ELI5: Explain Like I'm 5

Differentially private analysis of graphs

Imagine you have a big picture with lots of little shapes on it. Some of the shapes are circles, some are squares, some are triangles, and so on. Each shape represents a person, and the picture shows how these people are connected to each other.

If we look at this picture, we might be able to learn some things about how these people are connected. For example, we might notice that some people are connected to lots of others, while others are only connected to a few. We might also notice that some groups of people are very tightly connected to each other, while others are more spread out.

But what if we want to learn these things without seeing the whole picture? This is where differential privacy comes in. This is a way of analyzing the picture in a way that protects the privacy of the people in it.

To do this, we first divide the picture into many small parts. Each part represents a small group of people. We then look at the shape of each part, to see whether it is mostly circles, squares, triangles, or something else. We can also look at how closely connected the people in each part are.

To protect the privacy of the people in the picture, we don't look at every part. Instead, we only look at a small random sample of them. This means that we might miss some important parts of the picture, but it also means that we don't get too much information about any one person or group.

Once we have looked at our sample of parts, we use some clever math to make sure that our conclusions are not too different from what we would have found if we had looked at the whole picture. This is called differential privacy, because we are trying to measure how much our conclusions have changed by looking at different parts of the picture.

By using differential privacy to analyze the picture, we can learn some things about how the people are connected without violating their privacy. It's like looking at a puzzle through a keyhole. We might not see the whole picture, but we can still get a sense of what it looks like.