KNOWLEDGE BASED AGENTS agents that reason by operating on internal representation. How can we make our AI intelligent/ Logical? Let's ponder on this idea of Logic. Sentence: Representing knowledge. Propositional logic, a staement for / around the world.
Logical Connectives: Not, And, Or, Implication and Biconditional.
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NOT
if P is false then not P is True. and vice versa.
AND
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IMPLICATION
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BICONDITIONAL
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What actually is true in the world? Whether P/ Q is true or false. Hence we bring into the life the notion of a model.
Model
Assignment of a truth value to every propositional symbol ( a "possible world").
Consider to propositional symbols:
P: It is raining
Q: It is a tuesday
{P = true, Q = False}
KNOWLEDGE BASE
A set of sentences known by a knowledge based agent. These are sentences that our AI knows about the world. The AI uses the information to draw conclusions about the world. To draw those conclusions we introduce entailment.
The AI can easily use the deduction based on the first statement to understand the second statement.
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INFERENCE The process of deriving new sentences from old sentences. The ultimate question: can KB entail alpha? Using only the info we know can we conclude that alpha is true. There are couple of algorithms that helps us with this: Model checking.
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-> To determine if KB entails alpha: -> enumerate all possible models -> if KB is true then alpha must also be true ( this forms the foundation of our model checking ).
Using statements and propositional symbols to encode the idea logically through the right representation. This made it possible to convert any problem in the human world and allow the computer to solve it.
