As a programmer working for Logica UK in London in the mid-1980’s, I became a passionate advocate of formal methods. Extrapolating from small successes with VDM and JSP, I was sure that widespread use of formal methods would bring an end to the software crisis.

One approach especially intrigued me. John Guttag and Jim Horning had developed a language, called Larch, which was amenable to a mechanical analysis. In a paper they’d written a few years earlier [23], and which is still not as widely known as it deserves to be, they showed how questions about a design might be answered automatically. In other words, we would have real software “blueprints”—a way to analyze the essence of the design before committing to code. I went to pursue my PhD with John at MIT, and have been a researcher ever since.

In Software Abstractions Daniel Jackson introduces an approach to software design that draws on traditional formal methods but exploits automated tools to find flaws as early as possible. This approach--which Jackson calls "lightweight formal methods" or "agile modeling"--takes from formal specification the idea of a precise and expressive notation based on a tiny core of simple and robust concepts but replaces conventional analysis based on theorem proving with a fully automated analysis that gives designers immediate feedback. Jackson has developed Alloy, a language that captures the essence of software abstractions simply and succinctly, using a minimal toolkit of mathematical notions. This revised edition updates the text, examples, and appendixes to be fully compatible with the latest version of Alloy (Alloy 4).

The designer can use automated analysis not only to correct errors but also to make models that are more precise and elegant. This approach, Jackson says, can rescue designers from "the tarpit of implementation technologies" and return them to thinking deeply about underlying concepts. Software Abstractions introduces the key elements: a logic, which provides the building blocks of the language; a language, which adds a small amount of syntax to the logic for structuring descriptions; and an analysis, a form of constraint solving that offers both simulation (generating sample states and executions) and checking (finding counterexamples to claimed properties).