diff -r b86ff604729f -r 300bd596d696 src/Provers/Arith/combine_numerals.ML
--- a/src/Provers/Arith/combine_numerals.ML	Thu Jun 29 12:19:27 2000 +0200
+++ b/src/Provers/Arith/combine_numerals.ML	Thu Jun 29 16:50:52 2000 +0200
@@ -64,13 +64,18 @@
 
 (*the simplification procedure*)
 fun proc sg _ t =
-  let val (u,m,n,terms) = find_repeated (Termtab.empty, [], Data.dest_sum t)
+  let (*first freeze any Vars in the term to prevent flex-flex problems*)
+      val rand_s = gensym"_"
+      fun mk_inst (var as Var((a,i),T))  = 
+	    (var,  Free((a ^ rand_s ^ string_of_int i), T))
+      val t' = subst_atomic (map mk_inst (term_vars t)) t
+      val (u,m,n,terms) = find_repeated (Termtab.empty, [], Data.dest_sum t')
       val reshape =  (*Move i*u to the front and put j*u into standard form
 		       i + #m + j + k == #m + i + (j + k) *)
 	    if m=0 orelse n=0 then   (*trivial, so do nothing*)
 		raise TERM("combine_numerals", []) 
 	    else Data.prove_conv [Data.norm_tac] sg 
-			(t, 
+			(t', 
 			 Data.mk_sum ([Data.mk_coeff(m,u),
 				       Data.mk_coeff(n,u)] @ terms))
   in
@@ -78,7 +83,7 @@
 	 (Data.prove_conv 
 	    [Data.trans_tac reshape, rtac Data.left_distrib 1,
 	     Data.numeral_simp_tac] sg
-	    (t, Data.mk_sum (Data.mk_coeff(m+n,u) :: terms)))
+	    (t', Data.mk_sum (Data.mk_coeff(m+n,u) :: terms)))
   end
   handle TERM _ => None
        | TYPE _ => None;   (*Typically (if thy doesn't include Numeral)