On determinism versus nondeterminism for restarting automata

AbstractA restarting automaton processes a given word by executing a sequence of local simplifications until a simple word is obtained that the automaton then accepts. Such a computation is expressed as a sequence of cycles. A nondeterministic restarting automaton M is called correctness preserving, if, for each cycle u⊢Mcv, the string v belongs to the characteristic language LC(M) of M, if the string u does. Our first result states that for each type of restarting automaton X∈{R,RW,RWW,RL,RLW,RLWW}, if M is a nondeterministic X-automaton that is correctness preserving, then there exists a deterministic X-automaton M1 such that the characteristic languages LC(M1) and LC(M) coincide. When a restarting automaton M executes a cycle that transforms a string from the language LC(M) into a string not belonging to LC(M), then this can be interpreted as an error of M. By counting the number of cycles it may take M to detect this error, we obtain a measure for the influence that errors have on computations. Accordingly, this measure is called error detection distance. It turns out, however, that an X-automaton with bounded error detection distance is equivalent to a correctness preserving X-automaton, and therewith to a deterministic X-automaton. This means that nondeterminism increases the expressive power of X-automata only in combination with an unbounded error detection distance

26. Theorietag Automaten und Formale Sprachen 23. Jahrestagung Logik in der Informatik: Tagungsband

Der Theorietag ist die Jahrestagung der Fachgruppe Automaten und Formale Sprachen der Gesellschaft für Informatik und fand erstmals 1991 in Magdeburg statt. Seit dem Jahr 1996 wird der Theorietag von einem eintägigen Workshop mit eingeladenen Vorträgen begleitet. Die Jahrestagung der Fachgruppe Logik in der Informatik der Gesellschaft für Informatik fand erstmals 1993 in Leipzig statt. Im Laufe beider Jahrestagungen finden auch die jährliche Fachgruppensitzungen statt. In diesem Jahr wird der Theorietag der Fachgruppe Automaten und Formale Sprachen erstmalig zusammen mit der Jahrestagung der Fachgruppe Logik in der Informatik abgehalten. Organisiert wurde die gemeinsame Veranstaltung von der Arbeitsgruppe Zuverlässige Systeme des Instituts für Informatik an der Christian-Albrechts-Universität Kiel vom 4. bis 7. Oktober im Tagungshotel Tannenfelde bei Neumünster. Während des Tre↵ens wird ein Workshop für alle Interessierten statt finden. In Tannenfelde werden • Christoph Löding (Aachen) • Tomás Masopust (Dresden) • Henning Schnoor (Kiel) • Nicole Schweikardt (Berlin) • Georg Zetzsche (Paris) eingeladene Vorträge zu ihrer aktuellen Arbeit halten. Darüber hinaus werden 26 Vorträge von Teilnehmern und Teilnehmerinnen gehalten, 17 auf dem Theorietag Automaten und formale Sprachen und neun auf der Jahrestagung Logik in der Informatik. Der vorliegende Band enthält Kurzfassungen aller Beiträge. Wir danken der Gesellschaft für Informatik, der Christian-Albrechts-Universität zu Kiel und dem Tagungshotel Tannenfelde für die Unterstützung dieses Theorietags. Ein besonderer Dank geht an das Organisationsteam: Maike Bradler, Philipp Sieweck, Joel Day. Kiel, Oktober 2016 Florin Manea, Dirk Nowotka und Thomas Wilk

For differential equations with r parameters, 2r+1 experiments are enough for identification

Given a set of differential equations whose description involves unknown parameters, such as reaction constants in chemical kinetics, and supposing that one may at any time measure the values of some of the variables and possibly apply external inputs to help excite the system, how many experiments are sufficient in order to obtain all the information that is potentially available about the parameters? This paper shows that the best possible answer (assuming exact measurements) is 2r+1 experiments, where r is the number of parameters.Comment: This is a minor revision of the previously submitted report; a couple of typos have been fixed, and some comments and two new references have been added. Please see http://www.math.rutgers.edu/~sontag for related wor

