Enhanced Realizability Interpretation for Program Extraction

This thesis presents Intuitionistic Fixed Point Logic (IFP), a schema for formal systems aimed to work with program extraction from proofs. IFP in its basic form allows proof construction based on natural deduction inference rules, extended by induction and coinduction. The corresponding system RIFP (IFP with realiz-ers) enables transforming logical proofs into programs utilizing the enhanced re-alizability interpretation. The theoretical research is put into practice in PRAWF1, a Haskell-based proof assistant for program extraction

Formally Verified Space-Safety for Program Transformations

Existing work on compilers has often primarily concerned itself with preserving behavior, but programs have other facets besides their observable behavior. We expect that the performance of our code is preserved and bettered by the compiler, not made worse. Unfortunately, that\u27s exactly what sometimes occurs in modern optimizing compilers. Poor representations or incorrect optimizations may preserve the correct behavior, but push that program into a different complexity class entirely. We\u27ve seen such blowups like this occurring in practice, and many transformations have pitfalls which can cause issues. Even when a program is not dramatically worsened, it can cause the program to use more resources than expected, causing issues in resource-constrained environments, and increasing garbage-collection pauses. While several researchers have noticed potential issues, there have been a relative dearth of proofs for space-safety, and none at all concerning non-local optimizations. This work expands upon existing notions of space-safety, allowing them to be used to reason about long-running programs with both input and output, while ensuring that the program maintains some temporal locality of space costs. In addition, this work includes new proof techniques which can handle more dramatic shifts in the program and heap structure than existing methods, as well as more frequent garbage collection. The results are formalized in Coq, including a proof of space-safety for lifting data up in scope, which increases sharing and saves duplicate work, but may also catastrophically increase space usage, if done incorrectly

Intuitionistic fixed point logic

The logical system IFP introduced in this paper supports program extraction from proofs, unifying theoretical and practical advantages: Based on first-order logic and powerful strictly positive inductive and coinductive definitions, IFP support abstract axiomatic mathematics with a large amount of classical logic. The Haskell-like target programming language has a denotational and an operational semantics which are linked through a computational adequacy theorem that extends to infinite data. Program extraction is fully verified and highly optimised, thus extracted programs are guaranteed to be correct and free of junk. A case study in exact real number computation underpins IFP's effectiveness

Optimality in Goal-Dependent Analysis of Sharing

We face the problems of correctness, optimality and precision for the static analysis of logic programs, using the theory of abstract interpretation. We propose a framework with a denotational, goal-dependent semantics equipped with two unification operators for forward unification (calling a procedure) and backward unification (returning from a procedure). The latter is implemented through a matching operation. Our proposal clarifies and unifies many different frameworks and ideas on static analysis of logic programming in a single, formal setting. On the abstract side, we focus on the domain Sharing by Jacobs and Langen and provide the best correct approximation of all the primitive semantic operators, namely, projection, renaming, forward and backward unification. We show that the abstract unification operators are strictly more precise than those in the literature defined over the same abstract domain. In some cases, our operators are more precise than those developed for more complex domains involving linearity and freeness. To appear in Theory and Practice of Logic Programming (TPLP

Modelling and control for the oscillating water column

xxii, 219 p.Renewable energies are definitely part of the equation to limit our dependence to fossil fuels. Within this sector, ocean energies, and especially wave energy, represent a huge potential but is still a growing area. And like any new field, it is synonym to a high cost of energy production. Increasing the energy production, while keeping the costs controlled, has the leverage to drop down the cost of energy produced by wave energy converters (WECs). The main objective of this thesis is to make progress on the understanding of the effect of advanced control algorithms in the improvement of the power produced by wave energy devices. For that purpose, several control strategies are designed, compared, and assessed. To support this analysis, numerical models representing the overall energy conversion chain of WECs are developed. The Basque Country in Spain is fortunate enough to host the development and operation of two devices based on the Oscillating Water Column (OWC) principle. One is the Mutriku OWC plant, and the second is the floating buoy Marmok-A from Oceantec/IDOM, both devices were made available for sea trials. Several control algorithms were then implemented to be tested in real environments. Among them was a non-linear predictive control algorithm. Its test in real conditions represent a world first in the area of control for OWC systems, and maybe for the whole WEC sector if comparing with publicly available information. An outstanding results of the thesis is undoubtedly to move forward the predictive control algorithm from TRL3 to TRL6 after successful implementation and operation in both devices under real environmental conditions

Modelling and control for the oscillating water column

xxii, 219 p.Renewable energies are definitely part of the equation to limit our dependence to fossil fuels. Within this sector, ocean energies, and especially wave energy, represent a huge potential but is still a growing area. And like any new field, it is synonym to a high cost of energy production. Increasing the energy production, while keeping the costs controlled, has the leverage to drop down the cost of energy produced by wave energy converters (WECs). The main objective of this thesis is to make progress on the understanding of the effect of advanced control algorithms in the improvement of the power produced by wave energy devices. For that purpose, several control strategies are designed, compared, and assessed. To support this analysis, numerical models representing the overall energy conversion chain of WECs are developed. The Basque Country in Spain is fortunate enough to host the development and operation of two devices based on the Oscillating Water Column (OWC) principle. One is the Mutriku OWC plant, and the second is the floating buoy Marmok-A from Oceantec/IDOM, both devices were made available for sea trials. Several control algorithms were then implemented to be tested in real environments. Among them was a non-linear predictive control algorithm. Its test in real conditions represent a world first in the area of control for OWC systems, and maybe for the whole WEC sector if comparing with publicly available information. An outstanding results of the thesis is undoubtedly to move forward the predictive control algorithm from TRL3 to TRL6 after successful implementation and operation in both devices under real environmental conditions

Intuitionistic Fixed Point Logic

We study the system IFP of intuitionistic fixed point logic, an extension of intuitionistic first-order logic by strictly positive inductive and coinductive definitions. We define a realizability interpretation of IFP and use it to extract computational content from proofs about abstract structures specified by arbitrary classically true disjunction free formulas. The interpretation is shown to be sound with respect to a domain-theoretic denotational semantics and a corresponding lazy operational semantics of a functional language for extracted programs. We also show how extracted programs can be translated into Haskell. As an application we extract a program converting the signed digit representation of real numbers to infinite Gray-code from a proof of inclusion of the corresponding coinductive predicates.Comment: 65 page

MILCS: A mutual information learning classifier system

This paper introduces a new variety of learning classifier system (LCS), called MILCS, which utilizes mutual information as fitness feedback. Unlike most LCSs, MILCS is specifically designed for supervised learning. MILCS's design draws on an analogy to the structural learning approach of cascade correlation networks. We present preliminary results, and contrast them to results from XCS. We discuss the explanatory power of the resulting rule sets, and introduce a new technique for visualizing explanatory power. Final comments include future directions for this research, including investigations in neural networks and other systems. Copyright 2007 ACM