Local Search For SMT On Linear and Multilinear Real Arithmetic

Satisfiability Modulo Theories (SMT) has significant application in various domains. In this paper, we focus on quantifier-free Satisfiablity Modulo Real Arithmetic, referred to as SMT(RA), including both linear and non-linear real arithmetic theories. As for non-linear real arithmetic theory, we focus on one of its important fragments where the atomic constraints are multi-linear. We propose the first local search algorithm for SMT(RA), called LocalSMT(RA), based on two novel ideas. First, an interval-based operator is proposed to cooperate with the traditional local search operator by considering the interval information. Moreover, we propose a tie-breaking mechanism to further evaluate the operations when the operations are indistinguishable according to the score function. Experiments are conducted to evaluate LocalSMT(RA) on benchmarks from SMT-LIB. The results show that LocalSMT(RA) is competitive with the state-of-the-art SMT solvers, and performs particularly well on multi-linear instances

Trabalhadores chineses em Portugal: desafios e sugestões, tendo como base uma experiência de estágio

Relatório de estágio de mestrado em Estudos Interculturais Português/Chinês: Tradução, Formação e Comunicação EmpresarialAtualmente, a China e a globalização são tópicos mais frequentes da nossa vida do dia-a-dia. O impacto da economia chinesa está a ser fortemente sentido, por tudo o mundo, e os seus negócios estão a expandir e crescer pelos quatro cantos do planeta, incluindo Portugal. Com o lançamento do “Programa dos Vistos Gold”, com as mais próximas relações diplomáticas entre a China e Portugal, cada vez mais chineses fazem negócios e investimentos em Portugal e, ao mesmo tempo, cada vez mais empresas portuguesas têm mais oportunidades de cooperar com empresas chinesas. No entanto, no processo de fazer negócios transnacionais, ambos os lados enfrentam uma enorme diversidade em termos de comunicação empresarial, o que de alguma forma criará mal-entendidos e trará complicações, assim como interferirá na produtividade do trabalho. Portanto, a primeira parte deste relatório centra-se na explicação das origens e das razões para a emigração de cidadãos chineses para Portugal, na identificação de diferenças entre portugueses e chineses em contexto de trabalho e na apresentação de alguns casos relacionados com problemas e desafios na comunicação empresarial. A segunda parte deste relatório apresentará brevemente a Câmara de Comércio e Indústria Luso-Chinesa, a sua missão, os seus órgãos sociais, os seus serviços, a sua história e os seus eventos representativos. A última parte deste relatório descreverá mais especificamente sobre os meus objetos, as minhas tarefas e o meu trabalho durante os meus quatro meses de estágio, além de mencionar alguns dos eventos importantes que eu participei.Nowadays, China and globalization are more and more common topics of our daily life. The impact of China’s economy is being strongly felt by the world, and its businesses are going to expand and grow in every corner of the world, Portugal is no exception. With the launch of “Golden Visa Scheme”, with the closer diplomatic relationships between China and Portugal, more and more Chinese people are doing business and investment in Portugal, and at the same time, more and more Portuguese companies have more opportunities to cooperate with Chinese companies. However, in the process of doing transnational business, both sides of the companies are facing a huge diversity in terms of business communication, which somehow will create misunderstandings and bring complications, as well as interfere with the working productivity. Therefore, the first part of this report focuses on the explanation of the origins and reasons for the emigration of Chinese citizens to Portugal, the identification of differences between Portuguese and Chinese in the workplace, and the presentation of some cases related to problems and challenges in business communication. The second part of this report will briefly introduce the Portuguese- Chinese Chamber of Commerce and Industry, its mission, social bodies, services, history and its representative events. The last part of this report will describe more specifically my objects, my tasks and work during my four months of internship, also mention some of the important events that I have participated.现今，中国与全球化对大家来说都不陌生，全世界都在强烈地感受着中国经济带来的影响。中国的业务发展正在扩展到全世界的各个角落，葡萄牙也不例外。随着“黄金签证计划” 的实施以及中葡外交关系的日益密切，越来越多的中国人在葡萄牙开展业务和投资。同时，也有越来越多的葡萄牙公司拥有更多的机会与中国公司进行合作。然而，在发展跨国业务的过程中，中葡公司在业务沟通方面却面临着巨大的差异，而这些差异有时会使双方产生误解，或使问题越来越复杂，或影响工作效率。因此，本报告的第一部分将重点分析中国人向葡萄牙移民的起源和原因，中国人和葡萄牙人的工作差异，以及介绍一些在商业交流中出现的问题和挑战的相关案例。 本报告的第二部分将简要介绍葡中工商会，其使命、机构组成、服务、历史及其代表性活动。 本报告的最后一部分将具体地描述本人的实习目标以及为期四个月的实习任务和工作，并简要描述实习期间所参与的一些重要活动

Improving Local Search for Minimum Weighted Connected Dominating Set Problem by Inner-Layer Local Search

The minimum weighted connected dominating set (MWCDS) problem is an important variant of connected dominating set problems with wide applications, especially in heterogenous networks and gene regulatory networks. In the paper, we develop a nested local search algorithm called NestedLS for solving MWCDS on classic benchmarks and massive graphs. In this local search framework, we propose two novel ideas to make it effective by utilizing previous search information. First, we design the restart based smoothing mechanism as a diversification method to escape from local optimal. Second, we propose a novel inner-layer local search method to enlarge the candidate removal set, which can be modelled as an optimized version of spanning tree problem. Moreover, inner-layer local search method is a general method for maintaining the connectivity constraint when dealing with massive graphs. Experimental results show that NestedLS outperforms state-of-the-art meta-heuristic algorithms on most instances

