;; graph sum

(define g  (graph '(1 2 3) '((1 2) (1 3) (2 3))))
(define g2 (graph '(2 3 4) '((2 3) (3 4))))

(describe (graph (+ (vertices g) (vertices g2))  ; the vertex and edge
                 (+ (edges g) (edges g2))))	 ; sets are Collection
						 ; objects - apply set
						 ; primitive operations
