10/3/2010 Where are we? Intelligent Systems # Title 1 Introduction 2 Propositional Logic 3 Predicate Logic 4 Reasoning 5 Search Methods 6 CommonKADS Introduction 7 Problem-Solving Methods 8 Planning 9 Software Agents 10 Rule Learning Dr. Anna Fensel 11 Inductive Logic Programming 12 Formal Concept Analysis 13 Neural Networks 14 Semantic Web and Services © Copyright 2010 Dieter Fensel, Tobias Bürger and Ioan Toma 1 2 Overview Examination • Course home page: http://www.sti-innsbruck.at/teaching/course- schedule/ws201011/details/?title=intelligente-systeme (schedule, lecture notes, exercises, etc.) • Exam grade: • Textbooks: score grade – G. Görz, C.-R. Rollinger, J. Schnee- 75-100 1 berger (Hrsg.) “Handbuch der künstlichen Intelligenz” Oldenbourg 65-74.9 2 Verlag, 2003, Fourth edition 55-64.9 3 – G. Luger “Artificial Intelligence – Structures and Strategies for Complex Problem Solving” Addision- 45-54.9 4 Wesley, 2005, Fifth edition 0-44.9 5 • Lecturer(s): Dr. Anna Fensel ([email protected]) and Dr. Ioan Toma ([email protected]) • Tutor(s): Daniel Winkler ([email protected]). • Lectures every week and Tutorials every two weeks • Attendance of the tutorials is obligatory! 3 4 1 10/3/2010 Overview of the course: What is the course about? Outline 1. Introduction • Motivation 2. Propositional logic – What is “Intelligence”? 3. Predicate logic – What is “Artificial Intelligence” (AI)? 4. Reasoning – Strong AI vs. Weak AI 5. Search methods • Technical Solution 6. CommonKADS – Symbolic AI vs. Subsymbolic AI 7. Problem-solving methods – KldKnowledge-bdbased sys tems 8. Planning • Popular AI systems 9. Software Agents • Subdomains of AI 10. Rule learning • Some relevant people in AI 11. Inductive logic programming • Summary 12. Formal concept analysis 13. Neural networks 14. Semantic Web and Services 5 6 6 What is “Intelligence”? • "Intelligence denotes the ability of an individual to adapt his thinking to new demands; it is the common mental adaptability to new tasks and conditions of life" (William Stern, 1912) • Being "intelligent" means to be able to cognitively grasp phenomena, being able to judge, to trade of between different possibilities, or to be able to learn. • An important aspect of "Intelligence" is the way and efficiency how humans are able to adapt to their environment or assimilate their environment for solving problems. Introduction to Artificial Intelligence • Intelligence manifests itself in logical thinking, computations, the memory capabilities of the brain, through the application of words and language MOTIVATION rules or through the recognition of things and events. • The combination of information, creativity, and new problem solutions is crucial for acting "intelligent". 7 7 8 2 10/3/2010 Testing “Intelligence” with the Turing Test Testing “Intelligence” with the Turing Test (1) • Turing test is a proposal to test a machine’s ability to • Turing test proceeds as follows: demonstrate “intelligence” – A human judge C engages in a natural language conversation with one human B and one machine A, each of which tries to appear human. – All participants are placed in isolated locations. – If the judge C cannot reliably tell the machine A from the human B, the machine is said to have passed the test. – In order to test the machine's intelligence rather than its ability to render words into audio, the conversation is limited to a text-only channel such as a computer keyboard or screen • Turing test is an operational test for intelligent behaviour. For more details see [2]. Source: http://en.wikipedia.org/wiki/Turing_test 9 10 “Chinese Room” “Chinese Room” (1) • The “Chinese room” experiment • The “Chinese room” experiment developed by John proceeds as follows: Searle in 1980 attempts to show that a symbol- – Searle, a human, who does not processing machine like a computer can never be knows Chinese, is locked in a properly described as having a ”mind” or room with an enormous batch of Chinese script. “understandingg,”, reg ardless of how intellig ently it may – Slips o f paper with still more behave. Chinese script come through a slot in the wall. – Searle has been given a set of • With the “Chinese room” John Searle argues that it is rules in English for correlating the possible to pass the Turing Test, yet not (really) think. Chinese script coming through with the batches of script already in the room. Source: http://en.wikipedia.org/wiki/Chinese_room 11 12 3 10/3/2010 “Chinese Room” (2) “Chinese Room” (3) – Searle is instructed to push back through the slot the Chinese • The result: script with which the scripts coming in through the slot are – It seems clear that Searle nevertheless does not understand the correlated according to the rules. questions or the answers – Searle identifies the scripts coming in and going out on the basis – But Searle is behaving just a computer does, “performing of their shapes alone. He does not speak Chinese, he does not computational operations on formally specified elements” understand them – The scripts going in are called ‘the questions’, the scripts coming out are ‘the answers’, and the rules that Searle follows is ‘the • Hence, manipulating formal symbols, which is just what a program’. computer running a program does, is not sufficient for – Suppose also that the set of rules, the program is so good and understanding or thinking Searle gets so good at following it that Searle’s answers are indistinguishable from those of a native Chinese speaker. 