NO
* Step 1: FromIts NO
    + Considered Problem:
        Rules:
          0. f20(A,B) -> f1(0,0)         True                                                               (1,1)
          1. f1(A,B)  -> f1(1 + A,1 + B) [A + -1*B >= 0 && B >= 0 && A + B >= 0 && -1*A + B >= 0 && A >= 0] (?,1)
        Signature:
          {(f1,2);(f20,2)}
        Flow Graph:
          [0->{1},1->{1}]
        
    + Applied Processor:
        FromIts
    + Details:
        ()
* Step 2: CloseWith NO
    + Considered Problem:
        Rules:
          f20(A,B) -> f1(0,0)          True
          f1(A,B)  -> f1(1 + A,1 + B)  [A + -1*B >= 0 && B >= 0 && A + B >= 0 && -1*A + B >= 0 && A >= 0]
        Signature:
          {(f1,2);(f20,2)}
        Rule Graph:
          [0->{1},1->{1}]
    + Applied Processor:
        CloseWith False
    + Details:
        ()

NO