2.6 Directed Acyclic Graphs (DAGs) & Scheduling

Scheduling Prerequisites


The prerequisites of some MIT subjects are given in the following table:

Direct Prerequisites Subject
18.01 6.042
18.01 18.02
18.01 18.03
8.01 8.02
8.01 6.01
6.042 6.046
18.02, 18.03, 8.02, 6.01 6.02
6.01,6.042 6.006
6.01 6.034
6.02 6.004

In the following sets of subjects, specify whether the set is a chain, anti-chain, or neither:
(Hint, draw a DAG for the subjects first!)

  1. 6.042, 6.046, 6.01

    Exercise 1

  2. 18.01, 6.02, 6.004

    Exercise 2
    A chain need not contain every possible element.

  3. 6.042, 6.02, 6.034

    Exercise 3

  4. What is the length of the longest anti-chain?

    Exercise 4

     


  5. How many terms do you need to graduate if you take classes following the schedule given by a topological sort of the DAG?

    Exercise 5

     

    Topological sorting provides a schedule for taking one class per term, so the number of terms is the number of classes.