diff --git a/bin/day2423.ml b/bin/day2423.ml
index 68eb174..7171595 100644
--- a/bin/day2423.ml
+++ b/bin/day2423.ml
@@ -53,7 +53,7 @@ let rec find_rings acc visited connections = function
 
 (** [starts_with_t set] returns true if any member of [set] starts with the
     letter ['t']. *)
-let starts_with_t set = StringSet.exists (fun x -> x.[0] = 't') set
+let starts_with_t = StringSet.exists (fun x -> x.[0] = 't')
 
 let part1 connections =
   StringMap.to_list connections
@@ -61,27 +61,6 @@ let part1 connections =
   |> find_rings [] StringSet.empty connections
   |> List.filter starts_with_t |> List.length |> string_of_int
 
-(** [search_candidate max_lst connections current candidates] searches for the
-    longest star network that contains all the computers in [current] and maybe
-    some of the elements of [candidates].
-
-    [max_lst] is the biggest network found so far. [connections] is the map of
-    computers to direct connections.
-
-    The initial call should look something like:
-
-    [search_candidate [] connections k (StringSet.to_list (StringMap.find k
-     connections))] *)
-let rec search_candidate max_lst connections current candidates =
-  match candidates with
-  | [] -> if List.length current > List.length max_lst then current else max_lst
-  | h :: t ->
-      let map = StringMap.find h connections in
-      let current' = h :: current in
-      let candidates' = List.filter (Fun.flip StringSet.mem map) candidates in
-      let max_lst = search_candidate max_lst connections current' candidates' in
-      search_candidate max_lst connections current t
-
 (** [find_max_set connections] returns a list containing the largest number of
     computers in a star network (that is for every pair of elements in the list
     there is a connection between them).
@@ -92,14 +71,21 @@ let rec search_candidate max_lst connections current candidates =
     [StringSet.mem b (StringMap.find a connections)]. Note that
     [StringSet.mem a (StringMap.find a connections)] must return [false]. *)
 let find_max_set connections =
-  let rec impl max_lst = function
-    | [] -> max_lst
-    | (k, v) :: t ->
-        impl
-          (search_candidate max_lst connections [ k ] (StringSet.to_list v))
-          t
+  let rec search_candidate max_lst current candidates =
+    (* recursion invariant: all nodes in the list [current] are in a clique with
+       each other.  [current] unioned with any individual element of 
+       [candidates] is also a valid clique. *)
+    match candidates with
+    | [] ->
+        if List.length current > List.length max_lst then current else max_lst
+    | h :: t ->
+        let map = StringMap.find h connections in
+        let current' = h :: current in
+        let candidates' = List.filter (Fun.flip StringSet.mem map) candidates in
+        let max_lst = search_candidate max_lst current' candidates' in
+        search_candidate max_lst current t
   in
-  impl [] (StringMap.to_list connections)
+  StringMap.to_list connections |> List.map fst |> search_candidate [] []
 
 let part2 connections =
   find_max_set connections |> List.sort compare |> String.concat ","