--- a/src/core_env.sml	Thu Oct 30 15:39:06 2008 -0400
+++ b/src/core_env.sml	Thu Oct 30 16:58:54 2008 -0400
@@ -93,6 +93,35 @@
                 bind = fn ((xn, rep), U.Exp.RelC _) => (xn+1, liftConInCon 0 rep)
                         | (ctx, _) => ctx}
 
+val liftExpInExp =
+    U.Exp.mapB {kind = fn k => k,
+                con = fn _ => fn c => c,
+                exp = fn bound => fn e =>
+                                     case e of
+                                         ERel xn =>
+                                         if xn < bound then
+                                             e
+                                         else
+                                             ERel (xn + 1)
+                                       | _ => e,
+                bind = fn (bound, U.Exp.RelE _) => bound + 1
+                        | (bound, _) => bound}
+
+val subExpInExp =
+    U.Exp.mapB {kind = fn k => k,
+                con = fn _ => fn c => c,
+                exp = fn (xn, rep) => fn e =>
+                                  case e of
+                                      ERel xn' =>
+                                      (case Int.compare (xn', xn) of
+                                           EQUAL => #1 rep
+                                         | GREATER=> ERel (xn' - 1)
+                                         | LESS => e)
+                                    | _ => e,
+                bind = fn ((xn, rep), U.Exp.RelE _) => (xn+1, liftExpInExp 0 rep)
+                        | ((xn, rep), U.Exp.RelC _) => (xn, liftConInExp 0 rep)
+                        | (ctx, _) => ctx}
+
 (* Back to environments *)
 
 exception UnboundRel of int