MAYBE
* Step 1: DependencyPairs MAYBE
    + Considered Problem:
        - Strict TRS:
            empty(cons(n,x)) -> false()
            empty(nil()) -> true()
            head(cons(n,x)) -> n
            if(false(),b,x) -> if2(b,x)
            if(true(),b,x) -> weight_undefined_error()
            if2(false(),x) -> weight(sum(x,cons(0(),tail(tail(x)))))
            if2(true(),x) -> head(x)
            sum(cons(0(),x),y) -> sum(x,y)
            sum(cons(s(n),x),cons(m,y)) -> sum(cons(n,x),cons(s(m),y))
            sum(nil(),y) -> y
            tail(cons(n,x)) -> x
            tail(nil()) -> nil()
            weight(x) -> if(empty(x),empty(tail(x)),x)
        - Signature:
            {empty/1,head/1,if/3,if2/2,sum/2,tail/1,weight/1} / {0/0,cons/2,false/0,nil/0,s/1,true/0
            ,weight_undefined_error/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty,head,if,if2,sum,tail,weight} and constructors {0
            ,cons,false,nil,s,true,weight_undefined_error}
    + Applied Processor:
        DependencyPairs {dpKind_ = DT}
    + Details:
        We add the following dependency tuples:
        
        Strict DPs
          empty#(cons(n,x)) -> c_1()
          empty#(nil()) -> c_2()
          head#(cons(n,x)) -> c_3()
          if#(false(),b,x) -> c_4(if2#(b,x))
          if#(true(),b,x) -> c_5()
          if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                ,sum#(x,cons(0(),tail(tail(x))))
                                ,tail#(tail(x))
                                ,tail#(x))
          if2#(true(),x) -> c_7(head#(x))
          sum#(cons(0(),x),y) -> c_8(sum#(x,y))
          sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
          sum#(nil(),y) -> c_10()
          tail#(cons(n,x)) -> c_11()
          tail#(nil()) -> c_12()
          weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x))
        Weak DPs
          
