O desenvolvimento de redes veiculares possibilita o surgimento de sistemas inteligentes de transporte que podem aumentar a segurança nas vias, aperfeiçoar o controle de tráfego e fornecer entretenimento aos passageiros. O avanço e padronização de tecnologias de comunicação inter-veicular permitem que veículos compartilhem informações de forma colaborativa de maneira a viabilizar o estabelecimento de sistemas de transporte inteligentes cooperativos (C-ITS, Cooperative Intelligent Transportation Systems). Na comunicação veicular, cada nó compartilha periodicamente uma mensagem que contém informações sobre seu estado como posição, velocidade e aceleração. Estas mensagens são denominadas Cooperative Awareness Messages (CAMs) e podem ser utilizadas por veículos vizinhos para a operação de aplicações, sendo a formação de comboios um exemplo. Em um comboio veicular, um grupo de veículos viaja com distância reduzida entre cada membro através da operação de um controlador que utiliza informações compartilhadas por CAMs. O posicionamento compartilhado através de CAMs por cada veículo é crucial para a operação dos controladores de nós vizinhos, dado que este será utilizado para a condução do veículo. Embora os controles criptográficos padronizados para troca de mensagens em VANETs ofereçam contramedidas contra ataques como roubo de identidade e adulteração de pacotes, um atacante interno que possua credenciais válidas do sistema ainda pode mentir sobre as informações que são transmitidas para outros veículos. Em modelos atuais de redes veiculares, cada veículo é responsável por obter sua localização, normalmente através de GPS (Global Positioning System). A dependência de aplicações VANET na posição correta dos nós introduz a necessidade de mecanismos de garantia de localização. Nesta dissertação são identificados os riscos associados com a falsificação de posição em comboios veiculares. Através de simulações utilizando o ambiente de simulação Veins, mostramos que colisões em alta velocidade podem ser causadas por nós que atuam em conluio na falsificação de mensagens para um comboio. Dado que posicionamento legítimo é essencial para o funcionamento adequado das aplicações VANET, investigamos mecanismos de prova de localização propostos na literatura. Então, projetamos um mecanismo de prova de localização adaptado para VANETs usando equipamentos de estrada (RSUs, roadside units), com a capacidade de usar diferentes freqüências de prova de acordo com os requisitos de precisão de detecção e sobrecarga. Através de simulações usando os ataques estudados neste trabalho, mostramos que o mecanismo pode detectar ataques de falsificação de mensagens e Sybil. / In vehicular communication, nodes periodically share Cooperative Awareness Messages (CAMs) in order to convey information such as identity, velocity, acceleration and position. The positioning of nodes in a vehicular network is a key factor that directly affects how applications operate, being the formation of platoons a major case. In vehicular platooning, a group of vehicles travels closely together and leverages information shared through CAMs to operate lateral and longitudinal control algorithms. While the standardised cryptographic mechanisms counteract threats such as identity hijacking and packet tampering, an internal member who holds valid credentials may still be able to lie about the data it transmits in CAMs. In current Vehicular ad hoc Network (VANET) models, each vehicle is responsible for determining and informing its own position, generally using a Global Navigation Satellite System (GNSS) such as the Global Positioning System (GPS). This allows malicious actors to lie about their position and therefore cause unwanted effects in vehicular applications. The dependence of VANET applications on correct node localization introduces the need for position assurance mechanisms. In this dissertation, we first identify the risks associated with falsifying the position in vehicular platooning. Through simulations using the Veins framework, we show that collisions at high speed on a platoon may be caused by nodes that collude in falsification attacks. Given that truthful positioning is essential to proper behavior of VANET applications, we investigate proof-of-location schemes proposed in the literature. Then, a proof-of-location mechanism tailored for VANETs is designed using roadside units, with the capability of using different proof frequencies according to detection accuracy and overhead requirements. Through simulations using the studied attacks in this work, we show that the mechanism can counteract Sybil and message falsification attacks.

