diff --git a/collects/tests/typed-scheme/fail/dead-substruct.rkt b/collects/tests/typed-scheme/fail/dead-substruct.rkt
new file mode 100644
index 00000000..eed75288
--- /dev/null
+++ b/collects/tests/typed-scheme/fail/dead-substruct.rkt
@@ -0,0 +1,16 @@
+#;
+(exn-pred 1)
+#lang typed/scheme
+
+(define-struct: parent ((x : Integer)))
+(define-struct: (child1 parent) ((y : Integer)))
+(define-struct: (child2 parent) ((y : Float)))
+
+(: f (parent -> Integer))
+(define (f x)
+  (cond [(child1? x) (+ "a" "b")] ; rhs was considered dead code
+        [(child2? x) 2]
+        [else (error "eh?")]))
+
+(f (make-child1 1 2))
+(f (make-child2 1 2.0))
diff --git a/collects/tests/typed-scheme/optimizer/generic/dead-substructs.rkt b/collects/tests/typed-scheme/optimizer/generic/dead-substructs.rkt
new file mode 100644
index 00000000..a01a5e5b
--- /dev/null
+++ b/collects/tests/typed-scheme/optimizer/generic/dead-substructs.rkt
@@ -0,0 +1,17 @@
+#lang typed/scheme #:optimize
+
+;; originally from nucleic3
+;; cond on substructs, branches were considered dead
+
+(define-struct: parent ((x : Integer)))
+(define-struct: (child1 parent) ((y : Integer)))
+(define-struct: (child2 parent) ((y : Float)))
+
+(: f (parent -> Integer))
+(define (f x)
+  (cond [(child1? x) 1]
+        [(child2? x) 2]
+        [else (error "eh?")]))
+
+(f (make-child1 1 2))
+(f (make-child2 1 2.0))
diff --git a/collects/tests/typed-scheme/succeed/priority-queue.scm b/collects/tests/typed-scheme/succeed/priority-queue.scm
index 091a284d..9454a314 100644
--- a/collects/tests/typed-scheme/succeed/priority-queue.scm
+++ b/collects/tests/typed-scheme/succeed/priority-queue.scm
@@ -65,15 +65,15 @@
 ;; "bug" found - handling of empty heaps
 (pdefine: (a) (find-min [pq : (priority-queue a)]) : a 
 	  (let ([h (heap pq)])
-	    (if (heap:heap-node? h)
-		(elm (heap:find-min h))
-		(error "priority queue empty"))))
+            (if (heap:empty? h)
+                (error "priority queue empty")
+                (elm (heap:find-min h)))))
 
 (pdefine: (a) (find-min-priority [pq : (priority-queue a)]) : number
 	  (let ([h (heap pq)])
-	    (if (heap:heap-node? h)
-		(pri (heap:find-min h))
-		(error "priority queue empty"))))
+	    (if (heap:empty? h)
+		(error "priority queue empty")
+                (pri (heap:find-min h)))))
 
 (pdefine: (a) (insert [x : a] [p : number] [pq : (priority-queue a)]) : (priority-queue a)
 	  (make (heap:insert (cons p x) (heap pq))))
@@ -84,9 +84,9 @@
 
 (pdefine: (a) (delete-min [pq : (priority-queue a)]) : (priority-queue a)
 	  (let ([h (heap pq)])
-	    (if (heap:heap-node? h)
-		(make (heap:delete-min h))
-		(error "priority queue empty"))))
+	    (if (heap:empty? h)
+                (error "priority queue empty")
+		(make (heap:delete-min h)))))
 
