diff --git a/sledge/src/fol.mli b/sledge/src/fol.mli
index 0beeb201a..f3d95cdd3 100644
--- a/sledge/src/fol.mli
+++ b/sledge/src/fol.mli
@@ -5,163 +5,65 @@
  * LICENSE file in the root directory of this source tree.
  *)
 
-(** Terms *)
-module Term : sig
-  type op1 =
-    | Signed of {bits: int}
-        (** [Ap1 (Signed {bits= n}, arg)] is [arg] interpreted as an [n]-bit
-            signed integer. That is, it two's-complement--decodes the low
-            [n] bits of the infinite two's-complement encoding of [arg]. *)
-    | Unsigned of {bits: int}
-        (** [Ap1 (Unsigned {bits= n}, arg)] is [arg] interpreted as an
-            [n]-bit unsigned integer. That is, it unsigned-binary--decodes
-            the low [n] bits of the infinite two's-complement encoding of
-            [arg]. *)
-    | Convert of {src: Llair.Typ.t; dst: Llair.Typ.t}
-        (** [Ap1 (Convert {src; dst}, arg)] is [arg] converted from type
-            [src] to type [dst], possibly with loss of information. The
-            [src] and [dst] types must be [Typ.convertible] and must not
-            both be [Integer] types. *)
-    | Splat  (** Iterated concatenation of a single byte *)
-    | Select of int  (** Select an index from a record *)
-  [@@deriving compare, equal, hash, sexp]
-
-  type op2 =
-    | Eq  (** Equal test *)
-    | Dq  (** Disequal test *)
-    | Lt  (** Less-than test *)
-    | Le  (** Less-than-or-equal test *)
-    | Ord  (** Ordered test (neither arg is nan) *)
-    | Uno  (** Unordered test (some arg is nan) *)
-    | Div  (** Division, for integers result is truncated toward zero *)
-    | Rem
-        (** Remainder of division, satisfies [a = b * div a b + rem a b] and
-            for integers [rem a b] has same sign as [a], and
-            [|rem a b| < |b|] *)
-    | Xor  (** Exclusive-or, bitwise *)
-    | Shl  (** Shift left, bitwise *)
-    | Lshr  (** Logical shift right, bitwise *)
-    | Ashr  (** Arithmetic shift right, bitwise *)
-    | Sized  (** Size-tagged sequence *)
-    | Update of int  (** Constant record with updated index *)
-  [@@deriving compare, equal, hash, sexp]
-
-  type op3 =
-    | Conditional  (** If-then-else *)
-    | Extract  (** Extract a slice of an sequence value *)
-  [@@deriving compare, equal, hash, sexp]
-
-  type opN =
-    | Concat  (** Byte-array concatenation *)
-    | Record  (** Record (array / struct) constant *)
-  [@@deriving compare, equal, hash, sexp]
-
-  module rec Set : sig
-    include NS.Set.S with type elt := T.t
+(** Variables *)
+module Var : sig
+  type t [@@deriving compare, equal, hash, sexp]
+  type strength = t -> [`Universal | `Existential | `Anonymous] option
 
-    val hash_fold_t : t Hash.folder
-    val t_of_sexp : Sexp.t -> t
-  end
+  val pp : t pp
+
+  module Map : Map.S with type key := t
 
-  and Qset : sig
-    include NS.Qset.S with type elt := T.t
+  module Set : sig
+    include NS.Set.S with type elt := t
 
     val hash_fold_t : t Hash.folder
+    val sexp_of_t : t -> Sexp.t
     val t_of_sexp : Sexp.t -> t
+    val ppx : strength -> t pp
+    val pp : t pp
+    val pp_xs : t pp
+    val of_regs : Llair.Reg.Set.t -> t
   end
 
