Generalization Strategies for the Verification of Infinite State Systems

We present a method for the automated verification of temporal properties of infinite state systems. Our verification method is based on the specialization of constraint logic programs (CLP) and works in two phases: (1) in the first phase, a CLP specification of an infinite state system is specialized with respect to the initial state of the system and the temporal property to be verified, and (2) in the second phase, the specialized program is evaluated by using a bottom-up strategy. The effectiveness of the method strongly depends on the generalization strategy which is applied during the program specialization phase. We consider several generalization strategies obtained by combining techniques already known in the field of program analysis and program transformation, and we also introduce some new strategies. Then, through many verification experiments, we evaluate the effectiveness of the generalization strategies we have considered. Finally, we compare the implementation of our specialization-based verification method to other constraint-based model checking tools. The experimental results show that our method is competitive with the methods used by those other tools. To appear in Theory and Practice of Logic Programming (TPLP).Comment: 24 pages, 2 figures, 5 table

Fuzz on the Beach: Fuzzing Solana Smart Contracts

Solana has quickly emerged as a popular platform for building decentralized applications (DApps), such as marketplaces for non-fungible tokens (NFTs). A key reason for its success are Solana's low transaction fees and high performance, which is achieved in part due to its stateless programming model. Although the literature features extensive tooling support for smart contract security, current solutions are largely tailored for the Ethereum Virtual Machine. Unfortunately, the very stateless nature of Solana's execution environment introduces novel attack patterns specific to Solana requiring a rethinking for building vulnerability analysis methods. In this paper, we address this gap and propose FuzzDelSol, the first binary-only coverage-guided fuzzing architecture for Solana smart contracts. FuzzDelSol faithfully models runtime specifics such as smart contract interactions. Moreover, since source code is not available for the large majority of Solana contracts, FuzzDelSol operates on the contract's binary code. Hence, due to the lack of semantic information, we carefully extracted low-level program and state information to develop a diverse set of bug oracles covering all major bug classes in Solana. Our extensive evaluation on 6049 smart contracts shows that FuzzDelSol's bug oracles find bugs with a high precision and recall. To the best of our knowledge, this is the largest evaluation of the security landscape on the Solana mainnet.Comment: This paper will appear on the ACM CCS 2023 in November 202

Pando: Personal Volunteer Computing in Browsers

The large penetration and continued growth in ownership of personal electronic devices represents a freely available and largely untapped source of computing power. To leverage those, we present Pando, a new volunteer computing tool based on a declarative concurrent programming model and implemented using JavaScript, WebRTC, and WebSockets. This tool enables a dynamically varying number of failure-prone personal devices contributed by volunteers to parallelize the application of a function on a stream of values, by using the devices' browsers. We show that Pando can provide throughput improvements compared to a single personal device, on a variety of compute-bound applications including animation rendering and image processing. We also show the flexibility of our approach by deploying Pando on personal devices connected over a local network, on Grid5000, a French-wide computing grid in a virtual private network, and seven PlanetLab nodes distributed in a wide area network over Europe.Comment: 14 pages, 12 figures, 2 table

Communication patterns abstractions for programming SDN to optimize high-performance computing applications

