#-(and)"
P83 (**) Construct all spanning trees
Write a predicate s-tree(Graph,Tree) to construct (by
backtracking) all spanning trees of a given graph. With this
predicate, find out how many spanning trees there are for the
graph depicted to the left. The data of this example graph can be
found in the file p83.dat. When you have a correct solution for
the s-tree/2 predicate, use it to define two other useful
predicates: is-tree(Graph) and is-connected(Graph). Both are
five-minutes tasks!
"
(load "p80.lisp")
(defparameter *p83-example-graph*
(make-edge-graph '((a b) (a d)
(b c) (b e)
(c e)
(d e) (d f) (d g)
(e h)
(f g)
(g h))))