#-(and)"
P84 (**) Construct the minimal spanning tree
Write a predicate ms-tree(Graph,Tree,Sum) to construct the minimal
spanning tree of a given labelled graph. Hint: Use the algorithm
of Prim. A small modification of the solution of P83 does the
trick. The data of the example graph to the right can be found in
the file p84.dat.
"
(load "p80.lisp")
(defparameter *p84-example-graph*
(make-weighted-edge-graph '((a b 5) (a d 3)
(b c 2) (b e 4)
(c e 6)
(d e 7) (d f 4) (d g 3)
(e h 5)
(f g 4)
(g h 1))))