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Questions and Answers
What role does knowledge play in an intelligent system?
What role does knowledge play in an intelligent system?
Which representation uses logical symbols to express relationships?
Which representation uses logical symbols to express relationships?
How is knowledge defined in the provided content?
How is knowledge defined in the provided content?
What is a proposition in the context of propositional logic?
What is a proposition in the context of propositional logic?
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Which logical operator represents the idea of 'if ... then ...'?
Which logical operator represents the idea of 'if ... then ...'?
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What does the expression P Q represent in propositional logic?
What does the expression P Q represent in propositional logic?
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Which of the following is a limitation of propositional logic?
Which of the following is a limitation of propositional logic?
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In first order logic, what is the role of predicates?
In first order logic, what is the role of predicates?
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What does the expression X.likes(X, apples) indicate?
What does the expression X.likes(X, apples) indicate?
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Why might propositional logic be insufficient for expressing certain statements?
Why might propositional logic be insufficient for expressing certain statements?
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Study Notes
Knowledge Representation
- Knowledge representation stores and processes knowledge effectively.
- Knowledge is crucial for intelligent systems to make informed decisions.
- Knowledge bases (KBs) contain facts about the world.
Types of Knowledge Representation
- Data: Primitive, verifiable facts, often changing and voluminous.
- Information: Interpreted data.
- Knowledge: Relationships between datasets (information), used for deduction. Generalizes data and incorporates information about the behavior of world models.
General Knowledge Representation Schemas
- Logic-Based Representation: Uses first-order predicate logic (FOL).
- Procedural Representation: Employs production rules.
- Network Representation: Includes semantic networks and conceptual graphs.
- Structural Representation: Utilizes scripts, frames, and objects.
Logic Based Representation
Propositional Logic
- Represents knowledge as propositions, statements that are either true or false.
- Uses logical operators:
- Conjunction (and) ()
- Disjunction (or) ()
- Negation (not) ()
- Implication ( )
- Equivalence ().
Propositional Logic Limitations
- Only handles true or false values.
- Represents entire propositions as single symbols, limiting the representation of objects with properties.
- Difficulty in adapting to knowledge base modifications.
- Lack of expressiveness, requiring multiple propositions to define complex concepts.
First Order Logic (FOL)
- Extends propositional logic, incorporating objects, properties, and relations.
- Allows for beliefs about truth, falsehood, or uncertainty of relations.
- Uses constructs:
- Constants: Represents objects (e.g., john, apples)
- Predicates: Represents properties and relations (e.g., likes(john, apples))
- Functions: Transform objects (e.g., likes(john, fruit_of(apple_tree)))
- Variables: Represents any object (e.g., likes(X, apples))
- Quantifiers: Qualify variable values:
- Universal quantifier (): True for all objects (e.g., X.likes(X, apples))
- Existential quantifier (): True for at least one object (e.g., X.likes(X, apples))
First Order Logic and Prolog
- Prolog is a declarative programming tool for building artificial intelligence programs based on FOL.
- Prolog's foundation is first-order logic syntax, consisting of facts and rules.
Procedural Representation
Production Rules
- Represent knowledge as sets of “if condition then action” pairs.
- Follow a match-resolve-act cycle:
- Match: Checks if rule conditions hold.
- Resolve: Chooses a rule from the set of firing rules (conflict resolution).
- Act: Executes the chosen rule's action.
- Rules can write knowledge to working memory, potentially triggering other rules.
Network Representation
Semantic Networks
- Depict objects as nodes in a hierarchical network of relationships.
- Allow for inheritance of properties, analogous to object-oriented programming (OOP).
- Minimize redundancy by representing objects with the least number of nodes and links.
Structural Representation
Frame Representations
- Use a data structure, known as a frame, to represent knowledge about specific objects or concepts.
- Developed by Marvin Minsky in the 1970s for use in frame-based expert systems.
- Offer more intuitive value support compared to semantic networks, with slots containing constraints for acceptable values.
- Can be easily implemented using OOP techniques.
- Enable straightforward control of inheritance.
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Description
This quiz explores the essential concepts of knowledge representation, including different types such as data, information, and knowledge. It also covers various representation schemas like logic-based and procedural representations, essential for intelligent systems development.
