* Step 1: Sum WORST_CASE(Omega(n^1),?)
    + Considered Problem:
        - Strict TRS:
            a__c() -> a()
            a__c() -> b()
            a__c() -> c()
            a__f(X1,X2,X3) -> f(X1,X2,X3)
            a__f(a(),b(),X) -> a__f(X,X,mark(X))
            mark(a()) -> a()
            mark(b()) -> b()
            mark(c()) -> a__c()
            mark(f(X1,X2,X3)) -> a__f(X1,X2,mark(X3))
        - Signature:
            {a__c/0,a__f/3,mark/1} / {a/0,b/0,c/0,f/3}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {a__c,a__f,mark} and constructors {a,b,c,f}
    + Applied Processor:
        Sum {left = someStrategy, right = someStrategy}
    + Details:
        ()
* Step 2: DecreasingLoops WORST_CASE(Omega(n^1),?)
    + Considered Problem:
        - Strict TRS:
            a__c() -> a()
            a__c() -> b()
            a__c() -> c()
            a__f(X1,X2,X3) -> f(X1,X2,X3)
            a__f(a(),b(),X) -> a__f(X,X,mark(X))
            mark(a()) -> a()
            mark(b()) -> b()
            mark(c()) -> a__c()
            mark(f(X1,X2,X3)) -> a__f(X1,X2,mark(X3))
        - Signature:
            {a__c/0,a__f/3,mark/1} / {a/0,b/0,c/0,f/3}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {a__c,a__f,mark} and constructors {a,b,c,f}
    + Applied Processor:
        DecreasingLoops {bound = AnyLoop, narrow = 10}
    + Details:
        The system has following decreasing Loops:
          mark(z){z -> f(x,y,z)} =
            mark(f(x,y,z)) ->^+ a__f(x,y,mark(z))
              = C[mark(z) = mark(z){}]

WORST_CASE(Omega(n^1),?)