src/HOL/Multivariate_Analysis/normarith.ML

   val lctab = vector_lincombs (map snd (filter (not o fst) ntms))
   val (fxns, ctxt') = Variable.variant_fixes (replicate (length lctab) "x") ctxt
   fun instantiate_cterm' ty tms = Drule.cterm_rule (Drule.instantiate' ty tms)
   fun mk_norm t = Thm.capply (instantiate_cterm' [SOME (ctyp_of_term t)] [] @{cpat "norm :: (?'a :: real_normed_vector) => real"}) t
   fun mk_equals l r = Thm.capply (Thm.capply (instantiate_cterm' [SOME (ctyp_of_term l)] [] @{cpat "op == :: ?'a =>_"}) l) r
-  val asl = map2 (fn (t,_) => fn n => Thm.assume (mk_equals (mk_norm t) (cterm_of (ProofContext.theory_of ctxt') (Free(n,@{typ real}))))) lctab fxns
+  val asl = map2 (fn (t,_) => fn n => Thm.assume (mk_equals (mk_norm t) (cterm_of (Proof_Context.theory_of ctxt') (Free(n,@{typ real}))))) lctab fxns
   val replace_conv = try_conv (rewrs_conv asl)
   val replace_rule = fconv_rule (funpow 2 arg_conv (replacenegnorms replace_conv))
   val ges' =
        fold_rev (fn th => fn ths => conjunct1(norm_mp th)::ths)
               asl (map replace_rule ges)