The Comparison Between Forward and Backward Chaining
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International Journal of Machine Learning and Computing, Vol. 5, No. 2, April 2015 The Comparison between Forward and Backward Chaining Ajlan Al-Ajlan system. The comparison will be based on the adequacy of the Abstract—Nowadays, more and more students all over the reasoning strategy, which means to what extent the given world need expert systems, especially in academic sectors. They strategy can be used to represent all knowledge required for need advice in order to be successful in their studies, and this the management expert system. The basic description of an advice must be provided by the academic management. There are two reasoning strategies in expert system, which have educational management expert system is the use of expert become the major practical application of artificial intelligence system techniques in management to be used in the academic research: forward chaining and backward chaining. The first sector. What does academic management mean? In any one starts from the available facts and attempts to draw academic sector there must be co-ordinator who co-ordinates conclusions about the goal. The second strategy starts from specific programmes and should provide suitable advice for expectations of what the goal is, and then attempts to find every student who needs it. The co-ordinator should consider evidence to support these hypotheses. The aim of this paper is to make a comparative study to identify which reasoning various factors before he provides the advice, and neglecting strategy system (forward chaining or backward chaining) is any one of them might affect the advice negatively. This more applicable when making evaluations in expert system will facilitate the task of the co-ordinator, and will management, especially in the academic field. help to provide the best advice for each case. The importance of this study is: 1) no previous work has Index Terms—Artificial intelligence, expert system, forward been done to compare forward-chaining and and backward chaining, state space. backward-chaining in the field of management in the academic sector, 2) to select the reasoning strategy paradigms required for a particular problem, 3) the study will contribute I. INTRODUCTION to the already on-going research on expert systems, namely, In the academic field, some students need the best advice in on managerial expert systems, 4) the research will lay a good order to improve their situation, and this advice must be foundation for other researchers intending to work in this area provided by the academic management. The academic by providing a full picture of expert systems, their management should consider many important factors when components, and related issues and 5) if this project is providing such advise and some of these factors are the mode implemented, it will reduce the time and effort needed by of study (part-time or full-time), is the student working or not, students to meet the programme co-ordinator to obtain advice the number of courses taken last semester, the CGPA of last on a certain problem. semester etc. In addition, as modern society has become more This paper is structured as follows: in the beginning, we specialized, the need to have “expert systems” is increasing present the related studies including a literature review of AI rapidly. These needs are visible in all areas of life [1]. and expert system in Section II and Section III. Section IV These days, humans provide most “expert advice”. They highlights on the GAES. An implementation of GAES using have initiative and intelligence to adapt to a new model the backward and forward-chaining techniques is presented in automatically and made decisions based on new data rapidly. Section IV. An analysis and evaluation of GAES of this paper However, humans also take a long time to learn things and can is presented in Section V. Finally, the conclusion is in Section only perform one complete task at a time. For some of the VI. reasons mentioned above, many companies have attempted to amass and collate the knowledge of experts about a special problem area. Some other reasons are as follows: (1) the II. ARTIFICIAL INTELLIGENCE knowledge of people who have particular expertise can be Artificial Intelligence (AI) began before the arrival of stored before they retire, so the company does not lose their electronics; it began when philosophers and mathematicians knowledge and (2) the implementation of expert systems such as George Boole (rightly regarded as one of the founding lightens the load on specialists. Such systems can be created fathers of computing and information technology to solve routine problems more easily and quickly [2]-[4]. (1815–1864)) and others established the principles, which The aim of this paper is to make a comparative study came to be used as the basis for AI logic. In 1943, AI started between forward-chaining and backward-chaining to select with the beginning of the invention of the computer [5]. which of them is more applicable to the management expert AI is a part of computer science and provides machines with the ability to find the best solution for complex problems Manuscript received August 4, 2014; revised December 8, 2014 This work was supported by the Qassim University. in a more human-like fashion [6], [7]. In other words, AI is Ajlan Al-Ajlan is with the Department of Information System concerned with programming computers to achieve tasks Management, Qassim University, Saudi Arabia (e-mail: which are at present done better by humans, because they [email protected]). DOI: 10.7763/IJMLC.2015.V5.492 106 International Journal of Machine Learning and Computing, Vol. 5, No. 2, April 2015 include much higher mental processes such as memory time. It is a complex type and is not optimal [13], [14], [17]. association, cognitive learning, and critical reasoning. Uniform Cost Search (UCS): According to [3], UCS is Therefore, writing a program to perform a complex similar to BFS, except that it accumulates costs to select the arithmetical calculation would not be seen as an AI action, best node to expand. It stops when a goal is reached and when whereas, writing a program to test a theory would [8], [9]. AI no other node expansion can provide a lesser amount of costly has search strategies that can be divided into two kinds of solution. UCS strategy discovers the solution with the least search as follows [3], [10], [11]: path cost, whereas BFS discovers the goal with the least depth as in Fig. 3 [17], [18]. A. Uniformed Search Strategies (Blind Search) This explores the alternatives and events of a problem space one at a time. It is an algorithm approach and is able to distinguish a goal from other solutions, but the operators must A A A A 1 15 1 15 1 15 15 be available to make decisions about any given goal. There 5 5 5 1 5 B C D B C D B C D B C D are many uninformed search strategies and we will cover 10 10 10 10 5 5 5 some of them, specifically, the three below [12]-[14]: E F F E F E Breadth-First Search (BFS): This begins to search across 1 the first stage of the problem space and it uses a number of F F arbitrary rules, for example, left to right (a search technique Fig. 3. A route finding problem. (1) The state space, showing the cost of each that looks for a solution along all of the nodes on one stage of operator. (2) Progression of search. a problem space before considering nodes at the next lower stage). If it cannot find any solution within this stage, it will B. Informed Search Strategies (Heuristic Search) drop down to the next stage and search in the same way as in In Ref. [18], heuristic search was defined as “the study of Fig. 1. It will always discover the most direct way in first, and the methods and rules of discovering and invention”. It it guarantees a solution. Nevertheless, BFS is an inflexible involves trying all possible search paths to reach the nearer algorithm that blindly types the problem space looking for a goal. goal. It is easy to miss a solution [14]-[16]. Best-First Search (BeFS): It guides the search towards the A Level- 0 solution nodes of the problem space. It should be understood B C Level -1 that the word "best" may not be close to the interpretation of the designer and it usually boils down to selecting the most A 8 C E B A D Level -2 efficacious way to meet the needs of the problem. BeFS is informed and it uses knowledge to guide the search to know H I 7 F Level -3 where best to begin and how best to continue in search of a goal [14], [19]. 6 G I J E H L Level -4 Hill Climbing Search (HCS): This is a kind of DFS and always moves towards the goal. The solution space in this 8 K I I M 1 6 Level -5 search is explored in DFS, following the path that appears to Fig. 1. Breadth-first search in graduate admission expert system. shorten the remaining distance to the conclusion. It uses heuristics to find which direction will take it closest to the goal. However, the constraint of this search is that if we arrive Depth 0 A at a dead end, we will not be able to go backward [20]. Depth 1 A* Search: A search technique that finds minimal cost B C solutions, and is also directed towards goal states, is called an Depth 2 A* (A-star) search.