diff --git a/src/core/term.ml b/src/core/term.ml
index cd0b0c294db457fcc40bd084053e234179c80e88..187e1c8cee32ca7a73a90064215a21a3a04d13a8 100644
--- a/src/core/term.ml
+++ b/src/core/term.ml
@@ -1896,33 +1896,32 @@ let f_map_simp fnT fnF f = f_label_copy f (match f.f_node with
 
 let f_map_simp fnT = f_map_simp (protect fnT)
 
-(** Proposition of another fold *)
-(* Type in terms and formulae *)
-let rec t_fold_ty fty s t =
-  let s = t_fold_unsafe (t_fold_ty fty) (f_fold_ty fty) s t in
-  let s = fty s t.t_ty in
+(* Fold over types in terms and formulas *)
+
+let rec t_fold_ty fty acc t =
+  let acc = t_fold_unsafe (t_fold_ty fty) (f_fold_ty fty) acc t in
+  let acc = fty acc t.t_ty in
   match t.t_node with
-    | Teps fb ->
-      let vs,_,_ = fb in
-      fty s vs.vs_ty
-    | _ -> s
+    | Teps (vs,_,_) -> fty acc vs.vs_ty
+    | _ -> acc
 
-and f_fold_ty fty s f =
-  let s = f_fold_unsafe (t_fold_ty fty) (f_fold_ty fty) s f in
+and f_fold_ty fty acc f =
+  let acc = f_fold_unsafe (t_fold_ty fty) (f_fold_ty fty) acc f in
   match f.f_node with
-    | Fquant (_,fq) ->
-      let (vsl,_,_,_) = fq in
-      List.fold_left (fun s vs -> fty s vs.vs_ty) s vsl
-    | _ -> s
+    | Fquant (_,(vsl,_,_,_)) ->
+        List.fold_left (fun acc vs -> fty acc vs.vs_ty) acc vsl
+    | _ -> acc
+
+(* Fold over EXACTLY WHAT? in terms and formulas *)
 
-let rec t_fold_sig fty s t =
-  let s = t_fold_unsafe (t_fold_sig fty) (f_fold_sig fty) s t in
+let rec t_fold_sig fty acc t =
+  let acc = t_fold_unsafe (t_fold_sig fty) (f_fold_sig fty) acc t in
   match t.t_node with
-    | Tapp (fs,tl) -> fty s fs (List.map (fun t -> t.t_ty) tl)
-    | _ -> s
+    | Tapp (fs,tl) -> fty acc fs (List.map (fun t -> t.t_ty) tl)
+    | _ -> acc
 
-and f_fold_sig fty s f =
-  let s = f_fold_unsafe (t_fold_sig fty) (f_fold_sig fty) s f in
+and f_fold_sig fty acc f =
+  let acc = f_fold_unsafe (t_fold_sig fty) (f_fold_sig fty) acc f in
   match f.f_node with
-    | Fapp (fs,tl) -> fty s fs (List.map (fun t -> t.t_ty) tl)
-    | _ -> s
+    | Fapp (fs,tl) -> fty acc fs (List.map (fun t -> t.t_ty) tl)
+    | _ -> acc
diff --git a/src/core/term.mli b/src/core/term.mli
index e070659bc23447ffd780dee0c7ecc149da3f8b83..1c903b69d906872bae5c5b0dd1a39316839d9a82 100644
--- a/src/core/term.mli
+++ b/src/core/term.mli
@@ -424,6 +424,7 @@ val list_map_cont : (('a -> 'b) -> 'c -> 'b) ->
                     ('a list -> 'b) -> 'c list -> 'b
 
 (** simplification map *)
+
 val f_map_simp : (term -> term) -> (fmla -> fmla) -> fmla -> fmla
 
 (** map/fold over free variables *)
@@ -472,6 +473,7 @@ val f_ty_freevars : Stv.t -> fmla -> Stv.t
 
 val t_equal_alpha : term -> term -> bool
 val f_equal_alpha : fmla -> fmla -> bool
+
 module Hterm_alpha : Hashtbl.S with type key = term
 module Hfmla_alpha : Hashtbl.S with type key = fmla
 
@@ -506,7 +508,8 @@ exception NoMatch
 val t_match : term Mvs.t -> term -> term -> term Mvs.t
 val f_match : term Mvs.t -> fmla -> fmla -> term Mvs.t
 
-(** Proposition of another fold *)
+(** fold over types in terms and formulas *)
+
 val t_fold_ty : ('a -> ty -> 'a) -> 'a -> term -> 'a
 val f_fold_ty : ('a -> ty -> 'a) -> 'a -> fmla -> 'a
 
diff --git a/src/core/ty.mli b/src/core/ty.mli
index e14560961252c5b602c2611f2ffa07812321e853..8088b6c68ffb6420b6e96e982c56e8dab9a40572 100644
--- a/src/core/ty.mli
+++ b/src/core/ty.mli
@@ -87,7 +87,7 @@ val ty_all : (ty -> bool) -> ty -> bool
 val ty_any : (ty -> bool) -> ty -> bool
 
 (** {3 symbol-wise map/fold} *)
-(** visites every symbol of the type} *)
+(** visits every symbol of the type} *)
 val ty_s_map : (tysymbol -> tysymbol) -> ty -> ty
 val ty_s_fold : ('a -> tysymbol -> 'a) -> 'a -> ty -> 'a
 val ty_s_all : (tysymbol -> bool) -> ty -> bool
diff --git a/src/util/plugin.mli b/src/util/plugin.mli
index f03e4efe33b549cc5a981ac84a7100279dd04aba..2af55c9a8cdd0658112205c4cabeb216c4bac00f 100644
--- a/src/util/plugin.mli
+++ b/src/util/plugin.mli
@@ -13,7 +13,6 @@ val load : ?dirs:string list -> plugin -> unit
    plugin named [plugin]. It add the extension .cmo or .cmxs to the
    filename according to the compilation used for the main program *)
 
-
 type plu =
   (* not a plugin extension *)
   | Plubad