WORST_CASE(?,O(n^1))
* Step 1: NaturalPI WORST_CASE(?,O(n^1))
    + Considered Problem:
        - Strict TRS:
            mem(x,nil()) -> false()
            mem(x,set(y)) -> =(x,y)
            mem(x,union(y,z)) -> or(mem(x,y),mem(x,z))
            or(x,true()) -> true()
            or(false(),false()) -> false()
            or(true(),y) -> true()
        - Signature:
            {mem/2,or/2} / {=/2,false/0,nil/0,set/1,true/0,union/2}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {mem,or} and constructors {=,false,nil,set,true,union}
    + Applied Processor:
        NaturalPI {shape = StronglyLinear, restrict = NoRestrict, uargs = UArgs, urules = URules, selector = Nothing}
    + Details:
        We apply a polynomial interpretation of kind constructor-based(stronglyLinear):
        The following argument positions are considered usable:
          uargs(or) = {1,2}
        
        Following symbols are considered usable:
          {mem,or}
        TcT has computed the following interpretation:
              p(=) = 1          
          p(false) = 0          
            p(mem) = x2         
            p(nil) = 8          
             p(or) = 2 + x1 + x2
            p(set) = 6 + x1     
           p(true) = 2          
          p(union) = 8 + x1 + x2
        
        Following rules are strictly oriented:
               mem(x,nil()) = 8                    
                            > 0                    
                            = false()              
        
              mem(x,set(y)) = 6 + y                
                            > 1                    
                            = =(x,y)               
        
          mem(x,union(y,z)) = 8 + y + z            
                            > 2 + y + z            
                            = or(mem(x,y),mem(x,z))
        
               or(x,true()) = 4 + x                
                            > 2                    
                            = true()               
        
        or(false(),false()) = 2                    
                            > 0                    
                            = false()              
        
               or(true(),y) = 4 + y                
                            > 2                    
                            = true()               
        
        
        Following rules are (at-least) weakly oriented:
        

WORST_CASE(?,O(n^1))