11 6024 Dalian, China
DKBM: MBMS DBMS
Figure 2:
Parallel to the main stream of decision support process there exists a meta-decision- making advisory process shown on the screen to assist the user, to let him (or her) know where he (or she) is and where he should go.
The meta-decision-making advisory subsystem has its most parts of rule-based. But there are some fuzzy operations used.
Suppose I-space of decision situation P-space of decision problem S-space of solution
The structured problem p E P may be solved by creation of mapping g :
For the semistructured and unstructured problems, P E P cannot be given directly and immediately, only i E I is know. The decision corresponds to create a mapping h:
But in real cases, h also cannot be given immediately. We must firstly construct the mapping relation j:
j : I + P then we have
h = g * j
and j is just the problem-generation process. The construction o f f is as follows. Firstly, we construct
j * : I + A
A is space spanned by m critical factors, characterizing the situation. Then another mapping
f 3 : E + P
is also constructed. E is space of attributes of a given problem. According to experiences, f, and f3 may be created without too much difficulties.
The most crucial task is to create f2
f2 may be ruled-based, but in most cases we may construct a fuzzy map according to domain knowledge and experiences of decision analysis.
Recently, we have found artificial neural network is also powerful for this purpose.
The knowledge base is distributed because we apply the knowledge engineering ap- proach at three levels:
The upper level for guidance of decision process
The intermediate level for model-generation and "what if' analysis The lower level for interpretation of interim and final results
For the convinience of calling the rules and reasoning, rule-based modules are distributed in several subsystems.
Blackboard method is adopted for the scheduling
In the model base, problem-specific models can be generated on the base of user's specifi- cation and in an Entity-Relation-problem framework. Besides the generated model sets.
There are also some standard solvers (For LP, ILP, GP, etc) and analytic modules (AHP, etc).
User-friendly graphical interface is an important part of the whole system. Especially for those decision makers who are not computer-specialist, they can get more information from charts, diagrams, curves and maps than ordinary tables and texts. Top leaders have no much time to watch the data line by line, but the colorful graphs especially the sharp-contrasted diagrams draw their attention at once and they can find the key issues immediately. In China, the screen display must be in Chinese mostly for the convinience of users who do not understand English. But the display of Chinese characters is a time- consuming task and the number of lines is also quite restricted. The graphical display may partly remedy it.
4 System integration
The system integration must be realized at different levels. At conceptional level, we must has a comprehensive system approach. In our system the decision-process orienta- tion and meta-decision-making guidance are the main principles. At the logic level, the
YANG SUPERIOR
Figure 3:
quantitative models and rule sets for qualitative analysis must be able to couple together according to a problem-specific sequence. The most crucial problems are happened at im-
.
plementation level. Firstly a consistent data base must be built up for different modules.At the prototyping stage, redundancy may be unavoidable, but the consistency of data is most important first of all. Data must be easily transmitted between different kinds of modules. The style of man-machine dialog must also be consistent and suitable for user's appetite. The software organization must fulfill the requirement of dynamic scheduling according t o the demand of decision process. In order t o overcome the difficulties of the coupling of different programming languages, we use the language C as the unique host language.
In order t o overcome the restriction of area of screen display (especially for Chinese character display), we use the window technique a t different levels and procedures.
Our experiences of implementation of P D S S on microcomputers over three years show there are bright perspectives for the application of these system t o organizations of different levels, especially to medium and small corporations.
The synergistic operation of "soft technology" (including the human intuition, experi- ence as well inspiration and their implementation such as knowledge engineering approach, fuzzy reasoning, etc) with "hard technology" (including numerical and logical analysis in its strict sense) recall t o us the ancient Chinese Philosophical principle "In-Yang" in the classical book "I-Ching". "In" means flexibility, mildness and adaptability. "Yang"
means strength, rigidity and exactness. The whole decision process, like the world, is a harmonious complexity of "In-Yang". Moreover we have mentioned in the principle of
"I-Ching", there is a further expression of the holistic system as Fig. 3. In the center between "In" and "Yang", there is a "superior". In our understanding, it is a ruling part of whole system. For the 13DSS, this part is just the meta-decision-making module.
References
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