db_list(_,_,_)),
            retractall(best_child(_,_,_)).

    block(1).
    block(2).
    block(3).
    block(4).
    block(5).
    block(6).
    block(7).
    block(8).
    block(0).
    
    initial_state:- 
            assert(db_on(1,8)),
            assert(db_on(8,7)),
            assert(db_on(7,6)),
            assert(db_on(6,5)),
            assert(db_on(5,4)),
            assert(db_on(4,3)),
            assert(db_on(3,2)),
            assert(db_on(2,0)),
            assert(db_top(1)),
            create_node_top_list(NodeList,TopList),
            get_heuristic_value(HeuristicVal),
            assert(curr_db_list(NodeList,TopList,HeuristicVal)),
            writelist(NodeList).

    delete_curr_best_db:-
        retractall(best_child(_,_,_)),
        assert(best_child([],[],-9999)),
        retract(curr_db_list(_,_,_)),
        !.    
        
    find_path:-
            curr_db_list(NodeList,TopList,HeuristicVal),
%            retract(curr_db_list(NodeList,TopList,HeuristicVal)),
            delete_curr_best_db,
            find_children(NodeList,TopList,HeuristicVal),
            find_best_child,
            best_child(BestNodeList,BestTopList,BestHVal),
            writelist(BestNodeList),
            BestHVal <> 8,
            assert(curr_db_list(BestNodeList,BestTopList,BestHVal)),
%            write("BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB\n"),
            find_path.

    
    find_path:-!.

    find_children(NodeList,TopList,HeuristicVal):-
            retractall(db_top(_)),
            retractall(db_on(_,_)),
            retractall(child_db_list(_,_,_)),
            copy_on_top_to_db(NodeList,TopList),
            db_top(X),
            move_block(X,NodeList,TopList),
            fail.
    
    find_children(NodeList,TopList,HeuristicVal):-!.

    find_best_child:-
            child_db_list(NodeList,TopList,HeuristicValue),
%            write("-----CHILD-----------\n"),
%            writelist(NodeList),
            best_child(A,B,BestValue),
            HeuristicValue >= BestValue,
            not(best_child(NodeList,TopList,HeuristicValue)),
            retract(best_child(A,B,BestValue)),
            assert(best_child(NodeList,TopList,HeuristicValue)),
            fail.
            
    find_best_child:-!.

    get_heuristic_value(X):-
        assert(heuristic_value_db(0)),
        compute_heuristic(),
        heuristic_value_db(X),
        retract(heuristic_value_db(X)).
%        write(X,"\n").
        
    compute_heuristic:-
        block(Y),        
        db_on(Y,Z),
        Y = Z + 1, 
        heuristic_value_db(OLD_VAL),
        retract(heuristic_value_db(OLD_VAL)),
        NEW_VAL = OLD_VAL + 1,
        assert(heuristic_value_db(NEW_VAL)),
        fail.
    
    compute_heuristic:-
        block(Y),
        db_on(Y,Z),
        Y > Z + 1,
        heuristic_value_db(OLD_VAL),
        retract(heuristic_value_db(OLD_VAL)),
        NEW_VAL = OLD_VAL - 1,
        assert(heuristic_value_db(NEW_VAL)),
        fail.
        
        
    compute_heuristic:-
        block(Y),        
        db_on(Y,Z),
        Y < Z, 
        heuristic_value_db(OLD_VAL),
        retract(heuristic_value_db(OLD_VAL)),
        NEW_VAL = OLD_VAL - 1,
        assert(heuristic_value_db(NEW_VAL)),
        fail.
    
    compute_heuristic.

        
    move_block(X,OldNodeList,OldTopList):-
            block(Y),
            X <> Y,
            Y <> 0,
            retractall(db_on(_,_)),
            retractall(db_top(_)),
            copy_on_top_to_db(OldNodeList,OldTopList),
            db_top(Y),
            db_on(X,Z),
            Z <> 0,
            retract(db_on(X,Z)),
            retract(db_top(Y)),    
            assert(db_on(X,Y)),
            assert(db_top(Z)),
            get_heuristic_value(HeuristicValue),
            create_node_top_list(NodeList,TopList),
            not(child_db_list(NodeList,TopList,HeuristicValue)),
            assert(child_db_list(NodeList,TopList,HeuristicValue)),
%            write("MOVED--------------\n"),
%            writelist(NodeList),
            fail.

    move_block(X,OldNodeList,OldTopList):-
            block(Y),
            X <> Y,
            Y <> 0,
            retractall(db_on(_,_)),
            retractall(db_top(_)),
            copy_on_top_to_db(OldNodeList,OldTopList),
            db_top(Y),
            db_on(X,Z),
            Z = 0,
            retract(db_on(X,Z)),
            retract(db_top(Y)),    
            assert(db_on(X,Y)),
            get_heuristic_value(HeuristicValue),
            create_node_top_list(NodeList,TopList),
            not(child_db_list(NodeList,TopList,HeuristicValue)),
            assert(child_db_list(NodeList,TopList,HeuristicValue)),
%            write("MOVED--------------\n"),
%            writelist(NodeList),
            fail.

