YES

TRS:

  qsort(nil()) -> nil()
  qsort(.(x,y)) -> ++(qsort(lowers(x,y)),.(x,qsort(greaters(x,y))))
  lowers(x,nil()) -> nil()
  lowers(x,.(y,z)) -> if(<=(y,x),.(y,lowers(x,z)),lowers(x,z))
  greaters(x,nil()) -> nil()
  greaters(x,.(y,z)) -> if(<=(y,x),greaters(x,z),.(y,greaters(x,z)))

max/plus interpretations on N:

  qsort_A(x1) = max{10, -9 + x1}
  qsort#_A(x1) = max{22, 24 + x1}
  nil_A = 10
  nil#_A = 46
  ._A(x1,x2) = max{48, -1, -1}
  .#_A(x1,x2) = max{44, 45, 42}
  ++_A(x1,x2) = max{11, 13 + x1, 11}
  ++#_A(x1,x2) = max{43, 62 + x1, 72}
  lowers_A(x1,x2) = max{7, 19, 6}
  lowers#_A(x1,x2) = max{45, 21, 41}
  greaters_A(x1,x2) = max{19, 8, 9}
  greaters#_A(x1,x2) = max{47, 1, 49}
  if_A(x1,x2,x3) = max{19, 6, 8, 9}
  if#_A(x1,x2,x3) = max{20, 0, -8 + x2, 1 + x3}
  <=_A(x1,x2) = max{1, 1 + x1, 1 + x2}
  <=#_A(x1,x2) = max{0, 20, 0}

precedence:

  qsort > lowers = greaters > nil = . = if = <= > ++