f

            =   !a!_2 f

            =   !Y!_&lt;(x) y &gt; f

            =   !Y!&lt;(x) y  =&gt; f&gt;

            =   &lt;f likes (x) y &gt;

   L_10 f   =   L_&lt; x (y)&gt; f

            =   !a!_4 f

            =   !Y!_&lt; x (y)&gt; f

            =   !Y!&lt; x (y) =&gt; f&gt;

            =   &lt;f likes  x (y)&gt;

   L_11 f   =   L_&lt; x  y &gt; f

            =   !a!_8 f

            =   !Y!_&lt; x  y &gt; f

            =   !Y!&lt; x  y =&gt; f&gt;

            =   &lt;f likes  x  y &gt;

