Challenge 7

Quest for Communication

Challenge

The castle is protected with a code.  In order to gain access to the castle a turtle needs to know four code words.  A turtle can learn the words by running over one of the four colored patches that holds the secret words.  Watch the turtles learn the code words.  How long does it take them to get into the castle?  What happens if more patches hold the secret words?

The turtles need to figure out a faster way to get back into the castle.  Your challenge is to help them work together so that they can enter the castle more quickly.  By sharing the code words that they already know the turtles can help each other get into the castle.  The turtle-turtle communication algorithms used to model this information transfer are powerful components of any modeling environment.  Modeling interactions among creatures can enrich your existing models and broaden the scope of models you can create.

Add the following code fragment to the Turtle Procedures of (7)Castle Invasion to allow a pair of turtles to exchange information (in this example, the first code word), provided one of them already knows it [MSL Note# 16].

grab one-of-turtles-here 

  [if (code1 = none) and ((code1-of other) not= none)

        [setcode1 code1-of partner

         setnumber number + 1]   

   ]

Teach the turtles to exchange information about all of the four words instead of just one.  Then, try to determine if the enhanced information exchange affects how quickly the turtles can break into the castle.  What happens if you modify the way that they exchange information?  How does this change affect the time it takes them to gain access to the castle?

Possible Explorations

·        What would happen if you didn’t send turtles who knew all four words right into the castle?  What else might you do with these turtles?  How does this model compare to team projects in which no one person gets credit until the entire team has completed the challenge?

·        Try making a model where turtles exchange information based on a certain probability.

·        How do you think information exchange and eventual castle entry will be affected if the turtles occasionally forget words?  Can you implement that modification?

·        What if there was a cost (losing all of the known code words, dying, etc.) when a turtle tried to enter the castle without knowing all of the words?

·        What happens to the length of time to castle entry if you change the number of turtles?  What if you change the number of code words?

·        Apply this type of turtle-turtle communication to other projects that you have been working on.

For more information contact Vanessa Colella (vanessa@media.mit.edu) or Eric Klopfer (klopfer@mit.edu).