\begin{figure*}[ht]
    \centering
   \begin{tabular}{ccc}
  
  \begin{minipage}[b]{5.5cm}
    \centering
    \begin{equation*}
      \frac{E^n \vdash e_2 \Downarrow v_d \ n>v_d \ E^{n-v_d} \vdash e_1 \Downarrow v}{E^n \vdash\ delay\ n\ e_1\ e_2 \Downarrow  v}
    \end{equation*}\textrm{E-DELAY}
  \end{minipage} &
  \begin{minipage}[b]{5.5cm}
    \centering
    \begin{equation*}
      \frac{}{E^n \vdash\ \lambda x.e \Downarrow  cls(\lambda x.e , E^n) }
    \end{equation*}\textrm{E-LAM}
    \end{minipage}& 
    \begin{minipage}[b]{5.5cm}
    \centering
    \begin{equation*}
        \frac{ E^{n-1} \vdash e \Downarrow v_f\ E^n, x \mapsto v_f \vdash e \Downarrow v }{E^n \vdash\ feed\ x.e \Downarrow v}
    \end{equation*}\textrm{E-FEED}
    \end{minipage}
  \\
  \begin{minipage}[b]{5.5cm}
    \centering
    \begin{equation*}
      \frac{E^n \vdash e_c \Downarrow n \quad n > 0\ E^n \vdash e_t\ \Downarrow v\ }{E^n \vdash\ if (e_c)\ e_t\ else\ e_e \Downarrow v }
    \end{equation*}\textrm{E-IFTRUE}
    \end{minipage}
    &
  \begin{minipage}[b]{5.5cm}
      \centering
      \begin{equation*}
        \frac{E^n \vdash e_c \Downarrow n \quad n \leqq0\ E^n \vdash e_e\ \Downarrow v\ }{E^n \vdash\ if (e_c)\ e_t\ else\ e_e \Downarrow v }
      \end{equation*}\textrm{E-IFFALSE}
      \end{minipage}
    &
    \ 
    \\
  \multicolumn{3}{c}{
    \begin{minipage}[b]{15cm}
      \centering
      \begin{equation*}
        \frac{E^n \vdash e_1 \Downarrow cls(\lambda x_c.e_c, E^n_c) E^n \vdash e_2 \Downarrow v_2\ E^n_c,\ x_c \mapsto v_2 \vdash e_c \Downarrow v }{E^n \vdash\ e_1\ e_2 \Downarrow v }
      \end{equation*}\textrm{E-APP}
      \end{minipage}
    }
      \\

  \end{tabular}
    \caption{\label{fig:semantics}{\it Excerpt of the big-step semantics of $\lambda_{mmm}$.}}
  \end{figure*}