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A little bit of review/ wrapup. What are the four elements of consideration when designing rational agents? Remember PEAS? Performance Measure Environment Actuators Sensors. PEAS - Internet news gathering agent. Scans Internet news sources to pick interesting items for its customers
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A little bit of review/wrapup • What are the four elements of consideration when designing rational agents? • Remember PEAS? • Performance Measure • Environment • Actuators • Sensors
PEAS - Internet news gathering agent Scans Internet news sources to pick interesting items for its customers • Performance measure? • Environment? • Actuators? • Sensors?
Environment Types • We often describe the environment based on six attributes. • Fully/partially observable • Deterministic/stochastic • Episodic/sequential • Static/dynamic • Discrete/continuous • Single agent/multiagent
Environment Types • Categorization of environment tasks: • Fully/partially observableextent to which an agent’s sensors give it access to the complete state of the environment • Deterministic/stochasticextent to which the next state of the environment is determined by the current state and the current action
Environment Types • Categorization of environment tasks: • Episodic/sequentialextent to which the agent’s experience is divided into atomic episodes • Static/dynamicextent to which the environment can change while the agent is deliberating
Environment Types • Categorization of environment tasks: • Discrete/continuousextent to which state of the environment, time, percepts and actions of the agent are expressed as a set of discrete values • Single agent/multiagent
Artificial Intelligence in the 21st CenturyS. Lucci / D. Kopec • Chapter 2:Uninformed Search
Contents • 2.0Search in Intelligent Systems • 2.1 State Space Graphs • 2.2 Generate and Test Paradigm • 2.3 Blind Search Algorithms • 2.4 Implementing and Comparing Blind Search Algorithms • Summary
Problem Solving by Searching • “Problem solving agents decide what to do by finding sequences of actions that lead to desirable states.” • Search is a natural part of people’s lives
Remember this Problem? • Three missionaries and three cannibals • Want to cross a river using one canoe. • Canoe can hold up to two people. • Can never be more cannibals than missionaries on either side of the river. • Aim: To get all safely across the river without any missionaries being eaten. • Did you solve it? How????
One Solution • Send over 2 Cannibals • Send one Cannibal back • Send over 2 Cannibals • Send one Cannibal back • Send over 2 Missionaries • Send one Cannibal and one Missionary back • Send over 2 Missionaries • Send one Cannibal back • Send over 2 cannibals • Send one cannibal back • Send over 2 cannibals
How About Another Problem? • Example: Traveling in Romania • On holiday in Romania; currently in Arad.Flight leaves tomorrow from Bucharest
How About Another Problem? • Example: Traveling in Romania • On holiday in Romania; currently in Arad.Flight leaves tomorrow from BucharestFormulate goal: be in BucharestFormulate problem: states: various cities actions: drive between citiesFind solution: sequence of cities, e.g., Arad, Sibiu, Fagaras, Bucharest
Observable?? Deterministic?? Episodic?? Static?? Discrete?? Agents?? Yes Yes Either Yes Yes Either Appropriate environment for Searching Agents
2.1 State Space Graphs • A mathematical structure that helps to formalize the search process • Possible alternative paths leading to a solution can be explored and analyzed • A solution to a problem will correspond to a path through a state space graph