Answers.Body: <p>Here the VISIBLE vertices refer to vertices that are within the robot’s <em>line of sight</em>, but visibility does not imply that there’s a clear direct path. For instance, a vertex could be visible through a narrow opening or in a way that doesn’t guarantee a straight-line route to it without obstruction. So the robot might see the vertex, but obstacles between the robot and the vertex could prevent a direct uninterrupted path.</p>
  <p>The intent behind this exercise is to simulate a realistic scenario where visibility does not guarantee accessibility which challenges the reader to handle cases where the robot must detect and stop for obstacles along its planned straight path, even if it initially sees the destination vertex.</p>
  
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Answers.Text: The only way this makes sense to me is if we assume the robot has some size. So if it can see a vertex through a gap that is too small for it to fit then it just collides with the objects. If we assume the robot is just a point then none of this makes sense to me. Is that what you are getting at? That is, the robot has some non-negligible size?
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Answers.Text: @HMPtwo You've identified a key point. This interpretation indeed makes the most sense if we assume the robot has a non-negligible physical size. Only if the robot has a size, there could be narrow gaps or obstacles along the path that would stop it, even if it could see its target vertex. This assumption means that the robot’s collision detection goes beyond a simple “line-of-sight” assessment, it also checks if the path itself can accommodate its body. Hope this clarifies my answer.
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Answers.Text: Brilliant answer and thanks for clarifying. :) Time to plan it and code it up.
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Body: <p>The exercise asks the reader to create an agent that receives percepts in the form of VISIBLE vertices. Then goes on to describe an action in response to a particular percept as  a &quot;vector describing a straight-line path to follow&quot;.</p>
  <p>All good so far. But then &quot;If the path is unobstructed, the action succeeds; otherwise, the robot stops at the point where its path first intersects an obstacle&quot;. Here is a screenshot:</p>
  <p><a href="https://i.sstatic.net/AJhn3zP8.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/AJhn3zP8.png" alt="Screenshot" /></a></p>
  <p>Surely the vertex would not be visible in the first place for an intersection to occur? Could someone help me understand what is actually being asked?</p>
  
Tags: <environment>
Title: Creating an agent as per exercise 4.11 of Artificial Intelligence: A Modern Approach
UserDisplayName: HMPtwo
ThreadText: # Creating an agent as per exercise 4.11 of Artificial Intelligence: A Modern Approach
  
  (Asked by: username_0 on 2024-10-30)
  
  The exercise asks the reader to create an agent that receives percepts in the form of VISIBLE vertices. Then goes on to describe an action in response to a particular percept as a "vector describing a straight-line path to follow".
  
  All good so far. But then "If the path is unobstructed, the action succeeds; otherwise, the robot stops at the point where its path first intersects an obstacle". Here is a screenshot:
  
  [![Screenshot](https://i.sstatic.net/AJhn3zP8.png)](https://i.sstatic.net/AJhn3zP8.png)
  
  Surely the vertex would not be visible in the first place for an intersection to occur? Could someone help me understand what is actually being asked?
  
  **Tags:** environment
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2024-10-31. Score: 1 | Accepted answer
  
  Here the VISIBLE vertices refer to vertices that are within the robot’s *line of sight*, but visibility does not imply that there’s a clear direct path. For instance, a vertex could be visible through a narrow opening or in a way that doesn’t guarantee a straight-line route to it without obstruction. So the robot might see the vertex, but obstacles between the robot and the vertex could prevent a direct uninterrupted path.
  
  The intent behind this exercise is to simulate a realistic scenario where visibility does not guarantee accessibility which challenges the reader to handle cases where the robot must detect and stop for obstacles along its planned straight path, even if it initially sees the destination vertex.
  
  > **Comments:**
  > **username_0**: The only way this makes sense to me is if we assume the robot has some size. So if it can see a vertex through a gap that is too small for it to fit then it just collides with the objects. If we assume the robot is just a point then none of this makes sense to me. Is that what you are getting at? That is, the robot has some non-negligible size?  
  > **username_1**: @HMPtwo You've identified a key point. This interpretation indeed makes the most sense if we assume the robot has a non-negligible physical size. Only if the robot has a size, there could be narrow gaps or obstacles along the path that would stop it, even if it could see its target vertex. This assumption means that the robot’s collision detection goes beyond a simple “line-of-sight” assessment, it also checks if the path itself can accommodate its body. Hope this clarifies my answer.  
  > **username_0**: Brilliant answer and thanks for clarifying. :) Time to plan it and code it up.  
  
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