update

csp/csp/hacs-test.rkt

@@ -19,25 +19,25 @@
  (csp-vars (forward-check (csp (list (avar 'a '(1)) (var 'b (range 2))) null) 'a))
  (list (avar 'a '(1)) (var 'b '(0 1))))
 
-#;(check-equal?
+(check-equal?
  (csp-vars (forward-check (forward-check (csp (list (avar 'a '(1))  (avar 'b '(0)) (var 'c '(0 1 2)))
                                                 (list (constraint '(a c) (negate =))
                                                       (constraint '(b c) (negate =)))) 'a) 'b))
- (list (avar 'a '(1)) (avar 'b '(0)) (cvar 'c '(2) '(b a))))
+ (list (avar 'a '(1)) (avar 'b '(0)) (cvar 'c '(2) '((b . 0) (a . 1)))))
 
-#;(check-equal?
+(check-equal?
  ;; no inconsistency: b≠c not checked when fc is relative to a
  (csp-vars (forward-check (csp (list (avar 'a '(1))  (var 'b (range 2)) (var 'c '(0)))
                                  (list (constraint '(a b) (negate =))
                                        (constraint '(b c) (negate =)))) 'a))
- (list (avar 'a '(1)) (cvar 'b '(0) '(a)) (var 'c '(0))))
+ (list (avar 'a '(1)) (cvar 'b '(0) '((a . 1))) (var 'c '(0))))
 
-#;(check-equal?
+(check-equal?
  ;; no inconsistency: a≠b not checked when fc ignores a, which is already assigned
  (csp-vars (forward-check (csp (list (avar 'a '(1))  (avar 'b '(1)) (var 'c (range 2)))
                                  (list (constraint '(a b) (negate =))
                                        (constraint '(b c) (negate =)))) 'b))
- (list (avar 'a '(1)) (avar 'b '(1)) (cvar 'c '(0) '(b))))
+ (list (avar 'a '(1)) (avar 'b '(1)) (cvar 'c '(0) '((b . 1)))))
 
 (check-exn backtrack?
            (λ () (csp-vars (forward-check (csp (list (avar 'a '(1))
@@ -45,10 +45,10 @@
                                                  (list (constraint '(a b) (negate =)))) 'a))))
 
 
-#;(check-equal? (csp-vars (forward-check (csp (list (var 'a '(0))
+(check-equal? (csp-vars (forward-check (csp (list (var 'a '(0))
                                                     (var 'b (range 3)))
                                               (list (constraint '(a b) <))) 'a))
-              (list (var 'a '(0)) (cvar 'b '(1 2) '(a))))
+              (list (var 'a '(0)) (cvar 'b '(1 2) '((a . 0)))))
 
 (check-equal?
  (parameterize ([current-inference forward-check])

csp/csp/hacs.rkt

@@ -244,6 +244,11 @@
   (var? . -> . natural?)
   (length (domain var)))
 
+(define/contract (state-count csp)
+  (csp? . -> . natural?)
+  (for/product ([var (in-vars csp)])
+    (domain-length var)))
+
 (define/contract (mrv-degree-hybrid prob)
   (csp? . -> . (or/c #f var?))
   (match (unassigned-vars prob)
@@ -649,8 +654,8 @@
           . ->* . (or/c #false any/c))
   (match (solve* prob #:finish-proc finish-proc #:solver solver #:limit max-solutions)
     [(list solution) solution]
-    [(list solutions ...) solutions]
-    [else #false]))
+    [(list) #false]
+    [(list solutions ...) solutions]))
 
 (define (<> a b) (not (= a b)))
 (define (neq? a b) (not (eq? a b)))