Made available in DSpace on 2016-04-26T20:23:16Z (GMT). No. of bitstreams: 1 Eduardo Scalon.pdf: 816996 bytes, checksum: 9393185a1530816c67be01ca3bd0d669 (MD5) Previous issue date: 2014-09-19 / The promulgation of the Code of Consumer Protection in Brazil represented a real change in how legal relationships were assessed and protected. Previously, the concepts of obligation and civil liability were oriented by private law, under the Civil Code, with classic and entrenched concepts as the autonomy of the mutual agreement in legal relations. The CDC greatly alter these concepts to determine that a particular legal relationship, consumer transaction, will be tutored directly by special rules and oriented to the protection and preservation of the rights and interests of one part of the relationship. This guidance, at first, could be configured as a violation of the principle of equal protection. However, the focus of the new rules is precisely the recognition of the need for greater consumer protection, in order to balance their relation with suppliers. This new concept challenged from law schools whose legal education has always been oriented by a dichotomy between public and private laws, as well as jurists and lawyers and judges. The acknowledgement of the new guidance that rules the relations of consumers demands a serious reflection of how apply this new protective law. Careless application of the new rules would transform this important improvement into just a way to jeopardize suppliers. These changes of the consumer protective law require a careful interpretation of several laws and the extent of his apparent collision so that conclusions they reach the scope of the balance between the parties is obtained / A promulgação do Código de Defesa do Consumidor no Brasil representou uma verdadeira quebra de paradgima na forma como as relações jurídicas eram avaliadas e tuteladas. Anteriormente, os conceitos de obrigação e responsabilidade eram orientados pelo Direito Privado, nos termos do Código Civil, com conceitos clássicos e arraigados como a autonomia das partes nas relações jurídicas. O CDC altera sobremaneira tais conceitos ao determinar que uma relação jurídica específica, relação de consumo, será tutelada diretamente por regras especiais e orientadas para a proteção e preservação dos direitos e interesses de uma das partes da relação. Essa orientação, em primeira análise, poderia se configurar como violação ao princípio da isonomia. Todavia, o foco das novas regras é justamente o reconhecimento da necessidade de maior proteção ao consumidor, justamente para equilibrar sua relação com os fornecedores. Esse novo conceito desafiou desde as faculdades cujo ensino jurídico sempre foi pautado pela dicotomia entre direito público e privado, como também os operadores do direito como advogados e juízes. A constatação da nova orientação que governa as relações de consumo demanda uma séria e cuidadosa reflexão de como se operacionaliza essa nova norma protetiva. O manejo descuidado das novas regras levaria esse importante avanço conceitual a uma maneira de prejudicar fornecedores. As alterações determinadas na tutela judicial dos direitos do consumidor obrigam a cuidadosa interpretação conjunta de várias legislações, na medida de sua aparente colisão, para que sejam obtidas conclusões que atinjam o escopo do equilíbrio entre as partes

Dans les coulisses des compétitions handisports de haut-niveau se déroule une épreuve inaccessible au regard du public : le processus de classification. L’expertise, impérative pour attribuer une classe à chaque sportif se matérialise par une série d’opérations effectuées aussi bien par les classificateurs que par les principaux protagonistes : observer, mesurer, quantifier, qualifier, comparer, protester, délibérer… Cette quête d’objectivité s’organise dans plusieurs arènes (vestiaires, Bureau Exécutif du Comité International Paralympique, Commission de Classification, laboratoires). Mais l’impression de stabilité du dispositif contraste avec les témoignages et les observations visant les protocoles d’examen des corps. Les dirigeants cherchent donc à entretenir l’intérêt de la compétition pour les pratiquants et les spectateurs. La complexité du processus apparaît comme un polyptyque évolutif dans lequel les acteurs tentent de mettre de l’ordre et dont le sociologue s’attache à rassembler les pièces éparpillées, tel un commissaire d’exposition.La recherche du langage sociologique le plus approprié permet d’analyser l’adoption, l’entretien, ou l’abandon de la croyance dans l’efficacité du dispositif dont l’enjeu final est la crédibilité des Jeux Paralympiques. Comment est rendue possible et acceptable la mise en équivalence de sportifs aux corps uniques ? Comment les acteurs œuvrent à transformer ou à maintenir en l’état un dispositif qui sépare des individus en même temps qu’il les regroupe? L’enquête permet de comprendre les conditions d’existence du handisport et du sport adapté de compétition et contribue à la réflexion sur les frontières entre les individus. / Backstage of disabled sports competitions high-level event takes place an inaccessible trial to public sight : the classification process. Expertise, imperative to assign a class to each athlete is materialized by a series of operations performed by both classifiers and the main protagonists: observe, measure, quantify, qualify, compare, protest, deliberate ... This quest for objectivity is organized in several arenas (locker rooms, the Executive Board of the International Paralympic Committee, Committee on Classification, laboratories). But the impression of stability of the device contrast with testimonies and observations criticizing the review body protocols. Therefore, institutional leaders are seeking to maintain the interest of competition for practitioners and spectators. The complexity of the process appears to be an evolving polyptych in which actors attempt to bring order and that sociologist try to reassemble the pieces scattered, like a curator. The search for the most appropriate sociological language use to analyze the adoption, maintenance, or abandonment of the belief in the effectiveness of the device whose final issue is the credibility of the Paralympic Games. How is possible and acceptable equity with so unique sports body? How actors work to transform or maintain a device that separate or aggregate individuals in the same time? The survey allows us to understand the conditions of disable sport and adapted sport competition and contributes to the debate on the boundaries between individuals.