        
        and mark the set of starting terms.
* Step 2: UsableRules MAYBE
    + Considered Problem:
        - Strict DPs:
            empty#(cons(n,x)) -> c_1()
            empty#(nil()) -> c_2()
            head#(cons(n,x)) -> c_3()
            if#(false(),b,x) -> c_4(if2#(b,x))
            if#(true(),b,x) -> c_5()
            if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                  ,sum#(x,cons(0(),tail(tail(x))))
                                  ,tail#(tail(x))
                                  ,tail#(x))
            if2#(true(),x) -> c_7(head#(x))
            sum#(cons(0(),x),y) -> c_8(sum#(x,y))
            sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
            sum#(nil(),y) -> c_10()
            tail#(cons(n,x)) -> c_11()
            tail#(nil()) -> c_12()
            weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x))
        - Weak TRS:
            empty(cons(n,x)) -> false()
            empty(nil()) -> true()
            head(cons(n,x)) -> n
            if(false(),b,x) -> if2(b,x)
            if(true(),b,x) -> weight_undefined_error()
            if2(false(),x) -> weight(sum(x,cons(0(),tail(tail(x)))))
            if2(true(),x) -> head(x)
            sum(cons(0(),x),y) -> sum(x,y)
            sum(cons(s(n),x),cons(m,y)) -> sum(cons(n,x),cons(s(m),y))
            sum(nil(),y) -> y
            tail(cons(n,x)) -> x
            tail(nil()) -> nil()
            weight(x) -> if(empty(x),empty(tail(x)),x)
        - Signature:
            {empty/1,head/1,if/3,if2/2,sum/2,tail/1,weight/1,empty#/1,head#/1,if#/3,if2#/2,sum#/2,tail#/1
            ,weight#/1} / {0/0,cons/2,false/0,nil/0,s/1,true/0,weight_undefined_error/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0
            ,c_6/4,c_7/1,c_8/1,c_9/1,c_10/0,c_11/0,c_12/0,c_13/4}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,if2#,sum#,tail#
            ,weight#} and constructors {0,cons,false,nil,s,true,weight_undefined_error}
    + Applied Processor:
        UsableRules
    + Details:
        We replace rewrite rules by usable rules:
          empty(cons(n,x)) -> false()
          empty(nil()) -> true()
          sum(cons(0(),x),y) -> sum(x,y)
          sum(cons(s(n),x),cons(m,y)) -> sum(cons(n,x),cons(s(m),y))
          sum(nil(),y) -> y
          tail(cons(n,x)) -> x
          tail(nil()) -> nil()
          empty#(cons(n,x)) -> c_1()
          empty#(nil()) -> c_2()
          head#(cons(n,x)) -> c_3()
          if#(false(),b,x) -> c_4(if2#(b,x))
          if#(true(),b,x) -> c_5()
          if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                ,sum#(x,cons(0(),tail(tail(x))))
                                ,tail#(tail(x))
                                ,tail#(x))
          if2#(true(),x) -> c_7(head#(x))
          sum#(cons(0(),x),y) -> c_8(sum#(x,y))
          sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
          sum#(nil(),y) -> c_10()
          tail#(cons(n,x)) -> c_11()
          tail#(nil()) -> c_12()
          weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x))
* Step 3: PredecessorEstimation MAYBE
    + Considered Problem:
        - Strict DPs:
            empty#(cons(n,x)) -> c_1()
            empty#(nil()) -> c_2()
            head#(cons(n,x)) -> c_3()
            if#(false(),b,x) -> c_4(if2#(b,x))
            if#(true(),b,x) -> c_5()
            if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                  ,sum#(x,cons(0(),tail(tail(x))))
                                  ,tail#(tail(x))
                                  ,tail#(x))
            if2#(true(),x) -> c_7(head#(x))
            sum#(cons(0(),x),y) -> c_8(sum#(x,y))
            sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
            sum#(nil(),y) -> c_10()
            tail#(cons(n,x)) -> c_11()
            tail#(nil()) -> c_12()
            weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x))
        - Weak TRS:
            empty(cons(n,x)) -> false()
            empty(nil()) -> true()
            sum(cons(0(),x),y) -> sum(x,y)
            sum(cons(s(n),x),cons(m,y)) -> sum(cons(n,x),cons(s(m),y))
            sum(nil(),y) -> y
            tail(cons(n,x)) -> x
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,if2/2,sum/2,tail/1,weight/1,empty#/1,head#/1,if#/3,if2#/2,sum#/2,tail#/1
            ,weight#/1} / {0/0,cons/2,false/0,nil/0,s/1,true/0,weight_undefined_error/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0
            ,c_6/4,c_7/1,c_8/1,c_9/1,c_10/0,c_11/0,c_12/0,c_13/4}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,if2#,sum#,tail#
            ,weight#} and constructors {0,cons,false,nil,s,true,weight_undefined_error}
    + Applied Processor:
        PredecessorEstimation {onSelection = all simple predecessor estimation selector}
    + Details:
        We estimate the number of application of
          {1,2,3,5,10,11,12}
        by application of
          Pre({1,2,3,5,10,11,12}) = {6,7,8,13}.
        Here rules are labelled as follows:
          1: empty#(cons(n,x)) -> c_1()
          2: empty#(nil()) -> c_2()
          3: head#(cons(n,x)) -> c_3()
          4: if#(false(),b,x) -> c_4(if2#(b,x))
          5: if#(true(),b,x) -> c_5()
          6: if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                   ,sum#(x,cons(0(),tail(tail(x))))