-  and T : sig
-    type set = Set.t [@@deriving compare, equal, hash, sexp]
-
-    type qset = Qset.t [@@deriving compare, equal, hash, sexp]
-
-    and t = private
-      | Var of {id: int; name: string}
-          (** Local variable / virtual register *)
-      | Ap1 of op1 * t  (** Unary application *)
-      | Ap2 of op2 * t * t  (** Binary application *)
-      | Ap3 of op3 * t * t * t  (** Ternary application *)
-      | ApN of opN * t iarray  (** N-ary application *)
-      | And of set  (** Conjunction, boolean or bitwise *)
-      | Or of set  (** Disjunction, boolean or bitwise *)
-      | Add of qset  (** Sum of terms with rational coefficients *)
-      | Mul of qset  (** Product of terms with rational exponents *)
-      | Label of {parent: string; name: string}
-          (** Address of named code block within parent function *)
-      | Float of {data: string}  (** Floating-point constant *)
-      | Integer of {data: Z.t}  (** Integer constant *)
-      | Rational of {data: Q.t}  (** Rational constant *)
-      | RecRecord of int  (** Reference to ancestor recursive record *)
-    [@@deriving compare, equal, hash, sexp]
-  end
-
-  include module type of T with type t = T.t
+  val of_reg : Llair.Reg.t -> t
+  val fresh : string -> wrt:Set.t -> t * Set.t
 
-  module Var : sig
-    type term := t
-    type t = private term [@@deriving compare, equal, hash, sexp]
-    type strength = t -> [`Universal | `Existential | `Anonymous] option
+  val identified : name:string -> id:int -> t
+  (** Variable with the given [id]. Variables are compared by [id] alone,
+      [name] is used only for printing. The only way to ensure [identified]
+      variables do not clash with [fresh] variables is to pass the
+      [identified] variables to [fresh] in [wrt]:
+      [Var.fresh name ~wrt:(Var.Set.of_ (Var.identified ~name ~id))]. *)
 
-    module Map : Map.S with type key := t
+  val id : t -> int
+  val name : t -> string
 
-    module Set : sig
-      include NS.Set.S with type elt := t
-
-      val hash_fold_t : t Hash.folder
-      val sexp_of_t : t -> Sexp.t
-      val t_of_sexp : Sexp.t -> t
-      val ppx : strength -> t pp
-      val pp : t pp
-      val pp_xs : t pp
-      val of_regs : Llair.Reg.Set.t -> t
-    end
+  module Subst : sig
+    type var := t
+    type t [@@deriving compare, equal, sexp]
+    type x = {sub: t; dom: Set.t; rng: Set.t}
 
     val pp : t pp
-
-    include Invariant.S with type t := t
-
-    val name : t -> string
-    val id : t -> int
-    val of_ : term -> t
-    val of_term : term -> t option
-    val of_reg : Llair.Reg.t -> t
-    val fresh : string -> wrt:Set.t -> t * Set.t
-
-    val identified : name:string -> id:int -> t
-    (** Variable with the given [id]. Variables are compared by [id] alone,
-        [name] is used only for printing. The only way to ensure
-        [identified] variables do not clash with [fresh] variables is to
-        pass the [identified] variables to [fresh] in [wrt]:
-        [Var.fresh name ~wrt:(Var.Set.of_ (Var.identified ~name ~id))]. *)
-
-    module Subst : sig
-      type var := t
-      type t [@@deriving compare, equal, sexp]
-      type x = {sub: t; dom: Set.t; rng: Set.t}
-
-      val pp : t pp
-      val empty : t
-      val freshen : Set.t -> wrt:Set.t -> x * Set.t
-      val invert : t -> t
-      val restrict : t -> Set.t -> x
-      val is_empty : t -> bool
-      val domain : t -> Set.t
-      val range : t -> Set.t
-      val apply : t -> var -> var
-      val fold : t -> init:'a -> f:(var -> var -> 'a -> 'a) -> 'a
-    end
+    val empty : t
+    val freshen : Set.t -> wrt:Set.t -> x * Set.t
+    val invert : t -> t
+    val restrict : t -> Set.t -> x
+    val is_empty : t -> bool
+    val domain : t -> Set.t
+    val range : t -> Set.t
+    val fold : t -> init:'a -> f:(var -> var -> 'a -> 'a) -> 'a
   end
+end
 
