We will use sign language recognition as our first application of HMMs. For example, let’s consider the signs I and we and create HMMs for each of them. Here’s I. [BLANK_AUDIO] We is a little different. [BLANK_AUDIO] Let’s focus on the I gesture. We’ll use delta y as our first feature here. >> Wait a second. Why don’t we use delta x? It looks like it would be easier to differentiate the two words that way. While delta y is pretty similar for the both of them. >> That’s right. But I want to show exactly how powerful HMMs can be. So I have purposefully chosen a bad feature. We’ll actually still be able to tell the difference between the two words by the difference in timing. Let’s go through the process and see how that works. >> Okay, but sometimes it’s hard to visualize the derivative of a signal. Let’s have a quiz first to make sure we understand what you’re talking about.