Hello everyone, and welcome to the class on probabilistic graphical models. My name is Daphne Koller and I’m a professor at Stanford University. We here at Stanford are really excited to be able to offer this graduate level Stanford class to anyone, anywhere around the world for free. So what are probabilistic graphical models? Well, it’s a bit complicated to explain and we’re going to talk about that in an upcoming video but also throughout the entire class. In this video, I’d like to tell you a little bit about the format of this class. The course is going to be offered over ten weeks worth of material plus a final examination at the end. The content is going to be conveyed via a set of videos, augmented with quizzes to reinforce understanding. In addition, there is going to be a weekly problem set where the problem sets altogether are going to be worth 25% of the score for a total of the nine problem sets for the nine weeks worth of content. The problem sets are designed to allow for multiple submissions, so that each version of the problem set is going to be a little bit different so that you can resubmit the same problem set [a] couple of times to make sure that you really mastered the material. In addition, there’s going to be a weekly programming assignment, and those programming assignments were selected to reinforce specific concepts that we’re studying in the course, but at the same time to reveal the range of applications to which the framework of probabilistic graphical models can be successfully applied. So we’re going to have, for example, a problem set on how you use probabilistic graphical models to understand the inheritance of genetically inherited diseases. We’re going to have one that shows how you can look at a set of handwritten characters and read what’s written there. And we’re going to have one that allows you to look at a stream of output from a Kinect sensor that gives you both video and range data and recognize human activities. These nine programming assignments are each going to be worth 7% of the score for a total of 63%, which gives us 12% left for the final exam. What background do you need for this class? Well, it’s going to be really hard to do this class, without some understanding of basic probability theory. This doesn’t have to be very advanced stuff. We’re talking about things like independence and Bayes' rule And just basics of discrete distributions. And we also have a few introductory modules to refresh your memory about these basic concepts. The programming assignments will require that you’ve had some experience programming before because this is not a programming class. We don’t teach you how to program. And because this class merges ideas from both probability theory and computer science, it’s really important you have some background in algorithms and data structures. Recommended, but not strictly necessary— and we certainly don’t require it, and we give you the background as we go— is a little bit of experience, perhaps, in machine learning, maybe some simple optimization like gradient descent, nothing very sophisticated. And it would be helpful to have some experience programming in Matlab or Octave, although, here also, we have some introductory modules that help you learn this programming language if you haven’t played around with it before. A few other issues that are worth noting: This class has an honor code. This is the norm also for our local Stanford students when they’re taking a Stanford class. The honor code here says that you’re allowed to discuss the material, in fact even encouraged to discuss the material with your fellow classmates. You can even ask clarifying questions about the problems sets and the programming assignments. But what you turn in has to be your own work. Furthermore, we request that you do not post either the programming assignments or their solutions anywhere on the web, so that future generations of students can do the problems sets and the programming assignments independently as well. A second issue to keep in mind is that of time management. This is a graduate-level Stanford class and it’s considered a difficult one even at Stanford. A typical Stanford student can easily spend ten to fifteen hours a week on this class, and so we would suggest that you budget at least that amount of time for your own efforts on this class if you don’t want to find yourself running out of time when a submission deadline comes around. We’ve built in a little slack into the submission deadline, so if you don’t manage to submit by the original deadline, you have a week’s worth of grace period. But then that obviously starts to impinge on the next week’s problem set. So we advise that you don’t just keep a backlog of assignments throughout the course, because it will all end up coming back to bite you in the end. Finally, part of the experience of this class is interacting with your fellow students, so for that purpose we have the discussion forum which has proven in other classes to be an invaluable resource for interacting with other students, asking questions and obtaining a deeper understanding of the material. We’re also encouraging you to form study groups— these can be physical study groups with people in the same geographical region, or online study groups where you can just discuss the material with each other. We believe that doing this will give you a much better understanding of the material and will make the course considerably more fun as well. So, to summarize, through all these different pieces of the content and the exercises, we think that you’ll learn fundamental methods in this area of probabilistic graphical models. You’ll also get to see and play around with a range of real-world applications for which these methods have been applied and hopefully you will leave this class with an understanding of how to take these ideas and use them in your own work in problems that you care about. We look forward to seeing you in this class.