Orientador : Luis Carlos Erpen de BonaCoorientadores : Magnos Martinello; Marcos Didonet Del FabroTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Informática. Defesa: Curitiba, 04/09/2017Inclui referências : f. 95-113Resumo: A evolução da computação e das redes permitiu que múltiplos computadores fossem interconectados, agregando seus poderes de processamento para formar uma computação de alto desempenho (HPC). As aplicações que são executadas nesses ambientes processam enormes quantidades de informação, podendo levar várias horas ou até dias para completar suas execuções, motivando pesquisadores de varias áreas computacionais a estudar diferentes maneiras para acelerá-las. Durante o processamento, essas aplicações trocam grandes quantidades de dados entre os computadores, fazendo que a rede se torne um gargalo. A rede era considerada um recurso estático, não permitindo modificações dinâmicas para otimizar seus links ou dispositivos. Porém, as redes definidas por software (SDN) emergiram como um novo paradigma, permitindoa ser reprogramada de acordo com os requisitos dos usuários. SDN já foi usado para otimizar a rede para aplicações HPC específicas mas nenhum trabalho tira proveito dos padrões de comunicação expressos por elas. Então, o principal objetivo desta tese é pesquisar como esses padrões podem ser usados para ajustar a rede, criando novas abstrações para programá-la, visando acelerar as aplicações HPC. Para atingir esse objetivo, nós primeiramente pesquisamos todos os níveis de programabilidade do SDN. Este estudo resultou na nossa primeira contribuição, a criação de uma taxonomia para agrupar as abstrações de alto nível oferecidas pelas linguagens de programação SDN. Em seguida, nós investigamos os padrões de comunicação das aplicações HPC, observando seus comportamentos espaciais e temporais através da análise de suas matrizes de tráfego (TMs). Concluímos que as TMs podem representar as comunicações, além disso, percebemos que as aplicações tendem a transmitir as mesmas quantidades de dados entre os mesmos nós computacionais. A segunda contribuição desta tese é o desenvolvimento de um framework que permite evitar os fatores da rede que podem degradar o desempenho das aplicações, tais como, sobrecarga imposta pela topologia, o desbalanceamento na utilização dos links e problemas introduzidos pela programabilidade do SDN. O framework disponibiliza uma API e mantém uma base de dados de TMs, uma para cada padrão de comunicação, anotadas com restrições de largura de banda e latência. Essas informações são usadas para reprogramar os dispositivos da rede, alocando uniformemente as comunicações nos caminhos da rede. Essa abordagem reduziu o tempo de execução de benchmarks e aplicações reais em até 26.5%. Para evitar que o código da aplicação fosse modificado, como terceira contribuição, desenvolvemos um método para identificar automaticamente os padrões de comunicação. Esse método gera texturas visuais di_erentes para cada TM e, através de técnicas de aprendizagem de máquina (ML), identifica as aplicações que estão usando a rede. Em nossos experimentos, o método conseguiu uma taxa de acerto superior a 98%. Finalmente, nós incorporamos esse método ao framework, criando uma abstração que permite programar a rede sem a necessidade de alterar as aplicações HPC, diminuindo em média 15.8% seus tempos de execução. Palavras-chave: Redes Definidas por Software, Padrões de Comunicação, Aplicações HPC.Abstract: The evolution of computing and networking allowed multiple computers to be interconnected, aggregating their processing powers to form a high-performance computing (HPC). Applications that run in these computational environments process huge amounts of information, taking several hours or even days to complete their executions, motivating researchers from various computational fields to study different ways for accelerating them. During the processing, these applications exchange large amounts of data among the computers, causing the network to become a bottleneck. The network was considered a static resource, not allowing dynamic adjustments for optimizing its links or devices. However, Software-Defined Networking (SDN) emerged as a new paradigm, allowing the network to be reprogrammed according to users' requirements. SDN has already been used to optimize the network for specific HPC applications, but no existing work takes advantage of the communication patterns expressed by those applications. So, the main objective of this thesis is to research how these patterns can be used for tuning the network, creating new abstractions for programming it, aiming to speed up HPC applications. To achieve this goal, we first surveyed all SDN programmability levels. This study resulted in our first contribution, the creation of a taxonomy for grouping the high-level abstractions offered by SDN programming languages. Next, we investigated the communication patterns of HPC applications, observing their spatial and temporal behaviors by analyzing their traffic matrices (TMs). We conclude that TMs can represent the communications, furthermore, we realize that the applications tend to transmit the same amount of data among the same computational nodes. The second contribution of this thesis is the development of a framework for avoiding the network factors that can degrade the performance of applications, such as topology overhead, unbalanced links, and issues introduced by the SDN programmability. The framework provides an API and maintains a database of TMs, one for each communication pattern, annotated with bandwidth and latency constraints. This information is used to reprogram network devices, evenly placing the communications on the network paths. This approach reduced the execution time of benchmarks and real applications up to 26.5%. To prevent the application's source code to be modified, as a third contribution of our work, we developed a method to automatically identify the communication patterns. This method generates different visual textures for each TM and, through machine learning (ML) techniques, identifies the applications using the network. In our experiments the method succeeded with an accuracy rate over 98%. Finally, we incorporate this method into the framework, creating an abstraction that allows programming the network without changing the HPC applications, reducing on average 15.8% their execution times. Keywords: Software-Defined Networking, Communication Patterns, HPC Applications

