Extempore: The design, implementation and application of a cyber-physical programming language

There is a long history of experimental and exploratory programming supported by systems that expose interaction through a programming language interface. These live programming systems enable software developers to create, extend, and modify the behaviour of executing software by changing source code without perceptual breaks for recompilation. These live programming systems have taken many forms, but have generally been limited in their ability to express low-level programming concepts and the generation of efficient native machine code. These shortcomings have limited the effectiveness of live programming in domains that require highly efficient numerical processing and explicit memory management. The most general questions addressed by this thesis are what a systems language designed for live programming might look like and how such a language might influence the development of live programming in performance sensitive domains requiring real-time support, direct hardware control, or high performance computing. This thesis answers these questions by exploring the design, implementation and application of Extempore, a new systems programming language, designed specifically for live interactive programming

Basic concepts in quantum computation

Section headings: 1 Qubits, gates and networks 2 Quantum arithmetic and function evaluations 3 Algorithms and their complexity 4 From interferometers to computers 5 The first quantum algorithms 6 Quantum search 7 Optimal phase estimation 8 Periodicity and quantum factoring 9 Cryptography 10 Conditional quantum dynamics 11 Decoherence and recoherence 12 Concluding remarksComment: 37 pages, lectures given at les Houches Summer School on "Coherent Matter Waves", July-August 199

Passively Mobile Communicating Logarithmic Space Machines

We propose a new theoretical model for passively mobile Wireless Sensor Networks. We call it the PALOMA model, standing for PAssively mobile LOgarithmic space MAchines. The main modification w.r.t. the Population Protocol model is that agents now, instead of being automata, are Turing Machines whose memory is logarithmic in the population size n. Note that the new model is still easily implementable with current technology. We focus on complete communication graphs. We define the complexity class PLM, consisting of all symmetric predicates on input assignments that are stably computable by the PALOMA model. We assume that the agents are initially identical. Surprisingly, it turns out that the PALOMA model can assign unique consecutive ids to the agents and inform them of the population size! This allows us to give a direct simulation of a Deterministic Turing Machine of O(nlogn) space, thus, establishing that any symmetric predicate in SPACE(nlogn) also belongs to PLM. We next prove that the PALOMA model can simulate the Community Protocol model, thus, improving the previous lower bound to all symmetric predicates in NSPACE(nlogn). Going one step further, we generalize the simulation of the deterministic TM to prove that the PALOMA model can simulate a Nondeterministic TM of O(nlogn) space. Although providing the same lower bound, the important remark here is that the bound is now obtained in a direct manner, in the sense that it does not depend on the simulation of a TM by a Pointer Machine. Finally, by showing that a Nondeterministic TM of O(nlogn) space decides any language stably computable by the PALOMA model, we end up with an exact characterization for PLM: it is precisely the class of all symmetric predicates in NSPACE(nlogn).Comment: 22 page