강인한 대화형 영상 분할 알고리즘을 위한 시드 정보 확장 기법에 대한 연구

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 전기·컴퓨터공학부, 2021. 2. 이경무.Segmentation of an area corresponding to a desired object in an image is essential to computer vision problems. This is because most algorithms are performed in semantic units when interpreting or analyzing images. However, segmenting the desired object from a given image is an ambiguous issue. The target object varies depending on user and purpose. To solve this problem, an interactive segmentation technique has been proposed. In this approach, segmentation was performed in the desired direction according to interaction with the user. In this case, seed information provided by the user plays an important role. If the seed provided by a user contain abundant information, the accuracy of segmentation increases. However, providing rich seed information places much burden on the users. Therefore, the main goal of the present study was to obtain satisfactory segmentation results using simple seed information. We primarily focused on converting the provided sparse seed information to a rich state so that accurate segmentation results can be derived. To this end, a minimum user input was taken and enriched it through various seed enrichment techniques. A total of three interactive segmentation techniques was proposed based on: (1) Seed Expansion, (2) Seed Generation, (3) Seed Attention. Our seed enriching type comprised expansion of area around a seed, generation of new seed in a new position, and attention to semantic information. First, in seed expansion, we expanded the scope of the seed. We integrated reliable pixels around the initial seed into the seed set through an expansion step composed of two stages. Through the extended seed covering a wider area than the initial seed, the seed's scarcity and imbalance problems was resolved. Next, in seed generation, we created a seed at a new point, but not around the seed. We trained the system by imitating the user behavior through providing a new seed point in the erroneous region. By learning the user's intention, our model could e ciently create a new seed point. The generated seed helped segmentation and could be used as additional information for weakly supervised learning. Finally, through seed attention, we put semantic information in the seed. Unlike the previous models, we integrated both the segmentation process and seed enrichment process. We reinforced the seed information by adding semantic information to the seed instead of spatial expansion. The seed information was enriched through mutual attention with feature maps generated during the segmentation process. The proposed models show superiority compared to the existing techniques through various experiments. To note, even with sparse seed information, our proposed seed enrichment technique gave by far more accurate segmentation results than the other existing methods.영상에서 원하는 물체 영역을 잘라내는 것은 컴퓨터 비전 문제에서 필수적인 요소이다. 영상을 해석하거나 분석할 때, 대부분의 알고리즘들이 의미론적인 단위 기반으로 동작하기 때문이다. 그러나 영상에서 물체 영역을 분할하는 것은 모호한 문제이다. 사용자와 목적에 따라 원하는 물체 영역이 달라지기 때문이다. 이를 해결하기 위해 사용자와의 교류를 통해 원하는 방향으로 영상 분할을 진행하는 대화형 영상 분할 기법이 사용된다. 여기서 사용자가 제공하는 시드 정보가 중요한 역할을 한다. 사용자의 의도를 담고 있는 시드 정보가 정확할수록 영상 분할의 정확도도 증가하게 된다. 그러나 풍부한 시드 정보를 제공하는 것은 사용자에게 많은 부담을 주게 된다. 그러므로 간단한 시드 정보를 사용하여 만족할만한 분할 결과를 얻는 것이 주요 목적이 된다. 우리는 제공된 희소한 시드 정보를 변환하는 작업에 초점을 두었다. 만약 시드 정보가 풍부하게 변환된다면 정확한 영상 분할 결과를 얻을 수 있기 때문이다. 그러므로 본 학위 논문에서는 시드 정보를 풍부하게 하는 기법들을 제안한다. 최소한의 사용자 입력을 가정하고 이를 다양한 시드 확장 기법을 통해 변환한다. 우리는 시드 확대, 시드 생성, 시드 주의 집중에 기반한 총 세 가지의 대화형 영상 분할 기법을 제안한다. 각각 시드 주변으로의 영역 확대, 새로운 지점에 시드 생성, 의미론적 정보에 주목하는 형태의 시드 확장 기법을 사용한다. 먼저 시드 확대에 기반한 기법에서 우리는 시드의 영역 확장을 목표로 한다. 두 단계로 구성된 확대 과정을 통해 처음 시드 주변의 비슷한 픽셀들을 시드 영역으로 편입한다. 이렇게 확장된 시드를 사용함으로써 시드의 희소함과 불균형으로 인한 문제를 해결할 수 있다. 다음으로 시드 생성에 기반한 기법에서 우리는 시드 주변이 아닌 새로운 지점에 시드를 생성한다. 우리는 오차가 발생한 영역에 사용자가 새로운 시드를 제공하는 동작을 모방하여 시스템을 학습하였다. 사용자의 의도를 학습함으로써 효과적으로 시드를 생성할 수 있다. 생성된 시드는 영상 분할의 정확도를 높일 뿐만 아니라 약지도학습을 위한 데이터로써 활용될 수 있다. 마지막으로 시드 주의 집중을 활용한 기법에서 우리는 의미론적 정보를 시드에 담는다. 기존에 제안한 기법들과 달리 영상 분할 동작과 시드 확장 동작이 통합된 모델을 제안한다. 시드 정보는 영상 분할 네트워크의 특징맵과 상호 교류하며 그 정보가 풍부해진다. 제안한 모델들은 다양한 실험을 통해 기존 기법 대비 우수한 성능을 기록하였다. 특히 시드가 부족한 상황에서 시드 확장 기법들은 훌륭한 대화형 영상 분할 성능을 보였다.1 Introduction 1 1.1 Previous Works 2 1.2 Proposed Methods 4 2 Interactive Segmentation with Seed Expansion 9 2.1 Introduction 9 2.2 Proposed Method 12 2.2.1 Background 13 2.2.2 Pyramidal RWR 16 2.2.3 Seed Expansion 19 2.2.4 Re nement with Global Information 24 2.3 Experiments 27 2.3.1 Dataset 27 2.3.2 Implement Details 28 2.3.3 Performance 29 2.3.4 Contribution of Each Part 30 2.3.5 Seed Consistency 31 2.3.6 Running Time 33 2.4 Summary 34 3 Interactive Segmentation with Seed Generation 37 3.1 Introduction 37 3.2 Related Works 40 3.3 Proposed Method 41 3.3.1 System Overview 41 3.3.2 Markov Decision Process 42 3.3.3 Deep Q-Network 46 3.3.4 Model Architecture 47 3.4 Experiments 48 3.4.1 Implement Details 48 3.4.2 Performance 49 3.4.3 Ablation Study 53 3.4.4 Other Datasets 55 3.5 Summary 58 4 Interactive Segmentation with Seed Attention 61 4.1 Introduction 61 4.2 Related Works 64 4.3 Proposed Method 65 4.3.1 Interactive Segmentation Network 65 4.3.2 Bi-directional Seed Attention Module 67 4.4 Experiments 70 4.4.1 Datasets 70 4.4.2 Metrics 70 4.4.3 Implement Details 71 4.4.4 Performance 71 4.4.5 Ablation Study 76 4.4.6 Seed enrichment methods 79 4.5 Summary 82 5 Conclusions 87 5.1 Summary 89 Bibliography 90 국문초록 103Docto

