In this paper, we introduce the new technique of high-confidence software monitoring (HCSM), which allows one to perform software monitoring with bounded overhead and concomitantly achieve high confidence in the observed error rates. HCSM is formally grounded in the theory of supervisory control of finite-state automata: overhead is controlled, while maximizing confidence, by disabling interrupts generated by the events being monitored - and hence avoiding the overhead associated with processing these interrupts - for as short a time as possible under the constraint of a user-supplied target overhead Otarget. HCSM is a general technique for software monitoring in that HCSM-based instrumentation can be attached at any system interface or API. A generic controller implements the optimal control strategy described above. As a proof of concept, and as a practical framework for software monitoring, we have implemented HCSM-based monitoring for both bounds checking and memory leak detection. We have further conducted an extensive evaluation of HCSM's performance on several real-world applications, including the Lighttpd Web server, and a number of special-purpose micro-benchmarks. Our results demonstrate how confidence grows in a monotonically increasing fashion with the target overhead, and that tight confidence intervals can be obtained for each target-overhead level.

Solving the nuclear many-body problem engenders significant theoretical and computational challenges. I will briefly discuss the science that goes into and comes out of the nuclear problem, and then turn to the numerical implementations of coupled-cluster theory for the problem. Specific to the nuclear problem is the presence of real three-body forces which are computationally represented by six-dimensional tensors. Both memory and communications become issues as one begins to scale up the underlying coupled-cluster algorithms to thousands of processors. Another interesting feature of the nuclear problem is weak binding that occurs in very unstable nuclei. When the single-particle continuum is present, the nuclear Hamiltonian becomes complex. I also will describe our attempts to solve the complex coupled-cluster problem in the presence of complex interactions. Efficient parallelism requires spreading the interaction matrices globally and the coupled-cluster amplitudes in a more local fashion.