MAYBE
* Step 1: DependencyPairs MAYBE
    + Considered Problem:
        - Strict TRS:
            empty(cons(x,l)) -> false()
            empty(nil()) -> true()
            head(cons(x,l)) -> x
            if(false(),x,l) -> last(head(l),tail(l))
            if(true(),x,l) -> x
            last(x,l) -> if(empty(l),x,l)
            rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
            rev(nil()) -> nil()
            rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
            rev2(x,nil()) -> nil()
            tail(cons(x,l)) -> l
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1} / {cons/2,false/0,nil/0,rev1/2,true/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty,head,if,last,rev,rev2,tail} and constructors {cons
            ,false,nil,rev1,true}
    + Applied Processor:
        DependencyPairs {dpKind_ = DT}
    + Details:
        We add the following dependency tuples:
        
        Strict DPs
          empty#(cons(x,l)) -> c_1()
          empty#(nil()) -> c_2()
          head#(cons(x,l)) -> c_3()
          if#(false(),x,l) -> c_4(last#(head(l),tail(l)),head#(l),tail#(l))
          if#(true(),x,l) -> c_5()
          last#(x,l) -> c_6(if#(empty(l),x,l),empty#(l))
          rev#(cons(x,l)) -> c_7(rev2#(x,l))
          rev#(nil()) -> c_8()
          rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
          rev2#(x,nil()) -> c_10()
          tail#(cons(x,l)) -> c_11()
          tail#(nil()) -> c_12()
        Weak DPs
          