                                   ,tail#(tail(x))
                                   ,tail#(x))
          7: if2#(true(),x) -> c_7(head#(x))
          8: sum#(cons(0(),x),y) -> c_8(sum#(x,y))
          9: sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
          10: sum#(nil(),y) -> c_10()
          11: tail#(cons(n,x)) -> c_11()
          12: tail#(nil()) -> c_12()
          13: weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x))
* Step 4: PredecessorEstimation MAYBE
    + Considered Problem:
        - Strict DPs:
            if#(false(),b,x) -> c_4(if2#(b,x))
            if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                  ,sum#(x,cons(0(),tail(tail(x))))
                                  ,tail#(tail(x))
                                  ,tail#(x))
            if2#(true(),x) -> c_7(head#(x))
            sum#(cons(0(),x),y) -> c_8(sum#(x,y))
            sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
            weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x))
        - Weak DPs:
            empty#(cons(n,x)) -> c_1()
            empty#(nil()) -> c_2()
            head#(cons(n,x)) -> c_3()
            if#(true(),b,x) -> c_5()
            sum#(nil(),y) -> c_10()
            tail#(cons(n,x)) -> c_11()
            tail#(nil()) -> c_12()
        - Weak TRS:
            empty(cons(n,x)) -> false()
            empty(nil()) -> true()
            sum(cons(0(),x),y) -> sum(x,y)
            sum(cons(s(n),x),cons(m,y)) -> sum(cons(n,x),cons(s(m),y))
            sum(nil(),y) -> y
            tail(cons(n,x)) -> x
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,if2/2,sum/2,tail/1,weight/1,empty#/1,head#/1,if#/3,if2#/2,sum#/2,tail#/1
            ,weight#/1} / {0/0,cons/2,false/0,nil/0,s/1,true/0,weight_undefined_error/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0
            ,c_6/4,c_7/1,c_8/1,c_9/1,c_10/0,c_11/0,c_12/0,c_13/4}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,if2#,sum#,tail#
            ,weight#} and constructors {0,cons,false,nil,s,true,weight_undefined_error}
    + Applied Processor:
        PredecessorEstimation {onSelection = all simple predecessor estimation selector}
    + Details:
        We estimate the number of application of
          {3}
        by application of
          Pre({3}) = {1}.
        Here rules are labelled as follows:
          1: if#(false(),b,x) -> c_4(if2#(b,x))
          2: if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                   ,sum#(x,cons(0(),tail(tail(x))))
                                   ,tail#(tail(x))
                                   ,tail#(x))
          3: if2#(true(),x) -> c_7(head#(x))
          4: sum#(cons(0(),x),y) -> c_8(sum#(x,y))
          5: sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
          6: weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x))
          7: empty#(cons(n,x)) -> c_1()
          8: empty#(nil()) -> c_2()
          9: head#(cons(n,x)) -> c_3()
          10: if#(true(),b,x) -> c_5()
          11: sum#(nil(),y) -> c_10()
          12: tail#(cons(n,x)) -> c_11()
          13: tail#(nil()) -> c_12()
* Step 5: RemoveWeakSuffixes MAYBE
    + Considered Problem:
        - Strict DPs:
            if#(false(),b,x) -> c_4(if2#(b,x))
            if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                  ,sum#(x,cons(0(),tail(tail(x))))
                                  ,tail#(tail(x))
                                  ,tail#(x))
            sum#(cons(0(),x),y) -> c_8(sum#(x,y))
            sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
            weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x))
        - Weak DPs:
            empty#(cons(n,x)) -> c_1()
            empty#(nil()) -> c_2()
            head#(cons(n,x)) -> c_3()
            if#(true(),b,x) -> c_5()
            if2#(true(),x) -> c_7(head#(x))
            sum#(nil(),y) -> c_10()
            tail#(cons(n,x)) -> c_11()
            tail#(nil()) -> c_12()
        - Weak TRS:
            empty(cons(n,x)) -> false()
            empty(nil()) -> true()
            sum(cons(0(),x),y) -> sum(x,y)
            sum(cons(s(n),x),cons(m,y)) -> sum(cons(n,x),cons(s(m),y))
            sum(nil(),y) -> y
            tail(cons(n,x)) -> x
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,if2/2,sum/2,tail/1,weight/1,empty#/1,head#/1,if#/3,if2#/2,sum#/2,tail#/1
            ,weight#/1} / {0/0,cons/2,false/0,nil/0,s/1,true/0,weight_undefined_error/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0
            ,c_6/4,c_7/1,c_8/1,c_9/1,c_10/0,c_11/0,c_12/0,c_13/4}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,if2#,sum#,tail#
            ,weight#} and constructors {0,cons,false,nil,s,true,weight_undefined_error}
    + Applied Processor:
        RemoveWeakSuffixes
    + Details:
        Consider the dependency graph
          1:S:if#(false(),b,x) -> c_4(if2#(b,x))
             -->_1 if2#(true(),x) -> c_7(head#(x)):10
             -->_1 if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                         ,sum#(x,cons(0(),tail(tail(x))))
                                         ,tail#(tail(x))
                                         ,tail#(x)):2
          
