Appeal No. 1998-1389 Page 7
Application No. 08/553232
each source node, the ACG can be executed and its results are
displayed. Brotsky further discloses (col. 17, lines 20-24)
that when an operator inputs an instruction to execute the
ACG, a graph traversal algorithm is run, which walks the graph
from the leaf nodes to the root nodes. However, the displayed
image cannot be viewed directly. The operator must edit and
reexecute the ACG (col. 13, lines 55-58). Brotsky
additionally discloses (col. 22, lines 3-14) that
FIG. 17 is a flow diagram of the process for
executing the image formation process defined by an
ACG. In step 1531, an operator inputs an “execute
ACG” command. At this time, the structure walker
can determine whether the ACG is well formed in step
1532. A well formed ACG is a DAG all of whose
ports have at least one edge connected to them and
all of whose edges-obey the type restrictions of
their ports. If the ACG is not well formed, the
user is prompted in step 1533 so that they can edit
the ACG prior to reexecution. If the ACG is well
formed, operation proceeds to step 1534 where the
nodes of the ACG are evaluated from the fringes
(leafs) to the roots, as discussed above.
From our review of Brotsky, we find that the disclosure
(col. 8, lines 10-11) "[t]he ACG can be modified at any time"
refers to any time prior to or subsequent to the execution of
the ACG, but not during the execution (rendering) of the ACG.
When a "execute ACG" command is inputted (step 1531) the
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