        
        and mark the set of starting terms.
* Step 2: UsableRules MAYBE
    + Considered Problem:
        - Strict DPs:
            empty#(cons(x,l)) -> c_1()
            empty#(nil()) -> c_2()
            head#(cons(x,l)) -> c_3()
            if#(false(),x,l) -> c_4(last#(head(l),tail(l)),head#(l),tail#(l))
            if#(true(),x,l) -> c_5()
            last#(x,l) -> c_6(if#(empty(l),x,l),empty#(l))
            rev#(cons(x,l)) -> c_7(rev2#(x,l))
            rev#(nil()) -> c_8()
            rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
            rev2#(x,nil()) -> c_10()
            tail#(cons(x,l)) -> c_11()
            tail#(nil()) -> c_12()
        - Weak TRS:
            empty(cons(x,l)) -> false()
            empty(nil()) -> true()
            head(cons(x,l)) -> x
            if(false(),x,l) -> last(head(l),tail(l))
            if(true(),x,l) -> x
            last(x,l) -> if(empty(l),x,l)
            rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
            rev(nil()) -> nil()
            rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
            rev2(x,nil()) -> nil()
            tail(cons(x,l)) -> l
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
            ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/3,c_5/0,c_6/2,c_7/1,c_8/0,c_9/2,c_10/0
            ,c_11/0,c_12/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
            ,tail#} and constructors {cons,false,nil,rev1,true}
    + Applied Processor:
        UsableRules
    + Details:
        We replace rewrite rules by usable rules:
          empty(cons(x,l)) -> false()
          empty(nil()) -> true()
          head(cons(x,l)) -> x
          rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
          rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
          rev2(x,nil()) -> nil()
          tail(cons(x,l)) -> l
          tail(nil()) -> nil()
          empty#(cons(x,l)) -> c_1()
          empty#(nil()) -> c_2()
          head#(cons(x,l)) -> c_3()
          if#(false(),x,l) -> c_4(last#(head(l),tail(l)),head#(l),tail#(l))
          if#(true(),x,l) -> c_5()
          last#(x,l) -> c_6(if#(empty(l),x,l),empty#(l))
          rev#(cons(x,l)) -> c_7(rev2#(x,l))
          rev#(nil()) -> c_8()
          rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
          rev2#(x,nil()) -> c_10()
          tail#(cons(x,l)) -> c_11()
          tail#(nil()) -> c_12()
* Step 3: PredecessorEstimation MAYBE
    + Considered Problem:
        - Strict DPs:
            empty#(cons(x,l)) -> c_1()
            empty#(nil()) -> c_2()
            head#(cons(x,l)) -> c_3()
            if#(false(),x,l) -> c_4(last#(head(l),tail(l)),head#(l),tail#(l))
            if#(true(),x,l) -> c_5()
            last#(x,l) -> c_6(if#(empty(l),x,l),empty#(l))
            rev#(cons(x,l)) -> c_7(rev2#(x,l))
            rev#(nil()) -> c_8()
            rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
            rev2#(x,nil()) -> c_10()
            tail#(cons(x,l)) -> c_11()
            tail#(nil()) -> c_12()
        - Weak TRS:
            empty(cons(x,l)) -> false()
            empty(nil()) -> true()
            head(cons(x,l)) -> x
            rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
            rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
            rev2(x,nil()) -> nil()
            tail(cons(x,l)) -> l
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
            ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/3,c_5/0,c_6/2,c_7/1,c_8/0,c_9/2,c_10/0
            ,c_11/0,c_12/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
            ,tail#} and constructors {cons,false,nil,rev1,true}
    + Applied Processor:
        PredecessorEstimation {onSelection = all simple predecessor estimation selector}
    + Details:
        We estimate the number of application of
          {1,2,3,5,8,10,11,12}
        by application of
          Pre({1,2,3,5,8,10,11,12}) = {4,6,7,9}.
        Here rules are labelled as follows:
          1: empty#(cons(x,l)) -> c_1()
          2: empty#(nil()) -> c_2()
          3: head#(cons(x,l)) -> c_3()
          4: if#(false(),x,l) -> c_4(last#(head(l),tail(l)),head#(l),tail#(l))
          5: if#(true(),x,l) -> c_5()
          6: last#(x,l) -> c_6(if#(empty(l),x,l),empty#(l))
          7: rev#(cons(x,l)) -> c_7(rev2#(x,l))
          8: rev#(nil()) -> c_8()
          9: rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
          10: rev2#(x,nil()) -> c_10()
          11: tail#(cons(x,l)) -> c_11()
          12: tail#(nil()) -> c_12()
* Step 4: RemoveWeakSuffixes MAYBE
    + Considered Problem:
        - Strict DPs:
            if#(false(),x,l) -> c_4(last#(head(l),tail(l)),head#(l),tail#(l))
            last#(x,l) -> c_6(if#(empty(l),x,l),empty#(l))
            rev#(cons(x,l)) -> c_7(rev2#(x,l))
            rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
        - Weak DPs:
            empty#(cons(x,l)) -> c_1()
            empty#(nil()) -> c_2()
            head#(cons(x,l)) -> c_3()
            if#(true(),x,l) -> c_5()
            rev#(nil()) -> c_8()
            rev2#(x,nil()) -> c_10()
            tail#(cons(x,l)) -> c_11()
            tail#(nil()) -> c_12()
        - Weak TRS:
            empty(cons(x,l)) -> false()
            empty(nil()) -> true()
            head(cons(x,l)) -> x
            rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
            rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
            rev2(x,nil()) -> nil()
            tail(cons(x,l)) -> l
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
            ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/3,c_5/0,c_6/2,c_7/1,c_8/0,c_9/2,c_10/0
            ,c_11/0,c_12/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
            ,tail#} and constructors {cons,false,nil,rev1,true}
    + Applied Processor:
        RemoveWeakSuffixes
    + Details:
        Consider the dependency graph
          1:S:if#(false(),x,l) -> c_4(last#(head(l),tail(l)),head#(l),tail#(l))
             -->_1 last#(x,l) -> c_6(if#(empty(l),x,l),empty#(l)):2
             -->_3 tail#(nil()) -> c_12():12
             -->_3 tail#(cons(x,l)) -> c_11():11
             -->_2 head#(cons(x,l)) -> c_3():7
          
          2:S:last#(x,l) -> c_6(if#(empty(l),x,l),empty#(l))
             -->_1 if#(true(),x,l) -> c_5():8
             -->_2 empty#(nil()) -> c_2():6
             -->_2 empty#(cons(x,l)) -> c_1():5
             -->_1 if#(false(),x,l) -> c_4(last#(head(l),tail(l)),head#(l),tail#(l)):1
          
          3:S:rev#(cons(x,l)) -> c_7(rev2#(x,l))
             -->_1 rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l)):4
             -->_1 rev2#(x,nil()) -> c_10():10
          
