+ (define (clashes)
+ (define (gen acc x)
+ (if (assoc (car x) a)
+ (cons (cons (car x) (most-concrete (cdr (assoc (car x) a))
+ (cdr x)))
+ acc)
+ acc))
+ (fold-left gen '() b))
+
+ ;; (define (union p q)
+ ;; (cond
+ ;; [(null? p) q]
+ ;; [(null? q) p]
+ ;; [else
+ ;; (let ([x (car q)])
+ ;; (if (assoc (car x) p)
+ ;; (if (eqv? (most-concrete (cddr (assoc (car x) p))
+ ;; (cdr x))
+ ;; (cdr x))
+ ;; (cons x (union (filter (p) (not (eqv?