          2:S:if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                    ,sum#(x,cons(0(),tail(tail(x))))
                                    ,tail#(tail(x))
                                    ,tail#(x))
             -->_1 weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x)):5
             -->_2 sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y))):4
             -->_2 sum#(cons(0(),x),y) -> c_8(sum#(x,y)):3
             -->_4 tail#(nil()) -> c_12():13
             -->_3 tail#(nil()) -> c_12():13
             -->_4 tail#(cons(n,x)) -> c_11():12
             -->_3 tail#(cons(n,x)) -> c_11():12
             -->_2 sum#(nil(),y) -> c_10():11
          
          3:S:sum#(cons(0(),x),y) -> c_8(sum#(x,y))
             -->_1 sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y))):4
             -->_1 sum#(nil(),y) -> c_10():11
             -->_1 sum#(cons(0(),x),y) -> c_8(sum#(x,y)):3
          
          4:S:sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
             -->_1 sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y))):4
             -->_1 sum#(cons(0(),x),y) -> c_8(sum#(x,y)):3
          
          5:S:weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x))
             -->_4 tail#(nil()) -> c_12():13
             -->_4 tail#(cons(n,x)) -> c_11():12
             -->_1 if#(true(),b,x) -> c_5():9
             -->_3 empty#(nil()) -> c_2():7
             -->_2 empty#(nil()) -> c_2():7
             -->_3 empty#(cons(n,x)) -> c_1():6
             -->_2 empty#(cons(n,x)) -> c_1():6
             -->_1 if#(false(),b,x) -> c_4(if2#(b,x)):1
          
          6:W:empty#(cons(n,x)) -> c_1()
             
          
          7:W:empty#(nil()) -> c_2()
             
          
          8:W:head#(cons(n,x)) -> c_3()
             
          
          9:W:if#(true(),b,x) -> c_5()
             
          
          10:W:if2#(true(),x) -> c_7(head#(x))
             -->_1 head#(cons(n,x)) -> c_3():8
          
          11:W:sum#(nil(),y) -> c_10()
             
          
          12:W:tail#(cons(n,x)) -> c_11()
             
          
          13:W:tail#(nil()) -> c_12()
             
