Programmiersprachen und Rechenkonzepte

Seit 1984 veranstaltet die GI-Fachgruppe "Programmiersprachen und Rechenkonzepte" regelmäßig im Frühjahr einen Workshop im Physikzentrum Bad Honnef. Das Treffen dient in erster Linie dem gegenseitigen Kennenlernen, dem Erfahrungsaustausch, der Diskussion und der Vertiefung gegenseitiger Kontakte. In diesem Forum werden Vorträge und Demonstrationen sowohl bereits abgeschlossener als auch noch laufender Arbeiten vorgestellt, unter anderem (aber nicht ausschließlich) zu Themen wie - Sprachen, Sprachparadigmen - Korrektheit von Entwurf und Implementierung - Werkzeuge - Software-/Hardware-Architekturen - Spezifikation, Entwurf - Validierung, Verifikation - Implementierung, Integration - Sicherheit (Safety und Security) - eingebettete Systeme - hardware-nahe Programmierung. In diesem Technischen Bericht sind einige der präsentierten Arbeiten zusammen gestellt

Multilinear Maps in Cryptography

Multilineare Abbildungen spielen in der modernen Kryptographie eine immer bedeutendere Rolle. In dieser Arbeit wird auf die Konstruktion, Anwendung und Verbesserung von multilinearen Abbildungen eingegangen

Statistical natural language processing methods for intelligent process automation