          4:S:rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
             -->_2 rev2#(x,nil()) -> c_10():10
             -->_2 rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l)):4
             -->_1 rev#(cons(x,l)) -> c_7(rev2#(x,l)):3
          
          5:W:empty#(cons(x,l)) -> c_1()
             
          
          6:W:empty#(nil()) -> c_2()
             
          
          7:W:head#(cons(x,l)) -> c_3()
             
          
          8:W:if#(true(),x,l) -> c_5()
             
          
          9:W:rev#(nil()) -> c_8()
             
          
          10:W:rev2#(x,nil()) -> c_10()
             
          
          11:W:tail#(cons(x,l)) -> c_11()
             
          
          12: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.
          9: rev#(nil()) -> c_8()
          10: rev2#(x,nil()) -> c_10()
          7: head#(cons(x,l)) -> c_3()
          11: tail#(cons(x,l)) -> c_11()
          12: tail#(nil()) -> c_12()
          5: empty#(cons(x,l)) -> c_1()
          6: empty#(nil()) -> c_2()
          8: if#(true(),x,l) -> c_5()
* Step 5: SimplifyRHS MAYBE
    + Considered Problem:
        - Strict DPs:
            if#(false(),x,l) -> c_4(last#(head(l),tail(l)),head#(l),tail#(l))
            last#(x,l) -> c_6(if#(empty(l),x,l),empty#(l))
            rev#(cons(x,l)) -> c_7(rev2#(x,l))
            rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
        - Weak TRS:
            empty(cons(x,l)) -> false()
            empty(nil()) -> true()
            head(cons(x,l)) -> x
            rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
            rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
            rev2(x,nil()) -> nil()
            tail(cons(x,l)) -> l
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
            ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/3,c_5/0,c_6/2,c_7/1,c_8/0,c_9/2,c_10/0
            ,c_11/0,c_12/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
            ,tail#} and constructors {cons,false,nil,rev1,true}
    + Applied Processor:
        SimplifyRHS
    + Details:
        Consider the dependency graph
          1:S:if#(false(),x,l) -> c_4(last#(head(l),tail(l)),head#(l),tail#(l))
             -->_1 last#(x,l) -> c_6(if#(empty(l),x,l),empty#(l)):2
          
          2:S:last#(x,l) -> c_6(if#(empty(l),x,l),empty#(l))
             -->_1 if#(false(),x,l) -> c_4(last#(head(l),tail(l)),head#(l),tail#(l)):1
          
          3:S:rev#(cons(x,l)) -> c_7(rev2#(x,l))
             -->_1 rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l)):4
          
          4:S:rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
             -->_2 rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l)):4
             -->_1 rev#(cons(x,l)) -> c_7(rev2#(x,l)):3
          
        Due to missing edges in the depndency graph, the right-hand sides of following rules could be simplified:
          if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
          last#(x,l) -> c_6(if#(empty(l),x,l))
* Step 6: Decompose MAYBE
    + Considered Problem:
        - Strict DPs:
            if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
            last#(x,l) -> c_6(if#(empty(l),x,l))
            rev#(cons(x,l)) -> c_7(rev2#(x,l))
            rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
        - Weak TRS:
            empty(cons(x,l)) -> false()
            empty(nil()) -> true()
            head(cons(x,l)) -> x
            rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
            rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
            rev2(x,nil()) -> nil()
            tail(cons(x,l)) -> l
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
            ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0,c_6/1,c_7/1,c_8/0,c_9/2,c_10/0
            ,c_11/0,c_12/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
            ,tail#} and constructors {cons,false,nil,rev1,true}
    + Applied Processor:
        Decompose {onSelection = all cycle independent sub-graph, withBound = RelativeAdd}
    + Details:
        We analyse the complexity of following sub-problems (R) and (S).
        Problem (S) is obtained from the input problem by shifting strict rules from (R) into the weak component.
        
