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diff --git a/topics/_week10_gsv.mdwn b/topics/_week10_gsv.mdwn
index c557d08b..1cd25a80 100644
--- a/topics/_week10_gsv.mdwn
+++ b/topics/_week10_gsv.mdwn
@@ -56,7 +56,8 @@ unary modality (box and diamond, corresponding to epistemic necessity
 and epistemic possibility).
 
 An implementation in OCaml is available [[here|code/gsv.ml]]; consult
-that code for details of syntax, types, and values.
+that code for details of syntax, types, and values.  [[An implementation
+in Haskell|code/gsv.hs]] is available as well, if you prefer.
 
 Terms in this language are either individuals such as Alice or Bob, or
 else variables.  So in general, the referent of a term can depend on a
@@ -545,5 +546,49 @@ fact, their system is careful designed to guarantee that every
 variable is assigned a discourse referent distinct from all previous
 discourse referents.
 
-End of digression on pegs.
-
+The addition of pegs tracks an active discussion in the dynamic
+literature around the time of publication of the paper.  Groenendijk
+and Stokhof (Two theories of dynamic semantics, 1989) noted that it
+was possible in DPL for information to be "lost".
+
+    18. (∃x.P(x)) & (∃x.Q(x)) & R(x)
+
+If the two existentials happen to bind the same variable (here, "x"),
+then the second existential occludes the first.  That is, at the point
+at which we evalute R(x), all of the assignment functions will be
+mapping the variable "x" to objects that have property Q.  The
+information that there exist objects with property P has been lost.
+If you want your dynamic system to be eliminative---or in more general
+terms, if you want the amount of information embodied by an updated
+information state to be monotonically increasing---then this is a
+problem.  
+
+A syntactic solution is to require that the variable bound
+by an existential to be chosen fresh.
+
+Vermeulen, Cees FM. "Merging without mystery or: Variables in dynamics
+semantics." Journal of Philosophical Logic 24.4 (1995): 405-450 offers
+a different approach, one based on *referent systems*.  GSV's pegs are
+a referent system.  In the pegs system, when (18) is processed, the
+information that there is an object that has property P is maintained
+in the information state.  Curiously, however, there is still no way
+to refer to that object, at least, not with a variable, since there is
+no variable that is associated with the peg that points to the
+relevant object.  So the information is present, but not accessible. 
+
+That does not mean that there aren't other expression types that are
+able to latch onto peg.  An intriguing suggestion based on an example
+in Vermeulen is that "former" might be able to provide access to a
+hidden peg:
+
+    19. Someone entered.  Someone spoke.  The former was a woman.
+
+Presumably we want *the former* to be able to pick out the person who
+entered, whether or not the two existentials bind the same variable or
+not.  If we allow "former" to latch onto the second most recently
+established peg, no matter whether there is a variable still pointing
+to that peg, the desired effect is achieved. 
+
+But none of this is relevant for any of the explanations or analyses
+provide by the GSV fragment, and it is considerably simpler to see
+what their fragment is about if we leave referent systems out of it.