Input TRS:
    1: is_empty(nil()) -> true()
    2: is_empty(cons(x,l)) -> false()
    3: hd(cons(x,l)) -> x
    4: tl(cons(x,l)) -> l
    5: append(l1,l2) -> ifappend(l1,l2,l1)
    6: ifappend(l1,l2,nil()) -> l2
    7: ifappend(l1,l2,cons(x,l)) -> cons(x,append(l,l2))
Number of strict rules: 7
Direct Order(PosReal,>,Poly) ... failed.
Freezing ... failed.
Dependency Pairs:
   #1: #ifappend(l1,l2,cons(x,l)) -> #append(l,l2)
   #2: #append(l1,l2) -> #ifappend(l1,l2,l1)
Number of SCCs: 1, DPs: 2, edges: 2
	SCC { #1 #2 }
Removing DPs: Order(PosReal,>,Sum)... succeeded.
    hd(x1)	weight: 0
#append(x1,x2)	weight: (/ 1 4) + x1
#is_empty(x1)	weight: 0
ifappend(x1,x2,x3)	weight: 0
 false()	weight: 0
  true()	weight: 0
  #tl(x1)	weight: 0
append(x1,x2)	weight: 0
    tl(x1)	weight: 0
   nil()	weight: 0
is_empty(x1)	weight: 0
  #hd(x1)	weight: 0
  cons(x1,x2)	weight: (/ 1 2) + x2
#ifappend(x1,x2,x3)	weight: x3
    Usable rules: { }
    Removed DPs: #1 #2
Number of SCCs: 0, DPs: 0, edges: 0
YES