        Problem (R)
          - Strict DPs:
              if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
              last#(x,l) -> c_6(if#(empty(l),x,l))
          - Weak DPs:
              rev#(cons(x,l)) -> c_7(rev2#(x,l))
              rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
          - Weak TRS:
              empty(cons(x,l)) -> false()
              empty(nil()) -> true()
              head(cons(x,l)) -> x
              rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
              rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
              rev2(x,nil()) -> nil()
              tail(cons(x,l)) -> l
              tail(nil()) -> nil()
          - Signature:
              {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
              ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0,c_6/1,c_7/1,c_8/0,c_9/2
              ,c_10/0,c_11/0,c_12/0}
          - Obligation:
              innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
              ,tail#} and constructors {cons,false,nil,rev1,true}
        
        Problem (S)
          - Strict DPs:
              rev#(cons(x,l)) -> c_7(rev2#(x,l))
              rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
          - Weak DPs:
              if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
              last#(x,l) -> c_6(if#(empty(l),x,l))
          - Weak TRS:
              empty(cons(x,l)) -> false()
              empty(nil()) -> true()
              head(cons(x,l)) -> x
              rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
              rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
              rev2(x,nil()) -> nil()
              tail(cons(x,l)) -> l
              tail(nil()) -> nil()
          - Signature:
              {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
              ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0,c_6/1,c_7/1,c_8/0,c_9/2
              ,c_10/0,c_11/0,c_12/0}
          - Obligation:
              innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
              ,tail#} and constructors {cons,false,nil,rev1,true}
** Step 6.a:1: RemoveWeakSuffixes MAYBE
    + Considered Problem:
        - Strict DPs:
            if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
            last#(x,l) -> c_6(if#(empty(l),x,l))
        - Weak DPs:
            rev#(cons(x,l)) -> c_7(rev2#(x,l))
            rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
        - Weak TRS:
            empty(cons(x,l)) -> false()
            empty(nil()) -> true()
            head(cons(x,l)) -> x
            rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
            rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
            rev2(x,nil()) -> nil()
            tail(cons(x,l)) -> l
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
            ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0,c_6/1,c_7/1,c_8/0,c_9/2,c_10/0
            ,c_11/0,c_12/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
            ,tail#} and constructors {cons,false,nil,rev1,true}
    + Applied Processor:
        RemoveWeakSuffixes
    + Details:
        Consider the dependency graph
          1:S:if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
             -->_1 last#(x,l) -> c_6(if#(empty(l),x,l)):2
          
          2:S:last#(x,l) -> c_6(if#(empty(l),x,l))
             -->_1 if#(false(),x,l) -> c_4(last#(head(l),tail(l))):1
          
          3:W:rev#(cons(x,l)) -> c_7(rev2#(x,l))
             -->_1 rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l)):4
          
          4:W:rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
             -->_1 rev#(cons(x,l)) -> c_7(rev2#(x,l)):3
             -->_2 rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l)):4
          
        The following weak DPs constitute a sub-graph of the DG that is closed under successors. The DPs are removed.
          3: rev#(cons(x,l)) -> c_7(rev2#(x,l))
          4: rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
** Step 6.a:2: UsableRules MAYBE
    + Considered Problem:
        - Strict DPs:
            if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
            last#(x,l) -> c_6(if#(empty(l),x,l))
        - Weak TRS:
            empty(cons(x,l)) -> false()
            empty(nil()) -> true()
            head(cons(x,l)) -> x
            rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
            rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
            rev2(x,nil()) -> nil()
            tail(cons(x,l)) -> l
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
            ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0,c_6/1,c_7/1,c_8/0,c_9/2,c_10/0
            ,c_11/0,c_12/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
            ,tail#} and constructors {cons,false,nil,rev1,true}
    + Applied Processor:
        UsableRules
    + Details:
        We replace rewrite rules by usable rules:
          empty(cons(x,l)) -> false()
          empty(nil()) -> true()
          head(cons(x,l)) -> x
          tail(cons(x,l)) -> l
          tail(nil()) -> nil()
          if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
          last#(x,l) -> c_6(if#(empty(l),x,l))
** Step 6.a:3: Failure MAYBE
  + Considered Problem:
      - Strict DPs:
          if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
          last#(x,l) -> c_6(if#(empty(l),x,l))
      - Weak TRS:
          empty(cons(x,l)) -> false()
          empty(nil()) -> true()
          head(cons(x,l)) -> x
          tail(cons(x,l)) -> l
          tail(nil()) -> nil()
      - Signature:
          {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
          ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0,c_6/1,c_7/1,c_8/0,c_9/2,c_10/0
          ,c_11/0,c_12/0}
      - Obligation:
          innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
          ,tail#} and constructors {cons,false,nil,rev1,true}
  + Applied Processor:
      EmptyProcessor
  + Details:
      The problem is still open.
** Step 6.b:1: RemoveWeakSuffixes MAYBE
    + Considered Problem:
        - Strict DPs:
            rev#(cons(x,l)) -> c_7(rev2#(x,l))
            rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
        - Weak DPs:
            if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
            last#(x,l) -> c_6(if#(empty(l),x,l))
        - Weak TRS:
            empty(cons(x,l)) -> false()
            empty(nil()) -> true()
            head(cons(x,l)) -> x
            rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
            rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
            rev2(x,nil()) -> nil()
            tail(cons(x,l)) -> l
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
            ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0,c_6/1,c_7/1,c_8/0,c_9/2,c_10/0
            ,c_11/0,c_12/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
            ,tail#} and constructors {cons,false,nil,rev1,true}
    + Applied Processor:
        RemoveWeakSuffixes
    + Details:
        Consider the dependency graph
          1:S:rev#(cons(x,l)) -> c_7(rev2#(x,l))
             -->_1 rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l)):2
          