13 14 What is “Artificial Intelligence”? Early developments of Artificial Intelligence • Many definitions exist, among them: • Two main aspects begin to manifest in the early days of AI – “The study of the computations that make it possible to perceive, 1. Cognitive modelling, i.e., the simulation of cognitive processes through reason, and act” (Winston, 1992) information processing models – “A field of study that seeks to explain and emulate [human] intelligent 2. The construction of “intelligent systems” that make certain aspects of behaviour in terms of computational processes” (Schalkoff, 1990) human cognition and reasoning available. • It is an interdisciplinary field that is based on results from philosphy, psychlhology, lingu itiistics, or bra in sc iences • Difference to “traditional” computer science: Emphasis on cognition, reasoning, and acting • Generative theory of intelligence: – Intelligence emerges from the orchestration of multiple processes – Process models of intelligent behaviour can be investigated and simulated on machines 15 16 4 10/3/2010 Strong AI vs. Weak AI • Strong AI – “An artificial intelligence system can think and have a mind. “ (John Searle 1986) – “Machine intelligence with the full range of human intelligence” (Kurzweil 2005) – AI that matches or exceeds human intelligence. – Intelligence can be reduced to information processing. – “Science Fiction AI” Symbolic vs. Subsymbolic AI; Knowledge-based Systems • Weak AI – Intelligence can partially be mapped to computational processes. TECHNICAL SOLUTIONS – Intelligence is information processing – Intelligence can be simulated 17 18 18 Information Processing and symbolic representation • Research on Information Processing in AI by – Exact formulisations. – Exemplary realisation via implementations. • Core aspect: Representation and processing of symbols as a foundation of internal processes. SYMBOLIC AI vs. SUBSYMBOLIC AI 19 19 20 5 10/3/2010 Symbolic AI The “(General) Intelligent Agent” • Symbols are naming objects which provide access to meaning • Core paradigm of symbolic AI is the “Intelligent Agent” [4]: (Newell, 1958) – has a memory and the capability to act in his world based on it. • “Spoken words are the symbols of mental experience, and written – has sensors to perceive information from his environment. words are the symbols of spoken words.” (Aristotle) [3] – has actuators to influence the external world. • Mental abilities of humans can be inspected on a symbolic level – has the capability to probe actions. By that he is able to choose the best independent of neuronal architectures or processes. possible action . • Subject of Symbolic AI is thus the meaning of processes (or their – has internal memory for methods and the exploration of the world is symbolic representations respectively). guided by knowledge kept in it. • Symbolic AI aims to imitate intelligence via formal models. • Main persons behind symbolic AI are: Simon, Newell, Minsky Image from Padgham/Winikoff “Developing Intelligent Agents (Wiley 2004) 21 22 Subymbolic AI • Subsymbolic AI (SSAI) aims to model intelligence empirically. • SSAI was inspired by biological systems: A model which imitates neural nets in the brain is the basis for the creation of artificial intelligence. • Neural nets consist of a network of neurons which have weighted connections with each other. • Early work by Rosenblatt (1962): the “Perceptron” [6] • Advantages of artificial neuronal nets: – Distributed representation KNOWLEDGE-BASED SYSTEMS – Representation and processing of fuzziness – Highly parallel and distributed action – Speed and fault-tolerance Image: http://www.neuronalesnetz.de 23 24 24 6 10/3/2010 Development 1. General Problem Solver 1. General Problem Solver • The General Problem Solver (GPS) is a universal problem solving approach. 2. Knowledge-is-power hypothesis • GPS is the first approach that makes the distinction 3. Knowledge levels between knowledge of problems domains and how to 3a. Newell’ s 3 levels of knowledge solve problems 3b. Brachman’s 5 levels of knowledge • GPS