Cette thèse expose nos travaux de certification d'une partie d'un programme C/C++ nommé SimSoC (Simulation of System on Chip), qui simule le comportement d'architectures basées sur des processeurs tels que ARM, PowerPC, MIPS ou SH4. Un simulateur de System on Chip peut être utilisé pour developper le logiciel d'un système embarqué spécifique, afin de raccourcir les phases des développement et de test, en particulier quand la vitesse de simulation est réaliste (environ 100 millions d'instructions par seconde par cœur dans le cas de SimSoC). Les réductions de temps et de coût de développement obtenues se traduisent par des cycles de conception interactifs et rapides, en évitant la lourdeur d'un système de développement matériel. SimSoC est un logiciel complexe, comprenant environ 60 000 de C++, intégrant des parties écrites en SystemC et des optimisations non triviales pour atteindre une grande vitesse de simulation. La partie de SimSoC dédiée au processeur ARM, l'un des plus répandus dans le domaine des SoC, transcrit les informations contenus dans un manuel épais de plus de 1000 pages. Les erreurs sont inévitables à ce niveau de complexité, et certaines sont passées au travers des tests intensifs effectués sur la version précédente de SimSoC pour l'ARMv5, qui réussissait tout de même à simuler l'amorçage complet de linux. Un problème critique se pose alors : le simulateur simule-t-il effectivement le matériel réel ? Pour apporter des éléments de réponse positifs à cette question, notre travail vise à prouver la correction d'une partie significative de SimSoC, de sorte à augmenter la confiance de l'utilisateur en ce similateur notamment pour des systèmes critiques. Nous avons concentré nos efforts sur un composant particulièrement sensible de SimSoC : le simulateur du jeu d'instructions de l'ARMv6, faisant partie de la version actuelle de SimSoC. Les approches basées sur une sémantique axiomatique (logique de Hoare par ex- emple) sont les plus répandues en preuve de programmes impératifs. Cependant, nous avons préféré essayer une approche moins classique mais plus directe, basée sur la sémantique opérationnelle de C : cela était rendu possible en théorie depuis la formalisation en Coq d'une telle sémantique au sein du projet CompCert et mettait à notre disposition toute la puissance de Coq pour gérer la complexitité de la spécification. À notre connaissance, au delà de la certification d'un simulateur, il s'agit de la première expérience de preuve de correction de programmes C à cette échelle basée sur la sémantique opérationnelle. Nous définissons une représentation du jeu d'instruction ARM et de ses modes d'adressage formalisée en Coq, grâce à un générateur automatique prenant en entrée le pseudo-code des instructions issu du manuel de référence ARM. Nous générons également l'arbre syntaxique abstrait CompCert du code C simulant les mêmes instructions au sein de Simlight, une version allégée de SimSoC. À partir de ces deux représentations Coq, nous pouvons énoncer et démontrer la correction de Simlight, en nous appuyant sur la sémantique opérationnelle définie dans CompCert. Cette méthodologie a été appliquée à au moins une instruction de chaque catégorie du jeu d'instruction de l'ARM. Au passage, nous avons amélioré la technologie disponible en Coq pour effectuer des inversions, une forme de raisonnement utilisée intensivement dans ce type de situation. / Approaches based on axiomatic semantics (typically, Hoare logic) are the mostpopular for proving the correctness of imperative programs. However, we prefered totry a less usual but more direct approach, based on operational semantics : this wasmade possible in theory since the development of an operational semantics for theC language formalized in Coq in the CompCert project, and allowed us to use thecomfortable logic of Coq, of much help for managing the complexity of the specification.Up to our knowledge, this is the first development of formal correctness proofs basedon operational semantics, at least at this scale.We provide a formalized representation of the ARM instruction set and addressingmodes in Coq, using an automatic code generator from the instruction pseudo-code inthe ARM reference manual. We also generate a Coq representation of a correspondingsimulator in C, called Simlight, using the abstract syntax defined in CompCert.From these two Coq representations, we can then state and prove the correctnessof Simlight, using the operational semantics of C provided by CompCert. Currently,proofs are available for at least one instruction in each category of the ARM instructionset.During this work, we improved the technology available in Coq for performinginversions, a kind of proof steps which heavily occurs in our setting.