-  module Map : sig
-    include Map.S with type key := t
-
-    val t_of_sexp : (Sexp.t -> 'a) -> Sexp.t -> 'a t
-  end
+(** Terms *)
+module Term : sig
+  type t [@@deriving compare, equal, hash, sexp]
 
   val ppx : Var.strength -> t pp
   val pp : t pp
-  val pp_diff : (t * t) pp
-  val invariant : t -> unit
+
+  module Map : Map.S with type key := t
 
   (** Construct *)
 
@@ -169,29 +71,18 @@ module Term : sig
   val var : Var.t -> t
 
   (* constants *)
-  val label : parent:string -> name:string -> t
-  val bool : bool -> t
   val true_ : t
   val false_ : t
   val integer : Z.t -> t
   val zero : t
   val one : t
-  val minus_one : t
   val rational : Q.t -> t
-  val float : string -> t
-
-  (* type conversions *)
-  val signed : int -> t -> t
-  val unsigned : int -> t -> t
-  val convert : Llair.Typ.t -> to_:Llair.Typ.t -> t -> t
 
   (* comparisons *)
   val eq : t -> t -> t
   val dq : t -> t -> t
   val lt : t -> t -> t
   val le : t -> t -> t
-  val ord : t -> t -> t
-  val uno : t -> t -> t
 
   (* arithmetic *)
   val neg : t -> t
@@ -199,39 +90,21 @@ module Term : sig
   val sub : t -> t -> t
   val mulq : Q.t -> t -> t
   val mul : t -> t -> t
-  val div : t -> t -> t
-  val rem : t -> t -> t
 
-  (* boolean / bitwise *)
+  (* boolean *)
   val and_ : t -> t -> t
   val or_ : t -> t -> t
   val not_ : t -> t
 
-  (* bitwise *)
-  val xor : t -> t -> t
-  val shl : t -> t -> t
-  val lshr : t -> t -> t
-  val ashr : t -> t -> t
-
   (* if-then-else *)
   val conditional : cnd:t -> thn:t -> els:t -> t
 
-  (* sequence sizes *)
-  val seq_size_exn : t -> t
-  val seq_size : t -> t option
-
   (* sequences *)
   val splat : t -> t
   val sized : seq:t -> siz:t -> t
   val extract : seq:t -> off:t -> len:t -> t
   val concat : t array -> t
 
-  (* records (struct / array values) *)
-  val record : t iarray -> t
-  val select : rcd:t -> idx:int -> t
-  val update : rcd:t -> idx:int -> elt:t -> t
-  val rec_record : int -> t
-
   (* convert *)
   val of_exp : Llair.Exp.t -> t
 
@@ -245,52 +118,20 @@ module Term : sig
 
   (** Transform *)
 
-  val map : t -> f:(t -> t) -> t
-
-  val map_rec_pre : t -> f:(t -> t option) -> t
-  (** Pre-order transformation. Each subterm [x] from root to leaves is
-      presented to [f]. If [f x = Some x'] then the subterms of [x] are not
-      traversed and [x] is transformed to [x']. Otherwise traversal proceeds
-      to the subterms of [x], followed by rebuilding the term structure on
-      the transformed subterms. *)
-
-  val fold_map : t -> init:'a -> f:('a -> t -> 'a * t) -> 'a * t
-
-  val fold_map_rec_pre :
-    t -> init:'a -> f:('a -> t -> ('a * t) option) -> 'a * t
-
   val disjuncts : t -> t list
   val rename : Var.Subst.t -> t -> t
 
   (** Traverse *)
 