Nowadays, digitization is transforming the way businesses work. Recently, Artificial Intelligence (AI) techniques became an essential part of the automation of business processes: In addition to cost advantages, these techniques offer fast processing times and higher customer satisfaction rates, thus ultimately increasing sales. One of the intelligent approaches for accelerating digital transformation in companies is the Robotic Process Automation (RPA). An RPA-system is a software tool that robotizes routine and time-consuming responsibilities such as email assessment, various calculations, or creation of documents and reports (Mohanty and Vyas, 2018). Its main objective is to organize a smart workflow and therethrough to assist employees by offering them more scope for cognitively demanding and engaging work. Intelligent Process Automation (IPA) offers all these advantages as well; however, it goes beyond the RPA by adding AI components such as Machine- and Deep Learning techniques to conventional automation solutions. Previously, IPA approaches were primarily employed within the computer vision domain. However, in recent times, Natural Language Processing (NLP) became one of the potential applications for IPA as well due to its ability to understand and interpret human language. Usually, NLP methods are used to analyze large amounts of unstructured textual data and to respond to various inquiries. However, one of the central applications of NLP within the IPA domain – are conversational interfaces (e.g., chatbots, virtual agents) that are used to enable human-to-machine communication. Nowadays, conversational agents gain enormous demand due to their ability to support a large number of users simultaneously while communicating in a natural language. The implementation of a conversational agent comprises multiple stages and involves diverse types of NLP sub-tasks, starting with natural language understanding (e.g., intent recognition, named entity extraction) and going towards dialogue management (i.e., determining the next possible bots action) and response generation. Typical dialogue system for IPA purposes undertakes straightforward customer support requests (e.g., FAQs), allowing human workers to focus on more complicated inquiries. In this thesis, we are addressing two potential Intelligent Process Automation (IPA) applications and employing statistical Natural Language Processing (NLP) methods for their implementation. The first block of this thesis (Chapter 2 – Chapter 4) deals with the development of a conversational agent for IPA purposes within the e-learning domain. As already mentioned, chatbots are one of the central applications for the IPA domain since they can effectively perform time-consuming tasks while communicating in a natural language. Within this thesis, we realized the IPA conversational bot that takes care of routine and time-consuming tasks regularly performed by human tutors of an online mathematical course. This bot is deployed in a real-world setting within the OMB+ mathematical platform. Conducting experiments for this part, we observed two possibilities to build the conversational agent in industrial settings – first, with purely rule-based methods, considering the missing training data and individual aspects of the target domain (i.e., e-learning). Second, we re-implemented two of the main system components (i.e., Natural Language Understanding (NLU) and Dialogue Manager (DM) units) using the current state-of-the-art deep-learning architecture (i.e., Bidirectional Encoder Representations from Transformers (BERT)) and investigated their performance and potential use as a part of a hybrid model (i.e., containing both rule-based and machine learning methods). The second part of the thesis (Chapter 5 – Chapter 6) considers an IPA subproblem within the predictive analytics domain and addresses the task of scientific trend forecasting. Predictive analytics forecasts future outcomes based on historical and current data. Therefore, using the benefits of advanced analytics models, an organization can, for instance, reliably determine trends and emerging topics and then manipulate it while making significant business decisions (i.e., investments). In this work, we dealt with the trend detection task – specifically, we addressed the lack of publicly available benchmarks for evaluating trend detection algorithms. We assembled the benchmark for the detection of both scientific trends and downtrends (i.e., topics that become less frequent overtime). To the best of our knowledge, the task of downtrend detection has not been addressed before. The resulting benchmark is based on a collection of more than one million documents, which is among the largest that has been used for trend detection before, and therefore, offers a realistic setting for the development of trend detection algorithms.Robotergesteuerte Prozessautomatisierung (RPA) ist eine Art von Software-Bots, die manuelle menschliche Tätigkeiten wie die Eingabe von Daten in das System, die Anmeldung in Benutzerkonten oder die Ausführung einfacher, aber sich wiederholender Arbeitsabläufe nachahmt (Mohanty and Vyas, 2018). Einer der Hauptvorteile und gleichzeitig Nachteil der RPA-bots ist jedoch deren Fähigkeit, die