Sistemas digitais tornaram-se onipresentes, há cerca de um bilhão de computadores conectados à Internet, e essenciais às atividades humanas. Em consequência, aumentam os casos judiciais cuja solução depende do exame forense de dispositivos eletrônicos. A investigação de ilícitos é quase sempre presencial: oficiais de justiça e peritos coletam computadores suspeitos e os conduzem para laboratórios especializados mantidos pelo Estado (Institutos de Criminalística), por universidades ou pelos próprios peritos judiciais. Funcionários públicos ou especialistas nomeados pelos Juízes e, quando admissíveis, representantes dos autores e réus, conduzem exames técnicos segundo métodos e ferramentas forenses. O resultado é submetido ao Magistrado na forma de um laudo pericial cuja qualidade tem severa repercussão social por ser elemento de convencimento, decisão e julgamento nos processos judiciais. Essa qualidade é ameaçada pela demanda superior aos recursos disponíveis e pela crescente complexidade. Poucos centros de estudo reúnem recursos e competência apropriados ao desafio, além de quase sempre estarem distantes dos seus principais usuários: milhares de fóruns e delegacias espalhados pelo país. Impõe-se, portanto, que os meios acadêmicos lancem mão das mais recentes descobertas científicas para trazer inovações compatíveis com as novas demandas sociais. Uma das mais promissoras tecnologias nesse sentido é o laboratório acessível remotamente via internet, denominado WebLab, no Brasil alvo do projeto KyaTera, coordenado pela Fapesp. A presente dissertação explora e contextualiza esses temas e faz análise preliminar sobre uma alternativa que poderia, dependendo de estudos complementares futuros, proporcionar aos operadores do Direito, como juízes, peritos oficiais e assistentes técnicos das partes, acesso remoto a laboratórios especializados no exame de sistemas eletrônicos digitais e à sociedade uma ferramenta para tornar mais confiáveis os procedimentos periciais forenses. / Digital systems have become ubiquitous, there are nearly a billion computers connected to Internet, and essential for human activities. This leads to the increase of the number of legal cases whose solution depends on the forensic examination of electronic devices. The investigation of unlawful acts is almost always made on site: bailiffs and experts witness collect suspect computers and take them to specialized laboratories maintained by the governments (criminology institutes), universities or even by expert witnesses. Experts appointed by judges and, if eligible, representatives of the defendants and plaintiffs, conducts technical examinations based on forensic methods and tools. The result of this work is submitted to the Judge as an expert witness report whose quality has severe social repercussions as a matter of conviction and decision in the trial proceedings. This quality is under serious threat due to demand greater than available resources and due to growing complexity. Few centers of study have resources and enough technical skill enough to overcome these challenges, and those centers are often distant from users: thousands of courts and police stations throughout Brazil. It is really necessary the academic community engagement to bring solutions to those new social demands by means of latest scientific findings. One of the most promising technologies in this area is an Internet remotely accessible laboratory, using so called WebLab technology, in Brazil developed mainly by the Fapesp project KyaTera. This dissertation explores and contextualizes these themes and makes a preliminary analysis about an alternative which, depending on future complementary studies, may offer to legal professionals and especially to experts and technical assistants remote access to specialized laboratories for the examination of electronic digital systems, providing a tool to society that makes forensic exams more reliable.