          
        The following weak DPs constitute a sub-graph of the DG that is closed under successors. The DPs are removed.
          11: sum#(nil(),y) -> c_10()
          6: empty#(cons(n,x)) -> c_1()
          7: empty#(nil()) -> c_2()
          9: if#(true(),b,x) -> c_5()
          12: tail#(cons(n,x)) -> c_11()
          13: tail#(nil()) -> c_12()
          10: if2#(true(),x) -> c_7(head#(x))
          8: head#(cons(n,x)) -> c_3()
* Step 6: SimplifyRHS MAYBE
    + Considered Problem:
        - Strict DPs:
            if#(false(),b,x) -> c_4(if2#(b,x))
            if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                  ,sum#(x,cons(0(),tail(tail(x))))
                                  ,tail#(tail(x))
                                  ,tail#(x))
            sum#(cons(0(),x),y) -> c_8(sum#(x,y))
            sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
            weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x))
        - Weak TRS:
            empty(cons(n,x)) -> false()
            empty(nil()) -> true()
            sum(cons(0(),x),y) -> sum(x,y)
            sum(cons(s(n),x),cons(m,y)) -> sum(cons(n,x),cons(s(m),y))
            sum(nil(),y) -> y
            tail(cons(n,x)) -> x
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,if2/2,sum/2,tail/1,weight/1,empty#/1,head#/1,if#/3,if2#/2,sum#/2,tail#/1
            ,weight#/1} / {0/0,cons/2,false/0,nil/0,s/1,true/0,weight_undefined_error/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0
            ,c_6/4,c_7/1,c_8/1,c_9/1,c_10/0,c_11/0,c_12/0,c_13/4}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,if2#,sum#,tail#
            ,weight#} and constructors {0,cons,false,nil,s,true,weight_undefined_error}
    + Applied Processor:
        SimplifyRHS
    + Details:
        Consider the dependency graph
          1:S:if#(false(),b,x) -> c_4(if2#(b,x))
             -->_1 if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                         ,sum#(x,cons(0(),tail(tail(x))))
                                         ,tail#(tail(x))
                                         ,tail#(x)):2
          
          2:S:if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x)))))
                                    ,sum#(x,cons(0(),tail(tail(x))))
                                    ,tail#(tail(x))
                                    ,tail#(x))
             -->_1 weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x)):5
             -->_2 sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y))):4
             -->_2 sum#(cons(0(),x),y) -> c_8(sum#(x,y)):3
          
          3:S:sum#(cons(0(),x),y) -> c_8(sum#(x,y))
             -->_1 sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y))):4
             -->_1 sum#(cons(0(),x),y) -> c_8(sum#(x,y)):3
          
          4:S:sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
             -->_1 sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y))):4
             -->_1 sum#(cons(0(),x),y) -> c_8(sum#(x,y)):3
          
          5:S:weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x),empty#(x),empty#(tail(x)),tail#(x))
             -->_1 if#(false(),b,x) -> c_4(if2#(b,x)):1
          
        Due to missing edges in the depndency graph, the right-hand sides of following rules could be simplified:
          if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x))))),sum#(x,cons(0(),tail(tail(x)))))
          weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x))
* Step 7: Failure MAYBE
  + Considered Problem:
      - Strict DPs:
          if#(false(),b,x) -> c_4(if2#(b,x))
          if2#(false(),x) -> c_6(weight#(sum(x,cons(0(),tail(tail(x))))),sum#(x,cons(0(),tail(tail(x)))))
          sum#(cons(0(),x),y) -> c_8(sum#(x,y))
          sum#(cons(s(n),x),cons(m,y)) -> c_9(sum#(cons(n,x),cons(s(m),y)))
          weight#(x) -> c_13(if#(empty(x),empty(tail(x)),x))
      - Weak TRS:
          empty(cons(n,x)) -> false()
          empty(nil()) -> true()
          sum(cons(0(),x),y) -> sum(x,y)
          sum(cons(s(n),x),cons(m,y)) -> sum(cons(n,x),cons(s(m),y))
          sum(nil(),y) -> y
          tail(cons(n,x)) -> x
          tail(nil()) -> nil()
      - Signature:
          {empty/1,head/1,if/3,if2/2,sum/2,tail/1,weight/1,empty#/1,head#/1,if#/3,if2#/2,sum#/2,tail#/1
          ,weight#/1} / {0/0,cons/2,false/0,nil/0,s/1,true/0,weight_undefined_error/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0
          ,c_6/2,c_7/1,c_8/1,c_9/1,c_10/0,c_11/0,c_12/0,c_13/1}
      - Obligation:
          innermost runtime complexity wrt. defined symbols {empty#,head#,if#,if2#,sum#,tail#
          ,weight#} and constructors {0,cons,false,nil,s,true,weight_undefined_error}
  + Applied Processor:
      EmptyProcessor
  + Details:
      The problem is still open.
MAYBE