Probabilistic algorithms are all around us

“Probabilistic algorithms exist to solve problems that are either impossible or unrealistic (too expensive, too time-consuming, etc.) to solve precisely. In an ideal world, you would never actually need to use probabilistic algorithms. To programmers who are not familiar with them, the idea can be positively nerve-wracking: “How do I know that it will actually work? What if it’s inexplicably wrong? How can I debug it? Maybe we should just punt on this problem, or buy a whole lot more servers…”

However, to those who either deeply understand probability theory or at least have used and observed the behavior of probabilistic algorithms in large-scale production environments, these algorithms are not only acceptable, but it’s also worth seeking out opportunities to use them. This is because they can help solve problems and create systems that are less expensive, more predictable, and can do things that couldn’t be done otherwise.

The world is probabilistic—or at least it’s way too complex for us to model 100 percent accurately. Networks, and especially the Internet, are also probabilistic. Whether or not a particular packet will get where it needs to go is not something we can have complete knowledge of. Knowing which paths it will take through the many networks it will traverse in getting from one side of the world to the other is even less certain. Systems that run across asynchronous/ lossy networks are necessarily probabilistic. Like it or not, probability is all around us…”