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<!DOCTYPE html>
<html>
<title>Agents and environments</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://www.w3schools.cn/w3css/4/w3.css">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>search</title>
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<body>
<!-- Sidebar -->
<div class="w3-sidebar w3-light-grey w3-bar-block" style="width:15%">
<a href="./index.html"><h3 class="w3-bar-item">Artificial Intelligence</h3></a>
<a href="./lec2.html" class="w3-bar-item w3-button w3-large">Agents and environments</a>
<ul>
<li><a href="#title-1-1" class="w3-bar-item w3-button">Agents and environments</a></li>
<li><a href="#title-1-2" class="w3-bar-item w3-button">Rationality</a></li>
<li><a href="#title-1-3"class="w3-bar-item w3-button">PEAS</a></li>
<li><a href="#title-1-4" class="w3-bar-item w3-button">Environment types</a></li>
<li><a href="#title-1-5" class="w3-bar-item w3-button">Agent types</a></li>
<li><a href="#title-1-6" class="w3-bar-item w3-button">Summary</a></li>
</ul>
<a href="./lec3.html" class="w3-bar-item w3-button w3-large">Uninformed Search</a>
<a href="./lec4.html" class="w3-bar-item w3-button w3-large">Informed Search</a>
<a href="./lec5.html" class="w3-bar-item w3-button w3-large">Local search</a>
<a href="./lec6.html" class="w3-bar-item w3-button w3-large">Adversarial Search</a>
<a href="./lec7.html" class="w3-bar-item w3-button w3-large">Expectimax Search</a>
<a href="./lec8.html" class="w3-bar-item w3-button w3-large">Markov Decision Process</a>
</div>
<!-- Page Content -->
<div style="margin-left:15%">
<div class="w3-container w3-teal">
<h1 id="title-1-1">Agents and environments</h1>
</div>
<div class="w3-container">
<br>
<img src="./image/lec2_2.png" alt="" style="width:50%;position: relative; left: 280px;">
<font size="5">
<ul>
<font size="5">
<li>An agent perceives its environment through sensors and acts upon it through actuators (or effectors, depending on whom you ask)</li>
<li>Are humans agents?</li>
<li>Are pocket calculators agents?</li>
<li>AI is more interested in agents with large computational resources and environments that require nontrivial decision making</li>
<br>
</font>
</ul>
</font>
</div>
<div class="w3-container w3-teal">
<h1 id="title-1-2">Rationality</h1>
</div>
<div class="w3-container">
<br>
<font size="5">
<ul>
<font size="5">
<li>Are rational agents?</li>
<li>Do rational agents explore and learn?</li>
<li>Do rational agents make mistakes?</li>
<li>Are rational agents autonomous (i.e., transcend initial program)?</li>
<br>
</font>
</ul>
</font>
</div>
<div class="w3-container w3-teal">
<h1 id="title-1-3">PEAS (Performance measure, Environment, Actuators, Sensors)</h1>
</div>
<br>
<h2 style="position: relative;">
<font size="6">A human agent in Pacman</font>
<br>
<video loop="loop" controls="controls" poster="" style="width:70%; position: relative; left:200px">
<source src="./video/lec2-1.mp4" type="video/mp4"></source>
</video>
</h2>
<br>
<h2 style="position: relative;">
<font size="6">The task environment - PEAS</font> <img src="./image/lec2_3.jpg" alt="" style="width:35%; float:right; margin: 30px;">
</h2>
<font size="5">
<ul>
<font size="5">
<li>Performance measure</li>
<p>-1 per step; + 10 food; +500 win; -500 die;+200 hit scared ghost</p>
<li>Environment</li>
<p>Pacman dynamics (incl ghost behavior)</p>
<li>Actuators</li>
<p>Left Right Up Down</p>
<li>Sensors</li>
<p>Entire state is visible (except power pellet duration)</p>
<br>
</font>
</ul>
</font>
<br>
<h2 style="position: relative;">
<font size="6">PEAS: Automated taxi</font> <img src="./image/lec2_4.png" alt="" style="width:25%;position: relative; float:right; margin: 60px">
</h2>
<font size="5">
<ul>
<font size="5">
<li>Performance measure</li>
<p>Income, happy customer, vehicle costs, fines, insurance premiums</p>
<li>Environment</li>
<p>US streets, other drivers, customers, weather, police…</p>
<li>Actuators</li>
<p>Steering, brake, gas, display/speaker</p>
<li>Sensors</li>
<p>Camera, radar, accelerometer, engine sensors, microphone, GPS</p>
<br>
</font>
</ul>
<h2 style="position: relative;">
<br>
<br>
<br>
<font size="6">PEAS: Medical diagnosis system</font>
</h2>
<font size="5">
<ul><img src="./image/lec2_5.png" alt="" style="width:40%;position: relative; left: 280px;">
<font size="5">
<li>Performance measure</li>
<p>Patient health, cost, reputation</p>
<li>Environment</li>
<p>Patients, medical staff, insurers, courts</p>
<li>Actuators</li>
<p>Screen display, email</p>
<li>Sensors</li>
<p>Keyboard/mouse</p>
<br>
</font>
</ul>
<div class="w3-container w3-teal">
<h1 id="title-1-4">Environment types</h1>
</div>
<br>
<div class="w3-container">
<img src="./image/lec2_6.png" alt="" style="width:50%;position: relative; left: 280px">
<br>
<br>
</div>
<br>
<div class="w3-container w3-teal">
<h1 id="title-1-5">Agent types</h1>
</div>
<br>
<div class="w3-container">
<h2 style="position: relative;">
<font size="6">Agent design</font>
</h2>
<p>The environment type largely determines the agent design</p>
<ul>
<li>Partially observable => agent requires memory (internal state)</li>
<li>Stochastic => agent may have to prepare for contingencies </li>
<li>Multi-agent => agent may need to behave randomly</li>
<li>Static => agent has time to compute a rational decision</li>
<li>Continuous time => continuously operating controller</li>
<li>Unknown physics => need for exploration</li>
<li>Unknown perf. measure => observe/interact with human principal</li>
<br>
</ul>
<h2 style="position: relative;">
<font size="6">Agent types</font>
</h2>
<p>In order of increasing generality and complexity</p>
<ul>
<li>Simple reflex agents （单反射性智能主体）</li>
<img src="./image/lec2_7.png" alt="" style="width:30%;position: relative; left: 280px;">
<br>
<li>Model-based reflex agents（基于模型的反射性智能主体）</li>
<img src="./image/lec2_8.png" alt="" style="width:30%;position: relative; left: 280px;">
<br>
<li>Goal-based agents （基于目标的智能主体）</li>
<img src="./image/lec2_9.png" alt="" style="width:30%;position: relative; left: 280px;">
<br>
<li>Utility-based agents （基于效用的智能主体）</li>
<img src="./image/lec2_10.png" alt="" style="width:30%;position: relative; left: 280px;">
<br>
</ul>
<div class="w3-container w3-teal">
<h1 id="title-1-6">Summary</h1>
</div>
<ul>
<li>An agent interacts with an environment through sensors and actuators</li>
<li>The agent function, implemented by an agent program running on a machine, describes what the agent does in all circumstances </li>
<li>Rational agents choose actions that maximize their expected utility</li>
<li>PEAS descriptions define task environments; precise PEAS specifications are essential and strongly influence agent designs </li>
<li>More difficult environments require more complex agent designs and more sophisticated representations</li>
</ul>
</div>
<br>
</div>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
</html>