diff --git a/csp/csp/hacs-demo-triples.rkt b/csp/csp/hacs-demo-triples.rkt
new file mode 100644
index 00000000..8b357e61
--- /dev/null
+++ b/csp/csp/hacs-demo-triples.rkt
@@ -0,0 +1,29 @@
+#lang br
+(require csp sugar)
+
+(define triples (make-csp))
+
+(add-var! triples 'a (range 10 50))
+(add-var! triples 'b (range 10 50))
+(add-var! triples 'c (range 10 50))
+
+(define (valid-triple? x y z)
+  (= (expt z 2) (+ (expt x 2) (expt y 2))))
+(add-constraint! triples valid-triple? '(a b c))
+
+(require math/number-theory)
+(add-constraint! triples coprime? '(a b c))
+
+(add-constraint! triples <= '(a b))
+
+(time-avg 10 (solve* triples))
+
+(define (f)
+  (for*/list ([a (in-range 10 50)]
+              [b (in-range 10 50)]
+              #:when (<= a b)
+              [c (in-range 10 50)]
+              #:when (and (coprime? a b c) (valid-triple? a b c)))
+             `((a . ,a) (b . ,b) (c . ,c))))
+
+(time-avg 10 (f))
\ No newline at end of file
diff --git a/csp/csp/hacs.rkt b/csp/csp/hacs.rkt
index 268301c3..c09405a5 100644
--- a/csp/csp/hacs.rkt
+++ b/csp/csp/hacs.rkt
@@ -489,7 +489,7 @@
                   #:select-variable [select-unassigned-variable
                                      (or (current-select-variable) first-unassigned-variable)]
                   #:order-values [order-domain-values (or (current-order-values) first-domain-value)]
-                  #:inference [inference (or (current-inference) no-inference)])
+                  #:inference [inference (or (current-inference) forward-check)])
   ((csp?) (#:select-variable procedure? #:order-values procedure? #:inference procedure?) . ->* . generator?)
   (generator ()
              (define reduce-arity-proc (if (current-arity-reduction) reduce-constraint-arity values))