Safety and security of cyber-physical systems

The number of embedded controllers in charge of physical systems has rapidly increased over the past years. Embedded controllers are present in every aspect of our lives, from our homes to our vehicles and factories. The complexity of these systems is also more than ever. These systems are expected to deliver many features and high performance without trading off in robustness and assurance. As systems increase in complexity, however, the cost of formally verifying their correctness and eliminating security vulnerabilities can quickly explode. On top of the unintentional bugs and problems, malicious attacks on cyber-physical systems (CPS) can also lead to adverse outcomes on physical plants. Some of the recent attacks on CPS are focused on causing physical damage to the plants or the environment. Such intruders make their way into the system using cyber exploits but then initiate actions that can destabilize and even damage the underlying (physical) systems. Given the reality mentioned above and the reliability standards of the industry, there is a need to embrace new CPS design paradigms where faults and security vulnerabilities are the norms rather than an anomaly. Such imperfections must be assumed to exist in every system and component unless it is formally verified and scanned. Faults and vulnerabilities should be safely handled and the CPS must be able to recover from them at run-time. Our goal in this work is to introduce and investigate a few designs compatible with this paradigm. The architectures and techniques proposed in this dissertation do not rely on the testing and complete system verification. Instead, they enforce safety at the highest level of the system and extend guaranteed safety from a few certified components to the entire system. These solutions are carefully curated to utilize unverified components and provide guaranteed performance