ote>, which is why we
      require i.s.L. specifically for the definition of asymptotic stability.
      Systems which are stable i.s.L. but not asymptotically stable are easy to
      construct (e.g. $\dot{x} = 0$). Interestingly, it is also possible to have
      nonlinear systems that converge (or diverge) in finite-time; a so-called
      <em>finite-time stability</em>; we will see examples of this later in the
      book, but it is a difficult topic to penetrate with graphical analysis.
      Rigorous