Add Trim method

unify.tex

@@ -444,6 +444,25 @@ Their upper and lower bounds are fresh type variables.
       \end{array}
       $
     \\\\
+    \rulename{Trim}
+    & 
+    $
+    \begin{array}[c]{@{}ll}
+    \begin{array}[c]{l}
+        \wildcardEnv \vdash 
+        C \cup \, \set{ \wctype{\Delta,\Delta'}{C}{\ol{S}} \lessdot \type{T} } \\ 
+      \hline
+      \vspace*{-0.4cm}\\
+        \wildcardEnv \vdash 
+        C \cup \, \set{ \wctype{\Delta}{C}{\ol{S}} \lessdot \type{T} } \\  
+    \end{array}
+     %\quad \ol{Y} = \textit{fresh}(\ol{X})
+     \quad \begin{array}[c]{l}
+      \text{fv}(\ol{S}) \cap \Delta' = \emptyset
+      \end{array}
+    \end{array}
+    $
+  \\\\
 %         \rulename{Adopt}
 %         & $
 %         \begin{array}[c]{@{}ll}