From: Karl Lieberherr <lieber@ccs.neu.edu>
Subject: strategy graphs

Hi Kedar:

we need an elegant way to specify strategy graphs interactively in the context
of a class graph. We define the edges of strategy graphs by clicking on
from and to nodes in the class graph. Identical nodes in the
class graph correspond to identical nodes in the strategy graph.

For example, if we click in the class graph on node A
and then on B, we define a strategy graph edge x1:A->x2:B.
If we click again on B and then on C, we define a strategy edge
x2:B->x3:C.

Then we can define per strategy edge
the class graph edges which are excluded with bypassing and
only-through.

We can go back to earlier strategy graph edges by clicking on the desired edge
in the strategy graph description (textual).

Is this easy to add to the current system?

It is interesting that in this approach we can only define strategies 
where the node map is one to one. For example, we cannot define:

x1:A->x2:B
x2:B->x3:A

It is also interesting that Doug's implementation seems to allow
only strategies of this kind? Doug, is this correct? 

The strategy:

  C
 / \
A   B
 \ /
  D
(arrows from left to right) is represented by the syntax:

A->C
C->B
A->D
D->B

or by clicking in the class graph on
A(from) and then C(to) and then B(to)
A(from) and then D(to) and then B(to)


-- Karl