The power of probabilistic thinking

Traditionally, software engineering has dealt in absolutes. For instance, we talk about a system being “correct” or “incorrect”, with the shades of grey in between occasionally acknowledged but rarely dealt with explicitly. And we typically employ logical, algebraic, relational and other representations and techniques that help us reason about software in such absolute terms. There of course have been notable exceptions to this, such as the use of statistical techniques in testing and debugging. But by and large, both researchers and practitioners have favored the relative comfort of an absolutist viewpoint in all aspects of development. In this talk, I will argue the benefits of taking a more thoroughly probabilistic approach in software engineering. Software engineering is rife with stochastic phenomena, and the vast majority of software systems operate in an environment of uncertain, random behavior, which suits an explicit probabilistic characterization. Furthermore, this uncertainty is becoming ever more pronounced in new software systems and platforms, such as the Internet of Things and autonomous vehicles, with their frequent imprecise outputs and heavy reliance on machine learning. To illustrate more deeply some of the considerations involved in taking a probabilistic approach, I will talk about some recent research I have been doing in probabilistic verification.