    move_block(X,OldNodeList,OldTopList):-
%            write("\nEntering YYYY"),
            block(Y),
            X <> Y,
            Y = 0,
            retractall(db_on(_,_)),
            retractall(db_top(_)),
            copy_on_top_to_db(OldNodeList,OldTopList),
            not(db_on(X,Y)),
            db_on(X,Z),
            Z <> 0,
            retract(db_on(X,Z)),
            assert(db_on(X,Y)),
            assert(db_top(Z)),
            get_heuristic_value(HeuristicValue),
            create_node_top_list(NodeList,TopList),
            not(child_db_list(NodeList,TopList,HeuristicValue)),
            assert(child_db_list(NodeList,TopList,HeuristicValue)),
%            write("MOVED--------------\n"),
%            writelist(NodeList),
            fail.
            
    move_block(X,OldNodeList,OldTopList).

    create_node_top_list(NodeList,TopList):-
            retractall(temp_nodelist(_)),
            retractall(temp_toplist(_)),
            assert(temp_nodelist([])),
            assert(temp_toplist([])),
            create_node_list,
            create_top_list,
            temp_nodelist(NodeList),
            temp_toplist(TopList),
            retractall(temp_nodelist(_)),
            retractall(temp_toplist(_)).
            
    create_top_list:-
            db_top(X),
            temp_toplist(TopList),
            retract(temp_toplist(TopList)),
            append_top([top(X)],TopList,TopList1),
            assert(temp_toplist(TopList1)),
            fail.
            
    create_top_list.
                    
    create_node_list:-
            db_on(X,Y),
            temp_nodelist(NodeList),
            retract(temp_nodelist(NodeList)),
            append_node([on(X,Y)],NodeList,NodeList1),
            assert(temp_nodelist(NodeList1)),
            fail.

    create_node_list.
    
    append_node([],ListB,ListB).
    
    append_node([X|List1],List2,[X|List3]):-
            append_node(List1,List2,List3).

    append_top([],ListB,ListB).
    
    append_top([X|List1],List2,[X|List3]):-
            append_top(List1,List2,List3).

    copy_on_top_to_db(NodeList,TopList):-
        retractall(db_on(_,_)),
        retractall(db_top(_)),
        copy_on_to_db(NodeList),
        copy_top_to_db(TopList),
        !.
    
    copy_on_to_db([]).
    copy_on_to_db([on(X,Y)|Tail]):-
        assert(db_on(X,Y)),
        copy_on_to_db(Tail).

    copy_top_to_db([]).
    copy_top_to_db([top(X)|Tail]):-
        assert(db_top(X)),
        copy_top_to_db(Tail).
goal
    clearwindow,
    retract_all_db,
    openwrite(xoutput,"hill.dat"),
    writedevice(xoutput),
    initial_state,
    find_path,
    closefile(xoutput),
    writedevice(screen).


Output

on(2,0)on(3,2)on(4,3)on(5,4)on(6,5)on(7,6)on(8,7)on(1,8)
on(1,0)on(8,7)on(7,6)on(6,5)on(5,4)on(4,3)on(3,2)on(2,0)
on(8,0)on(2,0)on(3,2)on(4,3)on(5,4)on(6,5)on(7,6)on(1,0)
on(7,0)on(1,0)on(6,5)on(5,4)on(4,3)on(3,2)on(2,0)on(8,0)
on(6,0)on(8,0)on(2,0)on(3,2)on(4,3)on(5,4)on(1,0)on(7,0)
on(5,0)on(7,0)on(1,0)on(4,3)on(3,2)on(2,0)on(8,0)on(6,0)
on(4,0)on(6,0)on(8,0)on(2,0)on(3,2)on(1,0)on(7,0)on(5,0)
on(3,0)on(5,0)on(7,0)on(1,0)on(2,0)on(8,0)on(6,0)on(4,0)
on(2,1)on(4,0)on(6,0)on(8,0)on(1,0)on(7,0)on(5,0)on(3,0)
on(3,2)on(5,0)on(7,0)on(1,0)on(8,0)on(6,0)on(4,0)on(2,1)
on(4,3)on(2,1)on(6,0)on(8,0)on(1,0)on(7,0)on(5,0)on(3,2)
on(5,4)on(3,2)on(7,0)on(1,0)on(8,0)on(6,0)on(2,1)on(4,3)
on(6,5)on(4,3)on(2,1)on(8,0)on(1,0)on(7,0)on(3,2)on(5,4)
on(7,6)on(5,4)on(3,2)on(1,0)on(8,0)on(2,1)on(4,3)on(6,5)
on(8,7)on(6,5)on(4,3)on(2,1)on(1,0)on(3,2)on(5,4)on(7,6)


  
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Milind Mishra
Milind Mishra author of Prolog program for solving the blocks problem using hill climbing is from India.
 
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