diff --git a/racket/syndicate/examples/actor/f-to-c4.rkt b/racket/syndicate/examples/actor/f-to-c4.rkt
new file mode 100644
index 0000000..21e18df
--- /dev/null
+++ b/racket/syndicate/examples/actor/f-to-c4.rkt
@@ -0,0 +1,39 @@
+#lang syndicate
+;; After the Fahrenheit-to-Celsius converter example in "Fabrik - A
+;; Visual Programming Environment", Ingalls, Wallace, Chow, Ludolph
+;; and Doyle, OOPSLA 1988.
+
+(struct temperature (unit value version) #:prefab)
+(struct set-temperature (unit value version) #:prefab)
+
+(spawn #:name 'track-celsius
+       (field [temp 0] [version 0])
+       (assert (temperature 'C (temp) (version)))
+       (on (message (set-temperature 'C $new-temp $v))
+           (when (> v (version))
+             (temp new-temp)
+             (version v))))
+
+(spawn #:name 'track-fahrenheit
+       (field [temp 32] [version 0])
+       (assert (temperature 'F (temp) (version)))
+       (on (message (set-temperature 'F $new-temp $v))
+           (when (> v (version))
+             (temp new-temp)
+             (version v))))
+
+(spawn #:name 'convert-C-to-F
+       (on (asserted (temperature 'C $other-temp $v))
+           (send! (set-temperature 'F (+ (* other-temp 9/5) 32) v))))
+
+(spawn #:name 'convert-F-to-C
+       (on (asserted (temperature 'F $other-temp $v))
+           (send! (set-temperature 'C (* (- other-temp 32) 5/9) v))))
+
+(spawn (on (asserted (temperature $unit $value $v))
+           (printf "Temperature in ~a at version ~a is ~a\n" unit v (exact->inexact value))))
+
+(spawn (on (asserted (observe (set-temperature _ _ _)))
+           (send! (set-temperature 'C 20 1))
+           (send! (set-temperature 'F 90 2))
+           ))
diff --git a/racket/syndicate/examples/actor/f-to-c5.rkt b/racket/syndicate/examples/actor/f-to-c5.rkt
new file mode 100644
index 0000000..bd4a2ff
--- /dev/null
+++ b/racket/syndicate/examples/actor/f-to-c5.rkt
@@ -0,0 +1,38 @@
+#lang syndicate
+;; After the Fahrenheit-to-Celsius converter example in "Fabrik - A
+;; Visual Programming Environment", Ingalls, Wallace, Chow, Ludolph
+;; and Doyle, OOPSLA 1988.
+
+;;---------------------------------------------------------------------------
+
+(define (make-idempotent-field name initial-value [=? equal?])
+  (local-require (submod syndicate/actor implementation-details))
+  (define f (make-field name initial-value))
+  (match-lambda*
+    [(list) (f)]
+    [(list new-value)
+     (unless (=? (field-ref (field-handle-desc f)) new-value)
+       (f new-value))]))
+
+(define-syntax-rule (idempotent-field [id init] ...)
+  (begin (define id (make-idempotent-field 'id init)) ...))
+
+;;---------------------------------------------------------------------------
+
+(struct temperature (unit value) #:prefab)
+(struct set-temperature (unit value) #:prefab)
+
+(spawn (idempotent-field [C 0] [F 32])
+       (begin/dataflow (F (+ (* (C) 9/5) 32)))
+       (begin/dataflow (C (* (- (F) 32) 5/9)))
+       (assert (temperature 'C (C)))
+       (assert (temperature 'F (F)))
+       (on (message (set-temperature 'C $v)) (C v))
+       (on (message (set-temperature 'F $v)) (F v)))
+
+(spawn (on (asserted (temperature $unit $value))
+           (printf "Temperature in ~a is ~a\n" unit (exact->inexact value))))
+
+(spawn (on (asserted (observe (set-temperature _ _)))
+           (send! (set-temperature 'C 20))
+           (send! (set-temperature 'F 90))))