-  val iter : t -> f:(t -> unit) -> unit
-  val exists : t -> f:(t -> bool) -> bool
-  val fold : t -> init:'a -> f:(t -> 'a -> 'a) -> 'a
   val fold_vars : t -> init:'a -> f:('a -> Var.t -> 'a) -> 'a
-  val fold_terms : t -> init:'a -> f:('a -> t -> 'a) -> 'a
 
   (** Query *)
 
   val fv : t -> Var.Set.t
   val is_true : t -> bool
   val is_false : t -> bool
-
-  val is_constant : t -> bool
-  (** Test if a term's semantics is independent of the values of variables. *)
-
-  val height : t -> int
-
-  (** Solve *)
-
-  val solve_zero_eq : ?for_:t -> t -> (t * t) option
-  (** [solve_zero_eq d] is [Some (e, f)] if [d = 0] can be equivalently
-      expressed as [e = f] for some monomial subterm [e] of [d]. If [for_]
-      is passed, then the subterm [e] must be [for_]. *)
 end
 
-module Var = Term.Var
-
 (** Inference System *)
 module Context : sig
   type t [@@deriving compare, equal, sexp]
@@ -313,18 +154,12 @@ module Context : sig
   val true_ : t
   (** The diagonal relation, which only equates each term with itself. *)
 
-  val and_eq : Var.Set.t -> Term.t -> Term.t -> t -> Var.Set.t * t
-  (** Conjoin an equation to a relation. *)
-
   val and_term : Var.Set.t -> Term.t -> t -> Var.Set.t * t
   (** Conjoin a (Boolean) term to a relation. *)
 
   val and_ : Var.Set.t -> t -> t -> Var.Set.t * t
   (** Conjunction. *)
 
-  val or_ : Var.Set.t -> t -> t -> Var.Set.t * t
-  (** Disjunction. *)
-
   val orN : Var.Set.t -> t list -> Var.Set.t * t
   (** Nary disjunction. *)
 
@@ -361,7 +196,7 @@ module Context : sig
 
   (** Solution Substitutions *)
   module Subst : sig
-    type t [@@deriving compare, equal, sexp]
+    type t
 
     val pp : t pp
     val is_empty : t -> bool
@@ -392,8 +227,4 @@ module Context : sig
   val elim : Var.Set.t -> t -> t
   (** Weaken relation by removing oriented equations [k ↦ _] for [k] in
       [ks]. *)
-
-  (* Replay debugging *)
-
-  val replay : string -> unit
 end
diff --git a/sledge/src/sh_test.ml b/sledge/src/sh_test.ml
index 8e4185e17..d421462a2 100644
--- a/sledge/src/sh_test.ml
+++ b/sledge/src/sh_test.ml
@@ -25,7 +25,8 @@ let%test_module _ =
     let ( ! ) i = Term.integer (Z.of_int i)
     let ( - ) = Term.sub
     let ( = ) = Term.eq
-    let f = Term.unsigned 8
+    let f = Term.splat (* any uninterpreted function *)
+
     let wrt = Var.Set.empty
     let a_, wrt = Var.fresh "a" ~wrt
     let b_, wrt = Var.fresh "b" ~wrt
@@ -146,11 +147,11 @@ let%test_module _ =
       pp q' ;
       [%expect
         {|
-        ∃ %x_6 .   %x_6 = ((u8) %x_6) ∧ (%y_7 + -1) = ((u8) %y_7) ∧ emp
+        ∃ %x_6 .   %x_6 = %x_6^ ∧ (%y_7 + -1) = %y_7^ ∧ emp
 
-          (%y_7 + -1) = ((u8) %y_7) ∧ (((u8) %y_7) = (%y_7 + -1)) ∧ emp
+          (%y_7 + -1) = %y_7^ ∧ (%y_7^ = (%y_7 + -1)) ∧ emp
 
-          (%y_7 + -1) = ((u8) %y_7) ∧ emp |}]
+          (%y_7 + -1) = %y_7^ ∧ emp |}]
 
     let%expect_test _ =
       let q =