YES
Input TRS:
AC symbols: plus
      1: f(plus(a(),a())) -> plus(f(a()),f(a()))
      2: plus(f(a()),f(a())) -> plus(a(),f(f(a())))
Number of strict rules: 2
Direct POLO(bPol) ... removes: 1
      a 	w: 0
      f 	w: 2 * x1
      plus	w: x1 + x2 + 1
Number of strict rules: 1
Direct POLO(bPol) ... failed.
Uncurrying ... failed.
Dependency Pairs:
     #1: #plus(f(a()),f(a())) -> #plus(a(),f(f(a())))
     #2: #plus(x,plus(y,z)) ->= #plus(plus(x,y),z)
     #3: #plus(x,plus(y,z)) ->= #plus(x,y)
Number of SCCs: 1, DPs: 3
  SCC { #1..3 }
POLO(Sum)... succeeded.
      a 	w: 1
      #plus	w: x1 + x2
      f 	w: 2
      plus	w: x1 + x2 + 1
    USABLE RULES: { 2 3 }
    Removed DPs: #1 #3
Number of SCCs: 1, DPs: 1
  SCC { #2 }
only weak rules.
Number of SCCs: 0, DPs: 0
Next Dependency Pairs:
     #4: #plus(plus(f(a()),f(a())),_1) -> #plus(plus(a(),f(f(a()))),_1)
     #5: #plus(x,plus(y,z)) ->= #plus(plus(x,y),z)
     #6: #plus(x,plus(y,z)) ->= #plus(x,y)
Number of SCCs: 1, DPs: 3
  SCC { #4..6 }
POLO(Sum)... succeeded.
      a 	w: 1
      #plus	w: x1 + x2
      f 	w: 2
      plus	w: x1 + x2 + 21239
    USABLE RULES: { 2 3 }
    Removed DPs: #4 #6
Number of SCCs: 1, DPs: 1
  SCC { #5 }
only weak rules.
Number of SCCs: 0, DPs: 0