Construct a computer graphic score expert system with PowerBuilder
Wang Jinhui, Li Xingsen, Liu Ziying
1. introduction
The expert system is one of the most active and broadest topics as artificial intelligence applications. It has been successful in various fields, and its main components include knowledge bases, dynamic databases, thrust, interpreters, and interface interfaces. Knowledge Inventory Reservoir About a special knowledge of a certain field, the reinforcing machine is reasonable according to certain strategies, and the dynamic database is used to store the various information required in the system running process. The interpreter is responsible for explaining some of the issues that users need to understand. The interface interface is used for human-computer dialogue.
At present, the construction of the expert system has the following development environment: one is an expert system shell; the second is the expert system development tool; the third is a general artificial intelligence language; four is a general programming language, such as C , Powerbuilder, Visual Basic, etc. .
C is suitable for expert systems that are relatively complicated in the development of a reasoning machine, and an expert system that is relatively simple in reasoning and large dynamic data is large, and the development cycle is long. This type of expert system is relatively simple in reasoning mechanisms and methods, which is especially suitable for use in database development tools. The combination of expert systems and database technology has become an important field of current computer development. In recent years, some people have studied the use of database methods to organize knowledge and have achieved some results. Based on the database-based expert system with a mature database technology as a carrier, use the expert system's ideological method to make reasonable interpretation, make full use of the advantages of the expert system and relational database technology, based on the database, easy to add, modify the knowledge base It is easy to achieve simple learning functions through human-machine dialogue, to establish a knowledge base, boot the reasoning, speeding up search, and make reasoning more simple, efficient. Powerbuilder is one of the most representative database front-end development tools, which has been widely used in the management information system and database application system, and has achieved great success.
We have designed a computer graphic score expert system framework with PowerBuilder 6.5, which can be evaluated, scored, and can be used for all kinds of exams, computer-aided design evaluations, etc., have extensive application prospects. The program has been used in the design of the national registered architect examination. The overall system of the system is shown in Figure 1.
Among them, the score standard acquisition module is used to input score standards through the graphical interface, and the input scoring criteria consistently, redundant checks, and deposits the correct standards in the score standard knowledge base through the Knowledge Base Management Module. The graphical feature extraction module is used to extract the required data from the two-dimensional draft platform, such as the data required in the DXF file of AutoCAD. By calculating, comparing, generating score required, saving files in standard formatting files, used Import the test paper fact library. The division number module is used to develop scores of the scores, and store the score-line grade library after consistency check. Computer score combines the test, score standard knowledge base and score grade library, calculation, comparison, and reasoning, the preliminary conclusion, after the consistency of candidates, the candidates are deposited. The artificial school nuclear module is used for artificial review. The flowchart of the computer score module is shown in Figure 2.
2. Knowledge base, database design
(1) Test consumption fact library
Includes a scivable fact library and an answer library. The scalable fact library structure is score_fact (Fact_ID, Score, Score_Type), used to store the fact that the direct score is used. Where fACT_ID is the fact code, score is the fact that the fact should be score, score_type is a given method. The answering library is used to store the candidates' answer sheet, which has an exam_fact (exam_id, cat_code, item_code, value). Among them, exam_id is the candidate admission ticket number, CAT_CODE is a test code, Item_code is the answer entry code, Value is the value of this entry. (2) Score standard knowledge base
Including rating standard libraries and rules front and rear rear libraries, score standard library structure is score_tree (item_code, item_parent_code, score_flag), which is used to store all of the entry contents of the score standard and its relationship. Among them, item_code is the score standard entry code, Item_name is an entry name, Item_Demand is a specific requirement for this entry, Item_parent_code is the upper layer code code. Score_flag is used to distinguish this entry classification (direct comparison, rule reasoning, function calculations).
The structure of the rule front and rear library is Rule_FACT (Fact_ID, FACT_NAME, ITEM_CODE, USED_BY, DEDUCED_BY, Attribute). It is used to store the premise or conclusions of each rule. Among them, Fact_ID is the fact number, FACT_NAME is the fact name, Item_code is the entry code, using_by uses this fact as the rules, Deduced_by can launch the rules of this fact, attribute, indicate this fact type, target, can deduce fact, known fact Which of them is in.
3. Reasoning machine design
From the scoring standard library, sequentially query according to the examination code, according to the score flag. If the rating marker is "D", you can find the same entry value of Item_code in the real library. Direct comparison, the correct score is obtained. If the score mark is "F", the corresponding parameter code is further queried. From the candidate fact library, the corresponding parameter values will be proposed, and the values of the values and rating standards after the formula are compared to the correct answer in the score standard. If the rating mark is "R", the content of the score fact library is queried, enabling rules reasoning, and the conclusions launched are correct or not. There are two reasonable methods for application rules, and the specific reasoning process is as follows:
The first method is reverse reasoning: (1) Find the corresponding facts F1 in the rule base in the rule base in the rule base, and obtain the maximum possible rule R1 by DEDUCed_by. (2) Looking for R1 in the rule base, take out the first fact in the corresponding premise, if it is a deduction fact, then repeat steps (1), (2) until a corresponding known fact, if All of the facts is successful, otherwise the failure information is recorded, and the next standard is turned.
The second method is a forward reasoning, which is gradually decreasing in a depth priority policy, and is gradually decreasing according to the known USED_BY part until the goal is obtained. If the rule is established, the corresponding score is obtained, otherwise the score is 0, the record failed information, and the result is deposited into the candidate.
Several methods of this program take a long additional short, which can be easily modified, supplemented to the scoring standard library, so that other types of design, examination, etc. can be used to adapt to strong adaptability, fundamentally solve the problem of difficult expert knowledge acquisition. 4. Conclude
Developed a database-based expert system with PowerBuilder, the management is convenient and intuitive, and implements the dynamic management of the rules, solves the problem of difficulties in expert system knowledge, and uses database index technology and filtering mechanism to guide reasoning, making reasoning simpler, efficient . Although the knowledge involved in computer graphics is very complicated, there are still many problems need to be solved, but through the development of the national registered architect exam test score system, it can be seen that the use of PowerBuilder's database-based expert system, time short, effective Fast, high efficiency is a specialized expert system constructor, which enables the field experts to build expert systems in their own fields in the case of fundamental unspeakable engineers.
