Introduction to Knowledge Engineering.ppt

1、Introduction to Knowledge Engineering,What is Knowledge Engineering? History & Terminology,Introduction,2,Data, information & knowledge,Data “raw signals” . . . - - - . . . Information meaning attached to data S O S Knowledge attach purpose and competence to information potential to generate action

2、emergency alert start rescue operation,Introduction,3,Knowledge engineering,process of eliciting, structuring, formalizing, operationalizing information and knowledge involved in a knowledge-intensive problem domain, in order to construct a program that can perform a difficult task adequately,Introd

3、uction,4,Problems in knowledge engineering,complex information and knowledge is difficult to observe experts and other sources differ multiple representations: textbooks graphical representations heuristics skills,Introduction,5,Importance of proper knowledge engineering,Knowledge is valuable and of

4、ten outlives a particular implementation knowledge management Errors in a knowledge-base can cause serious problems Heavy demands on extendibility and maintenance changes over time,Introduction,6,A Short History of Knowledge Systems,Introduction,7,First generation “Expert” Systems,shallow knowledge

5、base single reasoning principle uniform representation limited explanation capabilities,Introduction,8,Transfer View of KE,Extracting knowledge from a human expert “mining the jewels in the experts head” Transferring this knowledge into KS. expert is asked what rules are applicable translation of na

6、tural language into rule format,Introduction,9,Problems with transfer view,The knowledge providers, the knowledge engineer and the knowledge-system developer should share a common view on the problem solving process and a common vocabularyin order to make knowledge transfer a viable way of knowledge

7、 engineering,Introduction,10,Rapid Prototyping,Positive focuses elicitation and interpretation motivates the expert (convinces management) Negative large gap between verbal data and implementation architecture constrains the analysis hence: distorted model difficult to throw away,Introduction,11,Met

8、hodological pyramid,Introduction,12,World view: Model-Based KE,The knowledge-engineering space of choices and tools can to some extent be controlled by the introduction of a number of models Each model emphasizes certain aspects of the system to be built and abstracts from others. Models provide a d

9、ecomposition of knowledge-engineering tasks: while building one model, the knowledge engineer can temporarily neglect certain other aspects.,Introduction,13,CommonKADS principles,Knowledge engineering is not some kind of mining from the experts head, but consists of constructing different aspect mod

10、els of human knowledge The knowledge-level principle: in knowledge modeling, first concentrate on the conceptual structure of knowledge, and leave the programming details for later Knowledge has a stable internal structure that is analyzable by distinguishing specific knowledge types and roles.,Intr

11、oduction,14,CommonKADS theory,KBS construction entails the construction of a number of models that together constitute part of the product delivered by the project. Supplies the KBS developer with a set of model templates. This template structure can be configured, refined and filled during project

12、work. The number and level of elaboration of models depends on the specific project context.,Introduction,15,CommonKADS Model Set,Introduction,16,Model Set Overview (1),Organization model supports analysis of an organization, Goal: discover problems, opportunities and possible impacts of KBS develop

13、ment. Task model describes tasks that are performed or will be performed in the organizational environment Agent model describes capabilities, norms, preferences and permissions of agents (agent = executor of task).,Introduction,17,Model Set Overview (2),Knowledge model gives an implementation-indep

14、endent description of knowledge involved in a task. Communication model models the communicative transactions between agents. Design model describes the structure of the system that needs to be constructed.,Introduction,18,Principles of the Model Set,Divide and conquer. Configuration of an adequate

15、model set for a specific application. Models evolve through well defined states. The model set supports project management. Model development is driven by project objectives and risk. Models can be developed in parallel.,Introduction,19,Models exist in various forms,Model template predefined, fixed

16、structure, can be configured Model instance objects manipulated during a project. Model versions versions of a model instance can exist. Multiple model instances separate instances can be developed example: current and future organization,Introduction,20,The Product,Instantiated models represent the

17、 important aspects of the environment and the delivered knowledge based system. Additional documentation information not represented in the filled model templates (e.g. project management information) Software,Introduction,21,Roles in knowledge-system development,knowledge provider knowledge enginee

18、r/analyst knowledge system developer knowledge user project manager knowledge managerN.B. many-to-many relations between roles and people,Introduction,22,Knowledge provider/specialist,“traditional” expert person with extensive experience in an application domain can provide also plan for domain fami

19、liarization “where would you advise a beginner to start?” inter-provider differences are common need to assure cooperatio,Introduction,23,Knowledge engineer,specific kind of system analyst should avoid becoming an “expert“ plays a liaison function between application domain and system,Introduction,2

20、4,Knowledge-system developer,person that implements a knowledge system on a particular target platform needs to have general design/implementation expertise needs to understand knowledge analysis but only on the “use”-level role is often played by knowledge engineer,Introduction,25,Knowledge user,Pr

21、imary users interact with the prospective system Secondary users are affected indirectly by the system Level of skill/knowledge is important factor May need extensive interacting facilities explanation His/her work is often affected by the system consider attitude / active tole,Introduction,26,Proje

22、ct manager,responsible for planning, scheduling and monitoring development work liaises with client typically medium-size projects (4-6 people) profits from structured approach,Introduction,27,Knowledge manager,background role monitors organizational purpose of system(s) developed in a project knowl

23、edge assets developed/refined initiates (follow-up) projects should play key role in reuse may help in setting up the right project team,Introduction,28,Roles in knowledge-system development,Introduction,29,Terminology,Domain some area of interest banking, food industry, photocopiers, car manufactur

24、ing Task something that needs to be done by an agent monitor a process; create a plan; analyze deviant behavior Agent the executor of a task in a domain typically either a human or some software system,Introduction,30,Terminology,Application The context provided by the combination of a task and a do

25、main in which this task is carried out by agents Application domain The particular area of interest involved in an application Application task The (top-level) task that needs to be performed in a certain application,Introduction,31,Terminology,knowledge system (KS) system that solves a real-life problem using knowledge about the application domain and the application task expert system knowledge system that solves a problem which requires a considerable amount of expertise, when solved by humans.,