16 April 2011 Alan, Edison, etc, Saturday.

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Noel Greer
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1 16 April 2011 Alan, Edison, etc, Saturday.

2 Knowledge, Planning and Robotics 1. Knowledge 2. Types of knowledge 3. Representation of knowledge 4. Planning 5. Knowledge for planning 6. Planning in robotics 7. Logic in robot planning and behavior

3 Knowledge Representation 1. Representational adequacy 1. declarative, procedural 2. Inferential adequacy 1. manipulate knowledge 2. incorporate new knowledge

4 Types of Knowledge 1. Simple facts 2. Complex organized knowledge 3. procedure - how to knowledge 4. meta-knowledge

5 Semantic Data Models High level model of model Model of conceptual model Not tied to implementation concerns Focus on expressiveness simplicity concise formality

6 Semantic Nets Nodes represent Objects Links or Arcs represent Relationships instance of - set membership is a - inheritance has a - attribute descriptors part of - aggregation

7 Is a Has a Part-of Instance of

8 Advantages Semantic Nets Disadvantages Flexible easy to understand support inheritance natural way to represent knowledge Hard to deal with exceptions procedural knowledge difficult to represent no standards for defining nodes or relationships

9 Classes, Objects, Attributes, Values - Object Orientation Classes describe common properties of objects Objects may be physical or conceptual Attributes are characteristics of objects Values are specific measures of Attributes for specific instances

10 Classes Specify common properties of instances support hierarchical classification superclass / subclass subclass may be more refined version each subclass inherits operations and attributes of its ancestors subclass may have its own operations and attributes

11 Objects or Instances Refers to things identified in model of conceptual model may be tangible (equipment, part, orders, squashed bananas) may be mental constructs

12 Class vs instances instances

13 Inheritance is sharing attributes and behaviors within a class of objects Inheritance customer Person Sales Person Employee Manager Sale Manager

14 Encapsulation Attributes and behaviors (methods) integrated with the classes and objects Attributes: size, location, appearance

15 Polymorphism Each object responds in its unique way to messages When changed method When needed method

16 Object-Orientation Tool for managing complexity 1. emphasis on object structure 2. specify what is 3. mapped directly from semantic net

17 Rule Representations Rules are called productions Rule have two parts condition part, premise -> IF action part,conclusion-> THEN The action can: add a fact to the knowledge base, start a procedure or display a screen

18 Rules represent knowledge Apply O-A-V framework (object-attributevalue) IF air vehicle is a plane AND plane maximum altitude is AND plane manufacturer is Boeing THEN ASK Flight Display 15

19 Representing knowledge Abstracting with rules translate quantitative to qualitative define technical terms support generalized reasoning make rules for user easy to understand help user follow decision logic

20 Rule for understanding Quantitative to Qualitative qualitative language is easier to understand interpretation of numerical data make user feel comfortable with decision logic If temperature > 200 and humidity is 85% then machine is slightly overheated

21 Definitional Rules Help communicate and train users Help user understand vocabulary Promotes common agreement on terms for expert, user and knowledge engineer IF you want more than one source file of classes THEN use package keyword

22 Rules support Generalizations Allow reasoning with from specialization to generalizations Support classification of objects at higher levels Support refinements

23 Surface Knowledge 1. Hard to understand 2. Difficult to learn reasoning strategies 3. hard to update and expand knowledge base If pump operation temperature is over 300 AND water mixture ph > 5.2 THEN replace pump bearing and oil

24 Hierarchical Classification Abstraction draws out important aspects Feature abstractions Solution abstractions Heuristic Match Features generalize refine Recommendations

25 Deep knowledge Lubrication defect Is a Poor Oil Viscosity causes Hot Pump temperature is over 300 causes Low Temp water mixture ph > 5.2

26 Reasoning at higher level Lubrication defect requires Maintenance Replace bearing and oil Fix heat damage Remedy Type of

27 Advantages Rules Disadvantages Modular style - easy to add, update and delete natural for many problem domains uncertain knowledge may be represented May be difficult to understand may demonstrate unpredictable behavior extra effort required to representing structural knowledge

28 Predicate Logic Programming by description describe the problem s facts built in inference engine combines and uses facts and rules to make inferences

29 Prolog Programming Declaring facts about objects and their relationships -> likes (john,mary) Defining rules about objects and relationships Asking Questions about objects sister-of(x,y) :- female(x), parents(x,m,f), parent(y,m,f)

30 Frames Similar to objects helps organize entities packages operations (demons) easy to modify extensible through inheritance

31 Mammal Frame Slot Values Default Demons Skin Birth Fur Live Legs 4 Weight Compute demon

32 Frame - natural representation Can accommodate a taxonomy of knowledge contains defaults expectations represent procedural and declarative knowledge

33 Facets - properties of slots Facets Inference Value Prompt Exhaustive Search Order When Changed When Needed Default Init Reinit Conf Expand Query From Unknown

Object-based representation. Objects

Object-based representation. Objects Object-based representation Luger, Part III, 6.0, 6.1, 6.2.2-6.2.4, 6.4 (skim) Objects Two basic forms of Structured Objects Semantic Nets Frames Semantic Nets (Associative Nets) Components Nodes - represent