gestellte Aufgabe punktgenau zu erfüllen. Einerseits ist ein solches System in der Lage, die Aufgabe akkurat, sorgfältig und schnell auszuführen. Andererseits ist es sehr anfällig für Veränderungen in definierten Szenarien. Da der RPA-Bot für eine bestimmte Aufgabe konzipiert ist, ist es oft nicht möglich, ihn an andere Domänen oder sogar für einfache Änderungen in einem Arbeitsablauf anzupassen (Mohanty and Vyas, 2018). Diese Unfähigkeit, sich an veränderte Bedingungen anzupassen, führte zu einem weiteren Verbesserungsbereich für RPAbots – den Intelligenten Prozessautomatisierungssystemen (IPA). IPA-Bots kombinieren RPA mit Künstlicher Intelligenz (AI) und können komplexe und kognitiv anspruchsvollere Aufgaben erfüllen, die u.A. Schlussfolgerungen und natürliches Sprachverständnis erfordern. Diese Systeme übernehmen zeitaufwändige und routinemäßige Aufgaben, ermöglichen somit einen intelligenten Arbeitsablauf und befreien Fachkräfte für die Durchführung komplizierterer Aufgaben. Bisher wurden die IPA-Techniken hauptsächlich im Bereich der Bildverarbeitung eingesetzt. In der letzten Zeit wurde die natürliche Sprachverarbeitung (NLP) jedoch auch zu einem der potenziellen Anwendungen für IPA, und zwar aufgrund von der Fähigkeit, die menschliche Sprache zu interpretieren. NLP-Methoden werden eingesetzt, um große Mengen an Textdaten zu analysieren und auf verschiedene Anfragen zu reagieren. Auch wenn die verfügbaren Daten unstrukturiert sind oder kein vordefiniertes Format haben (z.B. E-Mails), oder wenn die in einem variablen Format vorliegen (z.B. Rechnungen, juristische Dokumente), dann werden ebenfalls die NLP Techniken angewendet, um die relevanten Informationen zu extrahieren, die dann zur Lösung verschiedener Probleme verwendet werden können. NLP im Rahmen von IPA beschränkt sich jedoch nicht auf die Extraktion relevanter Daten aus Textdokumenten. Eine der zentralen Anwendungen von IPA sind Konversationsagenten, die zur Interaktion zwischen Mensch und Maschine eingesetzt werden. Konversationsagenten erfahren enorme Nachfrage, da sie in der Lage sind, eine große Anzahl von Benutzern gleichzeitig zu unterstützen, und dabei in einer natürlichen Sprache kommunizieren. Die Implementierung eines Chatsystems umfasst verschiedene Arten von NLP-Teilaufgaben, beginnend mit dem Verständnis der natürlichen Sprache (z.B. Absichtserkennung, Extraktion von Entitäten) über das Dialogmanagement (z.B. Festlegung der nächstmöglichen Bot-Aktion) bis hin zur Response-Generierung. Ein typisches Dialogsystem für IPA-Zwecke übernimmt in der Regel unkomplizierte Kundendienstanfragen (z.B. Beantwortung von FAQs), so dass sich die Mitarbeiter auf komplexere Anfragen konzentrieren können. Diese Dissertation umfasst zwei Bereiche, die durch das breitere Thema vereint sind, nämlich die Intelligente Prozessautomatisierung (IPA) unter Verwendung statistischer Methoden der natürlichen Sprachverarbeitung (NLP). Der erste Block dieser Arbeit (Kapitel 2 – Kapitel 4) befasst sich mit der Impementierung eines Konversationsagenten für IPA-Zwecke innerhalb der E-Learning-Domäne. Wie bereits erwähnt, sind Chatbots eine der zentralen Anwendungen für die IPA-Domäne, da sie zeitaufwändige Aufgaben in einer natürlichen Sprache effektiv ausführen können. Der IPA-Kommunikationsbot, der in dieser Arbeit realisiert wurde, kümmert sich ebenfalls um routinemäßige und zeitaufwändige Aufgaben, die sonst von Tutoren in einem Online-Mathematikkurs in deutscher Sprache durchgeführt werden. Dieser Bot ist in der täglichen Anwendung innerhalb der mathematischen Plattform OMB+ eingesetzt. Bei der Durchführung von Experimenten beobachteten wir zwei Möglichkeiten, den Konversationsagenten im industriellen Umfeld zu entwickeln – zunächst mit rein regelbasierten Methoden, unter Bedingungen der fehlenden Trainingsdaten und besonderer Aspekte der Zieldomäne (d.h. E-Learning). Zweitens haben wir zwei der Hauptsystemkomponenten (Sprachverständnismodul, Dialog-Manager) mit dem derzeit fortschrittlichsten Deep Learning Algorithmus reimplementiert und die Performanz dieser Komponenten untersucht. Der zweite Teil der Doktorarbeit (Kapitel 5 – Kapitel 6) betrachtet ein IPA-Problem innerhalb des Vorhersageanalytik-Bereichs. Vorhersageanalytik zielt darauf ab, Prognosen über zukünftige Ergebnisse auf der Grundlage von historischen und aktuellen Daten zu erstellen. Daher kann ein Unternehmen mit Hilfe der Vorhersagesysteme z.B. die Trends oder neu entstehende Themen zuverlässig bestimmen und diese Informationen dann bei wichtigen Geschäftsentscheidungen (z.B. Investitionen) einsetzen. In diesem Teil der Arbeit beschäftigen wir uns mit dem Teilproblem der Trendprognose – insbesondere mit dem Fehlen öffentlich zugänglicher Benchmarks für die Evaluierung von Trenderkennungsalgorithmen. Wir haben den Benchmark zusammengestellt und veröffentlicht, um sowohl Trends als auch Abwärtstrends zu erkennen. Nach unserem besten Wissen ist die Aufgabe der Abwärtstrenderkennung bisher nicht adressiert worden. Der resultierende Benchmark basiert auf einer Sammlung von mehr als einer Million Dokumente, der zu den größten gehört, die bisher für die Trenderkennung verwendet wurden, und somit einen realistischen Rahmen für die Entwicklung von Trenddetektionsalgorithmen bietet

