Information Technology Reference
In-Depth Information
Introduce an action node
n
i
into the diagram, labeled with the
name of service
w
, draw a connector from
n
t
to it, and
compute
S
i
of
n
i
;
21.
NS
t
¼
NS
t
[f
n
i
g
22.
;
23.
end for
NS
0
¼
NS
0
[
NS
t
f
NS
t
f
24.
n
t
g
;
NS
¼
NS
[
n
t
g
;
there is some node
n
l
2
NS
t
, such that the truth value of
Cond
can be found to be true under its corresponding state
S
l
25.
if
then
26.
Introduce a decision node into the diagram, and draw a
connector from
n
l
to it;
27.
flag
¼ true
;
28.
Exit
the
while
loop;
29.
end if
30.
end if
31.
end while
32.
end if
33.
¼ true then
34. Draw a connector from the decision node to
n
0
A
, set a guard along
this new connector with the condition
Cond
, then delete the
original connector pointed to it;
35. Draw a connector from the decision node to
n
0
A
, set a guard along
this new connector with the condition
:
if
flag
Cond
, then delete the
original connector pointed to it. Note that
:
Cond
means
Cond
's complement.
36.
Introduce a merge node
n
M
into the diagram, draw a connector
from action node
n
0
A
and
n
0
A
to it respectively; and compute the
corresponding state
S
M
of
n
M
;
n
0
A
;
n
0
A
g[f
37.
NS
¼
NS
f
n
M
g
;
38.
else
39.
The conditional branch is failed. Delete the related nodes;
40.
Exit
.
41.
end if
42.
end if
In the reasoning process, once the services mentioned in a user's
preference (i.e.,
w
0
and
w
00
in PPCE) appear, we will examine whether
the truth value of condition formula
Cond
can be acquired and prepare
to introduce a conditional branch structure into the diagram. We need to
check three cases as follows.
