diff --git a/src/arachne.c b/src/arachne.c
index 14934f9..1819e16 100644
--- a/src/arachne.c
+++ b/src/arachne.c
@@ -6,9 +6,21 @@
  *
  */
 
+#include "term.h"
+#include "role.h"
 #include "system.h"
 #include "arachne.h"
 
+Term INTRUDER_ROLE;
+
+struct goalstruct
+{
+  int run;
+  int index;
+};
+
+typedef struct goalstruct Goal;
+
 //! Init Arachne engine
 void
 arachneInit (const System sys)
@@ -26,6 +38,87 @@ arachneDone (const System sys)
   return;
 }
 
+//------------------------------------------------------------------------
+// Detail
+//------------------------------------------------------------------------
+
+/*
+ * runs[rid].step is now the number of 'valid' events within the run, but we
+ * call it 'length' here.
+ */
+#define INVALID		-1
+#define isGoal(rd)	(rd->type == READ)
+#define isBound(rd)	(rd->bind_run != INVALID)
+#define length		step
+
+//------------------------------------------------------------------------
+// Sub
+//------------------------------------------------------------------------
+
+//------------------------------------------------------------------------
+// Larger logical componentents
+//------------------------------------------------------------------------
+
+//! Goal selection
+/**
+ * Should be ordered to prefer most constrained; for now, it is simply the first one encountered.
+ */
+Goal
+select_goal (const System sys)
+{
+  Goal goal;
+  int run;
+
+  goal.run = INVALID;
+  for (run = 0; run < sys->maxruns; run++)
+    {
+      Roledef rd;
+      int index;
+
+      index = 0;
+      rd = runPointerGet (sys, run);
+      while (rd != NULL && index < sys->runs[run].length)
+	{
+	  if (isGoal (rd) && !isBound (rd))
+	    {
+	      // Return this goal
+	      goal.run = run;
+	      goal.index = index;
+	      return goal;
+	    }
+	  index++;
+	  rd = rd->next;
+	}
+    }
+  return goal;
+}
+
+//! Bind a regular goal
+int
+bind_goal_regular (const System sys, const Goal goal)
+{
+}
+
+//! Bind an intruder goal
+int
+bind_goal_intruder (const System sys, const Goal goal)
+{
+}
+
+//! Bind a goal in all possible ways
+int
+bind_goal (const System sys, const Goal goal)
+{
+  if (isTermEqual (sys->runs[goal.run].protocol->nameterm, INTRUDER_ROLE))
+    {
+      return bind_goal_intruder (sys, goal);
+    }
+  else
+    {
+      return bind_goal_regular (sys, goal);
+    }
+}
+
 //! Prune determination
 /**
  *@returns true iff this state is invalid for some reason
@@ -36,10 +129,16 @@ prune (const System sys)
   return 0;
 }
 
+//------------------------------------------------------------------------
+// Main logic core
+//------------------------------------------------------------------------
+
 //! Main recursive procedure for Arachne
 int
 iterate (const System sys)
 {
+  Goal goal;
+
   /**
    * Possibly prune this state
    */
@@ -49,9 +148,23 @@ iterate (const System sys)
 
   /**
    * If not pruned, check whether its a final state (i.e. all goals bound)
-   * - Yes: check whether property holds
-   * - No:  iterate further
    */
+
+  goal = select_goal (sys);
+  if (goal.run == INVALID)
+    {
+      /*
+       * all goals bound, check for property
+       */
+      return 1;
+    }
+  else
+    {
+      /*
+       * bind this goal in all possible ways and iterate
+       */
+      return bind_goal (sys, goal);
+    }
 }
 
 //! Main code for Arachne