Sistemas digitais tornaram-se onipresentes, há cerca de um bilhão de computadores conectados à Internet, e essenciais às atividades humanas. Em consequência, aumentam os casos judiciais cuja solução depende do exame forense de dispositivos eletrônicos. A investigação de ilícitos é quase sempre presencial: oficiais de justiça e peritos coletam computadores suspeitos e os conduzem para laboratórios especializados mantidos pelo Estado (Institutos de Criminalística), por universidades ou pelos próprios peritos judiciais. Funcionários públicos ou especialistas nomeados pelos Juízes e, quando admissíveis, representantes dos autores e réus, conduzem exames técnicos segundo métodos e ferramentas forenses. O resultado é submetido ao Magistrado na forma de um laudo pericial cuja qualidade tem severa repercussão social por ser elemento de convencimento, decisão e julgamento nos processos judiciais. Essa qualidade é ameaçada pela demanda superior aos recursos disponíveis e pela crescente complexidade. Poucos centros de estudo reúnem recursos e competência apropriados ao desafio, além de quase sempre estarem distantes dos seus principais usuários: milhares de fóruns e delegacias espalhados pelo país. Impõe-se, portanto, que os meios acadêmicos lancem mão das mais recentes descobertas científicas para trazer inovações compatíveis com as novas demandas sociais. Uma das mais promissoras tecnologias nesse sentido é o laboratório acessível remotamente via internet, denominado WebLab, no Brasil alvo do projeto KyaTera, coordenado pela Fapesp. A presente dissertação explora e contextualiza esses temas e faz análise preliminar sobre uma alternativa que poderia, dependendo de estudos complementares futuros, proporcionar aos operadores do Direito, como juízes, peritos oficiais e assistentes técnicos das partes, acesso remoto a laboratórios especializados no exame de sistemas eletrônicos digitais e à sociedade uma ferramenta para tornar mais confiáveis os procedimentos periciais forenses. / Digital systems have become ubiquitous, there are nearly a billion computers connected to Internet, and essential for human activities. This leads to the increase of the number of legal cases whose solution depends on the forensic examination of electronic devices. The investigation of unlawful acts is almost always made on site: bailiffs and experts witness collect suspect computers and take them to specialized laboratories maintained by the governments (criminology institutes), universities or even by expert witnesses. Experts appointed by judges and, if eligible, representatives of the defendants and plaintiffs, conducts technical examinations based on forensic methods and tools. The result of this work is submitted to the Judge as an expert witness report whose quality has severe social repercussions as a matter of conviction and decision in the trial proceedings. This quality is under serious threat due to demand greater than available resources and due to growing complexity. Few centers of study have resources and enough technical skill enough to overcome these challenges, and those centers are often distant from users: thousands of courts and police stations throughout Brazil. It is really necessary the academic community engagement to bring solutions to those new social demands by means of latest scientific findings. One of the most promising technologies in this area is an Internet remotely accessible laboratory, using so called WebLab technology, in Brazil developed mainly by the Fapesp project KyaTera. This dissertation explores and contextualizes these themes and makes a preliminary analysis about an alternative which, depending on future complementary studies, may offer to legal professionals and especially to experts and technical assistants remote access to specialized laboratories for the examination of electronic digital systems, providing a tool to society that makes forensic exams more reliable.

Bien que non répertorié dans le code civil au titres des modes de preuve admissibles, le constat d'huissier de justice n'en demeure pas moins un outil de référence dans l'établissement de la preuve des faits juridiques. La souplesse de son régime, à laquelle participe notamment la liberté dévolue au constatant dans la relation matérielle, en fait un procédé probatoire malléalble, adapté aux situations les plus diverses. Instrument de prévention des litiges, voire de règlement anticipé de ces derniers, le constat peut aussi permettre au plaideur de satisfaire à la charge processuelle qui lui incombe de rapporter la preuve des faits au soutien de ses prétentions. A cet égard, il constitue assurément un moyen de réalisation du droit à la preuve, entendu comme celui d'imposer au juge une offre ou une demande de preuve présentant un intérêt probatoire légitime et récemment consacré par la jurisprudence sur le fondement de l'article 6 de la Convention européenne des droits de l'homme. L'absence de carcan juridique enfermant la réalisation de la mesure de constat pourrait cependant faire douter de la qualité de celle-ci. L'allégation mérite d'être éprouvée au regard de la qualité particulière de son auteur. Indifférent à la règlementation sporadique de la mesure, l'huissier de justice en garantit une réalisation licite, respectueuse des principes directeurs du procès et des droits subjectifs des tiers. Le renforcement en matière civile de la valeur probante des constatations établies par cet officier ministériel est à ce titre une confirmation officielle de leur qualité indiscutable. / Although not listed in the civil code in conformance with the approved modes of evidences, the statement of ofacts drawn up by a judicial officer is still a reference tool in the establishment of the proof of legal facts. The flexibility of its regime, in which participates in particular the freedom devolved in the material relation, makes it a probationary process moldable, adapted to the most diverse situations. Instrument of prevention of the disputes, or of their advance settlement, the statement of facts can also allow the litigant to satisfy the procedural burden which falls to him to prove the facts to the support of its claims. In this respect, it serves undoubtedly as a means of realization of the right to evidence, settled as the right to impose to the judge an offer or a request of evidence that hold a legitimate probative interest and recently confirmed by case-law on the basis of the Article 6 of the European Convention on Human Rights. The absence of legal straightjacke locking the establishment of the statement of facts could however raise doubts about its quality. This allegation deserves to be felt with regard to the particular quality of the judicial officer. Indifferent to the sporadic regulations of the measure, he guarantees its lawful realization according to the general principles of the trial and the subjective rights third parties. The strengthening in civil maters of the probative value of the findings made by the judicial officer is as such an official confirmation of their indisputable quality.

