Logical Agents

Outline

Knowledge bases

A simple knowledge-based agent

Wumpus World PEAS description

Wumpus world characterization

Exploring a wumpus world

Exploring a wumpus world

Exploring a wumpus world

Exploring a wumpus world

Exploring a wumpus world

Exploring a wumpus world

Exploring a wumpus world

Exploring a wumpus world

Logic in general

Entailment

Models

Entailment in the wumpus world

Wumpus models

Wumpus models

Wumpus models

Wumpus models

Wumpus models

Inference

Propositional logic: Syntax

Propositional logic: Semantics

Truth tables for connectives

Wumpus world sentences

Truth tables for inference

Inference by enumeration

Logical equivalence

Validity and satisfiability

Proof methods

Resolution

Resolution

Conversion to CNF

Resolution algorithm

Resolution example

Forward and backward chaining

Forward chaining

Forward chaining algorithm

Forward chaining example

Forward chaining example

Forward chaining example

Forward chaining example

Forward chaining example

Forward chaining example

Forward chaining example

Forward chaining example

Proof of completeness

Backward chaining

Backward chaining example

Backward chaining example

Backward chaining example

Backward chaining example

Backward chaining example

Backward chaining example

Backward chaining example

Backward chaining example

Backward chaining example

Backward chaining example

Forward vs. backward chaining

Efficient propositional inference

The DPLL algorithm

The DPLL algorithm

The WalkSAT algorithm

The WalkSAT algorithm

Hard satisfiability problems

Hard satisfiability problems

Hard satisfiability problems

Inference-based agents in the wumpus world

Slide 72

Expressiveness limitation of propositional logic

Summary