Carnegie Mellon University

Christian Kästner

Dr. Christian Kästner

Associate Professor; Director, Software Engineering Ph.D. program

5000 Forbes Avenue
Pittsburgh, PA 15213


I am an associate professor in the School of Computer Science at Carnegie Mellon University, interested in limits of modularity and complexity caused by variability in software systems. I develop mechanisms, languages, and tools to implement variability in a disciplined way despite imperfect modularity, to understand feature interactions and interoperability issues, to detect errors, to help with nonmodular changes, and to improve program comprehension in software systems, typically systems with a high amount of variability. Among others, I have developed approaches to parse and type check all compile-time configurations of the Linux kernel in the TypeChef project.


Quality Assurance for Highly-Configurable Software Systems

We explore approaches to scale quality assurance strategies, including parsing, type checking, data-flow analysis, and testing, to huge configuration spaces in order to find variability bugs and detect feature interactions: Variational Analysis · Analysis of Unpreprocessed C Code · Variational Type Checking and Data-Flow Analysis · Variational Execution (Testing) · Sampling · Feature Interactions · Variational Specifications · Assuring and Understanding Quality Attributes as Performance and Energy · Security


Working with Imperfect Modularity

We explore mechanisms to support developers in scenarios in which traditional modularity mechanisms face challenges; among others, we explore strategies to complement modularity mechanisms with tooling: Virtual Separation of Concerns · Awareness for Evolution in Software Ecosystems · Conceptual Discussions


Maintenance and Implementation of Highly-Configurable Systems

We explore a wide range of different variability implementation mechanisms and their tradeoffs; in addition, we explore reverse engineering and refactoring mechanisms for variability and support developers with variability-related maintenance: Reverse Engineering Variability Implementations · Feature-Oriented Programming · Assessing and Understanding Configuration-Related Complexity · Understanding Preprocessor Use · Tracking Load-Time Configuration Options · Build Systems · Modularity and Feature Interactions


Variability Mechanisms Beyond Configurable Software Systems

We explore how analyses developed for variability can solve problems in contexts beyond software product lines, such as design space exploration, that share facets of the problem such as large finite search spaces with similarities among candidates: Developer Support and Quality Assurance for PHP · Sensitivity Analysis · Tests and Patches


Other Topics

We have collaborated on a number of other software engineering and programming languages topics, including dynamic software updates, extensible domain-specific languages, software merging, and various empirical methods topics: Understanding Program Comprehension with fMRI