 
 (pdefine: (a) (size [pq : (priority-queue a)]) : number
diff --git a/collects/tests/typed-scheme/xfail/priority-queue.scm b/collects/tests/typed-scheme/xfail/priority-queue.scm
new file mode 100644
index 00000000..091a284d
--- /dev/null
+++ b/collects/tests/typed-scheme/xfail/priority-queue.scm
@@ -0,0 +1,101 @@
+#lang typed-scheme
+;;; priority-queue.scm  --  Jens Axel Søgaard
+;;; PURPOSE
+
+; This file implements priority queues on top of
+; a heap library.
+(define-type-alias number Number)
+(define-type-alias boolean Boolean)
+(define-type-alias symbol Symbol)
+(define-type-alias top Any)
+(define-type-alias list-of Listof)
+(require (prefix-in heap: "leftist-heap.ss")
+	 (except-in (lib "67.ss" "srfi") number-compare current-compare =? <?)
+	 (only-in "leftist-heap.ss" comparator))
+(require/typed number-compare (number number -> number) (lib "67.ss" "srfi"))
+(require/typed current-compare (-> (top top -> number)) (lib "67.ss" "srfi"))
+(require/typed =? ((top top -> number) top top -> boolean) (lib "67.ss" "srfi"))
+(require/typed <? ((top top -> number) top top -> boolean) (lib "67.ss" "srfi"))
+
+; a priority-queue is a heap of  (cons <priority> <element>)
+
+(define-type-alias (elem a) (cons number a))
+
+(define-typed-struct (a) priority-queue ([heap : (heap:Heap (elem a))]))
+
+(define-type-alias (pqh a) (heap:Heap (elem a)))
+
+; conveniences
+(pdefine: (a) (heap [pq : (priority-queue a)]) : (pqh a) (priority-queue-heap pq))
+(pdefine: (a) (pri [p : (elem a)]) : number (car p))
+(pdefine: (a) (elm [p : (elem a)]) : a  (cdr p))
+(pdefine: (a) (make [h : (pqh a)]) : (priority-queue a)  (make-priority-queue h))
+
+; sort after priority
+; TODO: and then element?
+(pdefine: (a) (compare [p1 : (elem a)] [p2 : (elem a)]) : number
+	  (number-compare (pri p1) (pri p2)))
+
+;;; OPERATIONS
+
+(define: (num-elems [h : (heap:Heap (cons number number))]) : (list-of (cons number number))
+  (heap:elements h))
+
+(pdefine: (a) (elements [pq : (priority-queue a)]) : (list-of a)
+          (map #{elm :: ((elem a) -> a)} (heap:elements (heap pq))))
+
+(pdefine: (a) (elements+priorities [pq : (priority-queue a)]) : (values (list-of a) (list-of number))
+	  (let: ([eps : (list-of (elem a)) (heap:elements (heap pq))])
+		(values (map #{elm :: ((elem a) -> a)} eps)
+			(map #{pri :: ((elem a) -> number)} eps))))
+
+(pdefine: (a) (empty? [pq : (priority-queue a)]) : boolean
+	  (heap:empty? (heap pq)))
+
+(define: empty : (All (a) (case-lambda (-> (priority-queue a)) (comparator -> (priority-queue a))))
+  (pcase-lambda: (a)
+		 [()    (#{empty @ a} (current-compare))]
+		 [([cmp : comparator]) (make (#{heap:empty :: (case-lambda (-> (pqh a))
+									   (comparator -> (pqh a)))} cmp))]))
+
+(pdefine: (e r) (fold [f : ((cons number e) r -> r)] [b : r] [a : (priority-queue e)]) : r
+	  (heap:fold f b (#{heap :: ((priority-queue e) -> (pqh e))} a)))
+
+
+;; "bug" found - handling of empty heaps
+(pdefine: (a) (find-min [pq : (priority-queue a)]) : a 
+	  (let ([h (heap pq)])
+	    (if (heap:heap-node? h)
+		(elm (heap:find-min h))
+		(error "priority queue empty"))))
+
+(pdefine: (a) (find-min-priority [pq : (priority-queue a)]) : number
+	  (let ([h (heap pq)])
+	    (if (heap:heap-node? h)
+		(pri (heap:find-min h))
+		(error "priority queue empty"))))
+
+(pdefine: (a) (insert [x : a] [p : number] [pq : (priority-queue a)]) : (priority-queue a)
+	  (make (heap:insert (cons p x) (heap pq))))
+
+;; FIXME -- too many annotations needed on cons
+(pdefine: (a) (insert* [xs : (list-of a)] [ps : (list-of number)] [pq : (priority-queue a)]) : (priority-queue a)
+          (make (heap:insert* (map #{cons @ number a} ps xs) (heap pq))))
+
+(pdefine: (a) (delete-min [pq : (priority-queue a)]) : (priority-queue a)
+	  (let ([h (heap pq)])
+	    (if (heap:heap-node? h)
+		(make (heap:delete-min h))
+		(error "priority queue empty"))))
+
+
+(pdefine: (a) (size [pq : (priority-queue a)]) : number
+	  (heap:size (heap pq)))
+
+(pdefine: (a) (union [pq1 : (priority-queue a)] [pq2 : (priority-queue a)]) : (priority-queue a)
+	  (make (heap:union (heap pq1) (heap pq2))))
+
+
+#;(require "signatures/priority-queue-signature.scm")
+#;(provide-priority-queue)
+
diff --git a/collects/typed-scheme/types/remove-intersect.rkt b/collects/typed-scheme/types/remove-intersect.rkt
index 074af5da..64d55e8f 100644
--- a/collects/typed-scheme/types/remove-intersect.rkt
+++ b/collects/typed-scheme/types/remove-intersect.rkt
@@ -24,7 +24,8 @@
          [(list (F: _) _) #t]
          [(list _ (F: _)) #t]
          [(list (Name: n) (Name: n*)) 
-          (overlap (resolve-once t1) (resolve-once t2))]
+          (or (free-identifier=? n n*)
+              (overlap (resolve-once t1) (resolve-once t2)))]
          [(list (? Mu?) _) (overlap (unfold t1) t2)]
          [(list _ (? Mu?)) (overlap t1 (unfold t2))]
          [(list (Union: e) t)
@@ -73,8 +74,8 @@
                 (and t2 (Struct: n* p* flds* _ _ _ _ _)))
           (let ([p1 (if (Name? p) (resolve-name p) p)]
                 [p2 (if (Name? p*) (resolve-name p*) p*)])
-            (or (overlap t1 p2)
-                (overlap t2 p1)
+            (or (and p2 (overlap t1 p2))
+                (and p1 (overlap t2 p1))
                 (and (= (length flds) (length flds*)) 
                      (for/and ([f flds] [f* flds*]) 
                        (match* (f f*)