YES

TRS:

  concat(leaf(),Y) -> Y
  concat(cons(U,V),Y) -> cons(U,concat(V,Y))
  lessleaves(X,leaf()) -> false()
  lessleaves(leaf(),cons(W,Z)) -> true()
  lessleaves(cons(U,V),cons(W,Z)) -> lessleaves(concat(U,V),concat(W,Z))

linear polynomial interpretations on N:

  concat_A(x1,x2) = x1 + x2
  concat#_A(x1,x2) = x1 + x2
  leaf_A = 1
  leaf#_A = 1
  cons_A(x1,x2) = x1 + x2 + 1
  cons#_A(x1,x2) = x1 + x2 + 1
  lessleaves_A(x1,x2) = x1 + x2
  lessleaves#_A(x1,x2) = x1 + x2
  false_A = 0
  false#_A = 0
  true_A = 0
  true#_A = 0

precedence:

  leaf > false > lessleaves > concat = cons > true