Wikibook - Knowledge Representation

• What is knowledge? Why is it so important to us?
• mental representations of the world, a structured collection of information that can be acquired through learning , perception of reasoning.
• ex. "Watson"the computer playing jeopardy, and beating others... its a computer manipulation of knowledge representation.
• It is so important because it is essential to so many other things we do with our minds.
• Why are categories or concepts so important to knowledge?
• Saving time and effort so we don't have to remember every detail of everything - efficiently and save space.
• Category: a group of something that are labeled with similar properties of and other general information.
• Perhaps the categories and concepts are important for survival, too, so we can know dangerous from not dangerous, and we don't have to dawdle. 
• Concepts can't always be so rigidly defined, because real concepts tend to overlap - hard to figure out, what are the core of the essential features?
• Definitions don't work very well for real concepts (ex. cars)
• This brings about the idea of family resemblance: members of a category resemble each other in several ways.
• Prototype Approach: a kind of mental average
• typicality effect: high-prototypical members are faster recognized as a member of a category, ex. sparrow is more prototypical of a bird than a penguin.
• Exemplar Approach: judging by comparison to examples you have in your mind... can also explain the typciality effect.
• Heirarchical organization of categories.:
• Supordinate level: ex. animal (decrease of information)
• Basic level: ex. dog
• Most common and preferred.
• Subordinate level: ex. Retriever (low gain of information)
• most expert.
• Maybe your base level is higher if you're an expert.