-the-shelf legacy C programs. The method takes as input the buggy C source code, a failed test case that demonstrates the bug, and a small number of other test cases that encode the required functionality of the program. The repair procedure does not rely on formal specifications, making it applicable to a wide

valid in general. • Declarative style. Reactive behavior is defined in a direct, convenient, declarative style instead of encoding it in design patterns or through imperative updates of program state. Reactions are directly expressed and do not need to be encoded into the control flow of the program

Commutative, idempotent groupoids and the

We study highly expressive query languages for unordered data trees, using as formal vehicles Active XML and extensions of languages in the while family. All languages may be seen as adding some form of control on top of a set of basic pattern queries. The results highlight the impact and interplay

and backchase

officialssudden, pervasive infection in all age groups on a global scale, due in part to their unusual genomic properties. Rapid rates of from around the world have begun to devise strategies by which influenza-related morbidity, mortality, and social disruptionevolution in the genes that encode the major

problem. State identification techniques use history information to uncover hidden state. Previous approaches to encoding history include: finite state machines [ Chrisman, 1992; McCallum, 1992a ] , recurrent neural networks [ Lin and Mitchell, 1992 ] and genetic programming with indexed memory [ Teller

on advanced type-theoretic machinery that is not easily integrated into established theorem provers. We present Mtac, a lightweight but powerful extension to Coq that supports dependently typed tactic programming. Mtac tactics have access to all the features of ordinary Coq programming, as well as a new set

ii iv vTo my parents vi vii Acknowledgements I would first and foremost extend my whole-hearted gratitude to my advisors, An-drea Arpaci-Dusseau and Remzi Arpaci-Dusseau. Andrea and Remzi are the reason that I had the opportunity for this exceptional Ph.D. journey. To this day, I still re-member the moment when they took me as their student and the joy and hope in my heart. Andrea and Remzi have showed me what systems research is like and how much fun and challenging it can be. Before this journey with them, I had always liked and believed in the beauty of mathematics and theory. My initial interest in systems research happened when I took Remzi’s Advanced Operating Systems

structures, and show how this duality enables us to convert between imperative and declarative views of programs, by treating states and events on the same footing. We provide pictorial representations of both these views, each encoding all the information to convert to the other. We define a process algebra