Abstract not available

Mammalian pests are excluded from Maungatautari Ecological Island by an XcluderTM pest-proof fence. Inevitably, the fence integrity will be compromised at some point by mechanisms such as treefall and flood-scour: such events could lead to pest re-invasion. Knowledge of pest activity directly outside the reserve would assist reserve managers in developing optimal breach-response procedures. This thesis described baseline data on the presence, timing of activity and behaviour of mammalian pest animals found directly at the Maungatautari fence. Two seasonal video studies investigated the effects of season (summer and winter), exterior habitat (forest and pasture) and simulated breach type ('tree-fall' and 'flood scour') on the number of pest sightings. Significantly more sightings were recorded in summer (788) than in winter (428), particularly for rodents. Rabbits were sighted significantly more often at pasture sites, but habitat type did not significantly affect sightings of any other species; nor did breach type affect sightings of any species. Ship rats were commonly sighted within the fence hood gutter. Overall, rodent, possum and cat sightings were very high, and mustelid sightings extremely low, in both seasons. Over 95% of non-lagomorph sightings were nocturnal, and the greatest threat of invasion was found to come nocturnally, from mice, and in the summer. A probability model showed that although the cumulative probability of a mammalian pest encountering a fence breach increases dramatically after dark, in reality there is always a threat of encounter, and this is always increasing with time. Over the same two studies, the behaviour of pest mammals sighted was also described. Pests were found to show interest in and enter summer breaches more often than winter breaches (p lt 0.001). Simulated breaches were encountered by pests within the first 24 hours at a very high rate (95% summer, 92.5% winter), and most likely to enter a breach were rodents. Over 7 days, breaches were encountered and entered by increasing numbers of species and possibly by more individuals; all species were shown to be willing to enter. The threat of invasion by ship rats was probably underestimated because of their higher activity within the fence hood than at the fence base; mustelids may also offer a greater threat than the results suggest, because they almost always entered a breach. It was strongly recommended that when the fence integrity is compromised, physical response should be as quick as possible, especially at night. Future research was strongly encouraged, particularly to understand invasion behaviour of animals such as ship rats and stoats, and to describe pest behaviour at real breach events.

本文所討論的是開票一路領先問題。假設有A、B兩位候選人，開票結果A得m票、B得n票，開票過程中A的票數一路領先B的票數，我們將開票過程建立在平面的方格上，由(0,0)開始，A得1票記錄成向量(1,0)，B得1票記錄成向量(0,1)，分解成路徑後，A一路領先的開票方法數，就是對角線下的全部路徑數。但是算式及轉換步驟有點複雜，所以我們希望能建構一種簡單的模型對應來解決這個問題。 本文找出A至少一路領先m票的方法數，會對應到m×n的全部路徑走法，最後證明這樣的對應是一對一且映成，並猜想若有多位候選人，其中一人一路領先其他候選人的開票過程，也會有相似的對應方法。 / Suppose A and B are candidates for all election. A receives m votes and B receives n votes. If A stays ahead of B as the ballots are counted, we can think of a ballot permutation as a lattice path starting at (0,0), where votes for A are expressed as east (1,0) and votes for B are expressed as north (0,1). How to calculate the number of paths that A is always in the lead? We just count these paths from (0,0) to (m,n) that are under or touch the diagonal. However, the formula of combinatorial mathematics is not easy to obtain. So we hope to construct a model to resolve this problem. In this paper, we establish a one-to-one correspondence. The ways of A to receive at least m votes are always ahead the same as counting paths from (0,0) to (m,n). Finally, we find a bijective proof in the ballot problem. If there are many candidates, it will be a similar correspondence of one candidate leading the others.