RELFUN guide : programming with relations and functions made easy

A practical description of relational/functional programming in RELFUN is given. The language constructs are introduced by a tutorial dialog. Builtins, primitives, and commands are explained. Examples are given on all aspects relevant to using the language

Strategies to induce an inflammatory response: a focus on alternatives for people restricted to engage in lower-body exercise

INTRODUCTION. Chronic low-grade inflammation is increasingly recognised as a risk factor for non-communicable diseases such as type 2 diabetes mellitus and cardiovascular disease. Regular exercise has a protective effect against these type of diseases, possibly partially resulting from the acute inflammatory response and the subsequent anti-inflammatory milieu created following each bout of exercise. This acute response is characterised by an increased production of interleukin (IL)-6, heat shock protein 72 (Hsp72), and anti-inflammatory cytokines such as IL-1ra and IL-10. However, engaging in exercise of sufficient volume to induce an acute inflammatory response may not be feasible for those who are restricted to be physically active. In this thesis, factors that may influence the acute inflammatory response to exercise are investigated to inform strategies to reduce chronic low-grade inflammation in people with a low physical capacity. Furthermore, the efficacy of 2 such strategies, namely upper-body high-intensity interval training (HIIT) and hot water immersion (HWI), to induce an acute inflammatory response is investigated. Moreover, the effect of a chronic HWI intervention on the inflammatory profile and metabolic markers at rest is assessed. METHODS. In Chapters 2 and 3, factors that may influence the acute inflammatory response to exercise are investigated. The impact of chronic, modality-specific training adaptations and active muscle mass is investigated in individuals chronically trained in either upper- or lower-body exercise, while the role of autonomic function is studied in wheelchair athletes taking part in a wheelchair half-marathon. Thereafter, studies exploring the efficacy of relatively novel health promoting strategies to improve the inflammatory profile are presented. The acute increase in IL-6 and IL-1ra concentrations following upper-body HIIT is compared with moderate-intensity upper-body exercise in Chapter 4. In Chapters 5 and 6, the acute and chronic effects of HWI on inflammatory and metabolic markers in sedentary overweight males are studied. Finally, an in-vitro model is used to gain more insight in the potential of temperature elevations to induce an acute inflammatory response in monocytes (Chapter 7). The main inflammatory markers investigated in the present thesis are IL-6, intracellular Hsp72 in monocytes, extracellular Hsp72 and the distribution of monocyte subsets. Alongside the inflammatory markers, perceptual responses are collected to help inform the implementation of the studied interventions. RESULTS. Chronic modality-specific training adaptations, the reduced active muscle mass and autonomic dysfunction have all shown to attenuate the acute inflammatory response following upper-body exercise. Although HIIT did not result in a larger acute increase in plasma IL-6 and IL-1ra concentrations, it was more time efficient and perceived as more enjoyable than moderate-intensity continuous exercise. A single HWI session induced an acute elevation in plasma IL-6 concentration, as well as a shift in the monocyte subset distribution. However, this was not accompanied by an increase in iHsp72 expression. A higher core temperature than observed in Chapter 5 (38.7±0.4℃) may be needed to increase iHsp72 expression; which was supported by the results of Chapter 7, where incubation of whole blood at 40℃ but not 38.5℃ increased iHsp72 expression in monocytes. A chronic 2-week HWI intervention reduced fasting glucose and insulin as well as eHsp72 concentrations at rest. No change in resting IL-6 or iHsp72 was observed following the intervention. CONCLUSION. The observation that a range of factors can reduce the potential of exercise to induce an acute inflammatory response in people restricted to engage in (lower-body) exercise may warrant additional health promoting strategies to reduce chronic low-grade inflammation in these individuals. The results of the present thesis support the potential of body temperature manipulations to be such a strategy. The lowering of fasting glucose and insulin, as well as eHsp72 following a relatively short-term chronic HWI intervention suggest that passively increasing body temperature may be a viable tool to improve the inflammatory profile and metabolic health in people restricted to be physically active