New Characterizations and Efficient Local Search for General Integer Linear Programming

Integer linear programming (ILP) models a wide range of practical combinatorial optimization problems and has significant impacts in industry and management sectors. This work proposes new characterizations of ILP with the concept of boundary solutions. Motivated by the new characterizations, we develop an efficient local search solver, which is the first local search solver for general ILP validated on a large heterogeneous problem dataset. We propose a new local search framework that switches between three modes, namely Search, Improve, and Restore modes. We design tailored operators adapted to different modes, thus improving the quality of the current solution according to different situations. For the Search and Restore modes, we propose an operator named tight move, which adaptively modifies variables' values, trying to make some constraint tight. For the Improve mode, an efficient operator lift move is proposed to improve the quality of the objective function while maintaining feasibility. Putting these together, we develop a local search solver for integer linear programming called Local-ILP. Experiments conducted on the MIPLIB dataset show the effectiveness of our solver in solving large-scale hard integer linear programming problems within a reasonably short time. Local-ILP is competitive and complementary to the state-of-the-art commercial solver Gurobi and significantly outperforms the state-of-the-art non-commercial solver SCIP. Moreover, our solver establishes new records for 6 MIPLIB open instances. The theoretical analysis of our algorithm is also presented, which shows our algorithm could avoid visiting unnecessary regions and also maintain good connectivity of targeted solutions.Comment: 36 pages, 2 figures, 7 table

Improving Local Search for Structured SAT Formulas via Unit Propagation Based Construct and Cut Initialization (Short Paper)

This work is dedicated to improving local search solvers for the Boolean satisfiability (SAT) problem on structured instances. We propose a construct-and-cut (CnC) algorithm based on unit propagation, which is used to produce initial assignments for local search. We integrate our CnC initialization procedure within several state-of-the-art local search SAT solvers, and obtain the improved solvers. Experiments are carried out with a benchmark encoded from a spectrum repacking project as well as benchmarks encoded from two important mathematical problems namely Boolean Pythagorean Triple and Schur Number Five. The experiments show that the CnC initialization improves the local search solvers, leading to better performance than state-of-the-art SAT solvers based on Conflict Driven Clause Learning (CDCL) solvers

Real-Time Marker Localization Learning for GelStereo Tactile Sensing

Visuotactile sensing technology is becoming more popular in tactile sensing, but the effectiveness of the existing marker detection localization methods remains to be further explored. Instead of contour-based blob detection, this paper presents a learning-based marker localization network for GelStereo visuotactile sensing called Marknet. Specifically, the Marknet presents a grid regression architecture to incorporate the distribution of the GelStereo markers. Furthermore, a marker rationality evaluator (MRE) is modelled to screen suitable prediction results. The experimental results show that the Marknet combined with MRE achieves 93.90% precision for irregular markers in contact areas, which outperforms the traditional contour-based blob detection method by a large margin of 42.32%. Meanwhile, the proposed learning-based marker localization method can achieve better real-time performance beyond the blob detection interface provided by the OpenCV library through GPU acceleration, which we believe will lead to considerable perceptual sensitivity gains in various robotic manipulation tasks

A facile approach to fabricate highly sensitive, flexible strain sensor based on elastomeric/graphene platelet composite film

This work developed a facile approach to fabricate highly sensitive and flexible polyurethane/graphene platelets composite film for wearable strain sensor. The composite film was fabricated via layer-by-layer laminating method which is simple and cost-effective; it exhibited outstanding electrical conductivity of 1430 ± 50 S/cm and high sensitivity to strain (the gauge factor is up to 150). In the sensor application test, the flexible strain sensor achieves real-time monitoring accurately for five bio-signals such as pulse movement, finger movement, and cheek movement giving a great potential as wearable-sensing device. In addition, the developed strain sensor shows response to pressure and temperature in a certain region. A multifaceted comparison between reported flexible strain sensors and our strain sensor was made highlighting the advantages of the current work in terms of (1) high sensitivity (gauge factor) and flexibility, (2) facile approach of fabrication, and (3) accurate monitoring for body motions

BAGEL: Backdoor Attacks against Federated Contrastive Learning

Federated Contrastive Learning (FCL) is an emerging privacy-preserving paradigm in distributed learning for unlabeled data. In FCL, distributed parties collaboratively learn a global encoder with unlabeled data, and the global encoder could be widely used as a feature extractor to build models for many downstream tasks. However, FCL is also vulnerable to many security threats (e.g., backdoor attacks) due to its distributed nature, which are seldom investigated in existing solutions. In this paper, we study the backdoor attack against FCL as a pioneer research, to illustrate how backdoor attacks on distributed local clients act on downstream tasks. Specifically, in our system, malicious clients can successfully inject a backdoor into the global encoder by uploading poisoned local updates, thus downstream models built with this global encoder will also inherit the backdoor. We also investigate how to inject backdoors into multiple downstream models, in terms of two different backdoor attacks, namely the \textit{centralized attack} and the \textit{decentralized attack}. Experiment results show that both the centralized and the decentralized attacks can inject backdoors into downstream models effectively with high attack success rates. Finally, we evaluate two defense methods against our proposed backdoor attacks in FCL, which indicates that the decentralized backdoor attack is more stealthy and harder to defend