1. click with the left button in the graph window
2. (define h (graph (current-graph-view)))
3. try that example again
If it complains about
Dr. Jon Berry Office: Whitley 204
Assistant Professor, Computing Sciences Campus Box: 2130
Elon College, N.C. 27244 Office Phone: (910)584-2290
On Fri, 21 Nov 1997, Graph Theory Project wrote:
> Hi:
> I tried the example "Link: Exploring Combinatorial Objects
>
> I typed the following language and has the error:
> STk> (define verts (set-vertex))
> #[undefined]
> STk> (define bev-test (string->regexp "Beverage"))
> #[undefined]
> STk> (define snack-test (string->regexp "Snack"))
> #[undefined]
> STk> (define (has-snack vlist)
> (cond ((null ? vlist) #f)
> (#t (or (snack-test (vertex-label (car vlist)))
> (has-snack (cdr vlist))))))
> #[undefined]
> STk> (define (has-bev vlist)
> (cond ((null ? vlist) #f )
> (#t (or (bev-test (vertex-label (car vlist)))
> (has-bev (cdr vlist))))))
> #[undefined]
> STk> (map (lambda (e)
> (if (and (has-bev (set-vertex->list (vertices e)))
> (has-snack (set-vertex->list (vertices e))))
> (set! verts (+ verts (vertices e)))))
> (set-edge->list (edges h)))
>
> *** Error:
> unbound variable: h
> STk> (define has-snack-or-bev (induced-subgraph h verts 1))
>
> *** Error:
> unbound variable: h
> STk> (define hsv (make <graph-view>:graph has-snack-or-bev
> :layout 'spring))
>
> *** Error:
> unbound variable: <graph-view>:graph
>
> can you tell me why?
>
> have a good weekend!
>
> Mei Liu
>
>