Restrição proteica e estresse oxidativo em ratos submetidos ou não ao exercicio fisico

Orientador: Maria Alice Rostom de MelloTese (doutorado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: Seres humanos e animais desnutridos apresentam comprometimento funcional em diversos órgãos, o que não é revertido totalmente pela realimentação. O exercício físico, por sua vez. parece acelerar alguns aspectos da recuperação nutricionaL São escassos os dados quanto ao envolvimento do estresse oxidativo no comprometimento funcional causado pela desnutrição. Mais raras ainda são as informações quanto aos efeitos do exercício durante a recuperação nutricional sobre o estresse oxidativo imposto ao organismo. O presente estudo visou avaliar o balanço entre ataque oxidativo e mecanismos antioxidantes em ratos jovens submetidos à restrição protéica alimentar e recuperados com dieta balanceada, associada ou não ao exercício aeróbio de corrida e natação. Os principais indicadores do ataque oxidativo foram os produtos que reagem ao ácido tiobarbitúrico (TBARs) e as proteínas carboniladas (PC) enquanto que os indicadores do sistema de defesa antioxidante foram as atividades das enzimas catalase (CAT) e glutationa redutase (GR) no sangue. Os animais deficientes em proteína apresentaram aumento dos danos oxidativos (TBARs) em relação aos controles, o que induziu aumento na atividade das enzimas antioxidantes. O treinamento físico aumentou os danos oxidativos (TBARs) e reduziu as enzimas antioxidantes (CAT e GR) nos animais controles. O treinamento físico durante a recuperação nutricional, independente do tipo de exercício, acelerou o crescimento corporal (ganho de peso) dos ratos deficientes em proteína sem aumentar os danos oxidativos (TBARs). Ambos os tipos de treinamento reduziram a atividade da CA T durante a realimentação. O treinamento por natação reduziu também a atividade GR. Em resumo, o conjunto de resultados sugere que a melhora do cresdmento corporal durante a recuperação nutricional associada ao treinamento físico, pode estar relacionada, ao menos em parte, ao decréscimo do nível de estresse oxidativoAbstract: Malnourished human beings and animais show impaired function in several organs, which is not a fully reversed by nutritional recovery. Physical training, in turn, accelerates some aspects of nutritional recovery. There are few data on the participation of oxidative stress in the functional impairment imposed by malnutrition. The literatura locks information on the effects of physical training associated to nutritional recovery on oxidative stress. The present study was designed to evaluate the balance between oxidative attack and antioxidant mechanisms in young rats submitted to alimentary pratein restriction and recovered with balanced diet associated or not to aerobic physical training (swimming and running). The main oxidative damage biomarkers was the blood thiobarbituric acid reactive substances amount (TBARs) and reactive carbonyl derivatives (RCD) amounts while the antioxidant system biomarkers were the blood catalase (CAT) and glutathione reductase (GR) activities. Pratein deficient animais showed increase the in oxidative damage (TBARs) in relation to controls that induced an increase in antioxidant enzymes activity (CAT and GR). Physical training increased oxidative damage (TBARs) and reduced antioxidant defense (CAT and GR) in control animais. Physical training during nutritional recovery accelerated body growth (weight gain) of pratein restricted rats without increasing oxidative damage (TBARs). Both swim and run training reduced CA T activity during nutritional recovery. Swim training reduced also GR activity. In summary, taken together these results suggest that the improvement in body growth during nutritional recovery associated to physical training may be related, at least in part to a decrease in the oxidative stress levelsDoutoradoBioquimicaDoutor em Biologia Funcional e Molecula