          2:S:rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
             -->_2 rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l)):2
             -->_1 rev#(cons(x,l)) -> c_7(rev2#(x,l)):1
          
          3:W:if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
             -->_1 last#(x,l) -> c_6(if#(empty(l),x,l)):4
          
          4:W:last#(x,l) -> c_6(if#(empty(l),x,l))
             -->_1 if#(false(),x,l) -> c_4(last#(head(l),tail(l))):3
          
        The following weak DPs constitute a sub-graph of the DG that is closed under successors. The DPs are removed.
          3: if#(false(),x,l) -> c_4(last#(head(l),tail(l)))
          4: last#(x,l) -> c_6(if#(empty(l),x,l))
** Step 6.b:2: UsableRules MAYBE
    + Considered Problem:
        - Strict DPs:
            rev#(cons(x,l)) -> c_7(rev2#(x,l))
            rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
        - Weak TRS:
            empty(cons(x,l)) -> false()
            empty(nil()) -> true()
            head(cons(x,l)) -> x
            rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
            rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
            rev2(x,nil()) -> nil()
            tail(cons(x,l)) -> l
            tail(nil()) -> nil()
        - Signature:
            {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
            ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0,c_6/1,c_7/1,c_8/0,c_9/2,c_10/0
            ,c_11/0,c_12/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
            ,tail#} and constructors {cons,false,nil,rev1,true}
    + Applied Processor:
        UsableRules
    + Details:
        We replace rewrite rules by usable rules:
          rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
          rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
          rev2(x,nil()) -> nil()
          rev#(cons(x,l)) -> c_7(rev2#(x,l))
          rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
** Step 6.b:3: Failure MAYBE
  + Considered Problem:
      - Strict DPs:
          rev#(cons(x,l)) -> c_7(rev2#(x,l))
          rev2#(x,cons(y,l)) -> c_9(rev#(cons(x,rev2(y,l))),rev2#(y,l))
      - Weak TRS:
          rev(cons(x,l)) -> cons(rev1(x,l),rev2(x,l))
          rev2(x,cons(y,l)) -> rev(cons(x,rev2(y,l)))
          rev2(x,nil()) -> nil()
      - Signature:
          {empty/1,head/1,if/3,last/2,rev/1,rev2/2,tail/1,empty#/1,head#/1,if#/3,last#/2,rev#/1,rev2#/2
          ,tail#/1} / {cons/2,false/0,nil/0,rev1/2,true/0,c_1/0,c_2/0,c_3/0,c_4/1,c_5/0,c_6/1,c_7/1,c_8/0,c_9/2,c_10/0
          ,c_11/0,c_12/0}
      - Obligation:
          innermost runtime complexity wrt. defined symbols {empty#,head#,if#,last#,rev#,rev2#
          ,tail#} and constructors {cons,false,nil,rev1,true}
  + Applied Processor:
      EmptyProcessor
  + Details:
      The problem is still open.
MAYBE