Types with potential: polynomial resource bounds via automatic amortized analysis

A primary feature of a computer program is its quantitative performance characteristics: the amount of resources such as time, memory, and power the program needs to perform its task. Concrete resource bounds for specific hardware have many important applications in software development but their manual determination is tedious and error-prone. This dissertation studies the problem of automatically determining concrete worst-case bounds on the quantitative resource consumption of functional programs. Traditionally, automatic resource analyses are based on recurrence relations. The difficulty of both extracting and solving recurrence relations has led to the development of type-based resource analyses that are compositional, modular, and formally verifiable. However, existing automatic analyses based on amortization or sized types can only compute bounds that are linear in the sizes of the arguments of a function. This work presents a novel type system that derives polynomial bounds from first-order functional programs. As pioneered by Hofmann and Jost for linear bounds, it relies on the potential method of amortized analysis. Types are annotated with multivariate resource polynomials, a rich class of functions that generalize non-negative linear combinations of binomial coefficients. The main theorem states that type derivations establish resource bounds that are sound with respect to the resource-consumption of programs which is formalized by a big-step operational semantics. Simple local type rules allow for an efficient inference algorithm for the type annotations which relies on linear constraint solving only. This gives rise to an analysis system that is fully automatic if a maximal degree of the bounding polynomials is given. The analysis is generic in the resource of interest and can derive bounds on time and space usage. The bounds are naturally closed under composition and eventually summarized in closed, easily understood formulas. The practicability of this automatic amortized analysis is verified with a publicly available implementation and a reproducible experimental evaluation. The experiments with a wide range of examples from functional programming show that the inference of the bounds only takes a couple of seconds in most cases. The derived heap-space and evaluation-step bounds are compared with the measured worst-case behavior of the programs. Most bounds are asymptotically tight, and the constant factors are close or even identical to the optimal ones. For the first time we are able to automatically and precisely analyze the resource consumption of involved programs such as quick sort for lists of lists, longest common subsequence via dynamic programming, and multiplication of a list of matrices with different, fitting dimensions

Computational simulation of piezo-electrically stimulated bone adaption surrounding activated teeth implants

[no abstract

The mathematical values of fraction signs in the Linear A script: A computational, statistical and typological approach

Minoan Linear A is still an undeciphered script mainly used for administrative purposes on Bronze Age Crete. One of its most enigmatic features is the precise mathematical values of its system of numerical fractions. The aim of this article is to address this issue through a multi-stranded methodology that comprises palaeographical examination and statistical, computational, and typological approaches. Taking on from previous analyses, which suggested hypothetical values for some fractions, we extended our probe into assessing values for some problematic ones. The results achieved, based, on the one hand, on a close palaeographical analysis and, on the other, on computational, statistical, and typological strategies, show a remarkable convergence and point towards a systematic assignment of mathematical values for the Linear A fraction signs. This contribution sets the agenda for a combinatorial, novel, and unbiased approach that may help advance our comprehension of some standing issues related to ancient undeciphered writing systems

Types with potential: polynomial resource bounds via automatic amortized analysis

A primary feature of a computer program is its quantitative performance characteristics: the amount of resources such as time, memory, and power the program needs to perform its task. Concrete resource bounds for specific hardware have many important applications in software development but their manual determination is tedious and error-prone. This dissertation studies the problem of automatically determining concrete worst-case bounds on the quantitative resource consumption of functional programs. Traditionally, automatic resource analyses are based on recurrence relations. The difficulty of both extracting and solving recurrence relations has led to the development of type-based resource analyses that are compositional, modular, and formally verifiable. However, existing automatic analyses based on amortization or sized types can only compute bounds that are linear in the sizes of the arguments of a function. This work presents a novel type system that derives polynomial bounds from first-order functional programs. As pioneered by Hofmann and Jost for linear bounds, it relies on the potential method of amortized analysis. Types are annotated with multivariate resource polynomials, a rich class of functions that generalize non-negative linear combinations of binomial coefficients. The main theorem states that type derivations establish resource bounds that are sound with respect to the resource-consumption of programs which is formalized by a big-step operational semantics. Simple local type rules allow for an efficient inference algorithm for the type annotations which relies on linear constraint solving only. This gives rise to an analysis system that is fully automatic if a maximal degree of the bounding polynomials is given. The analysis is generic in the resource of interest and can derive bounds on time and space usage. The bounds are naturally closed under composition and eventually summarized in closed, easily understood formulas. The practicability of this automatic amortized analysis is verified with a publicly available implementation and a reproducible experimental evaluation. The experiments with a wide range of examples from functional programming show that the inference of the bounds only takes a couple of seconds in most cases. The derived heap-space and evaluation-step bounds are compared with the measured worst-case behavior of the programs. Most bounds are asymptotically tight, and the constant factors are close or even identical to the optimal ones. For the first time we are able to automatically and precisely analyze the resource consumption of involved programs such as quick sort for lists of lists, longest common subsequence via dynamic programming, and multiplication of a list of matrices with different, fitting dimensions

Numerical treatment of imprecise random fields in non-linear solid mechanics

The quantification and propagation of mixed uncertain material parameters in the context of solid mechanical finite element simulations is studied. While aleatory uncertainties appear in terms of spatial varying parameters, i.e. random fields, the epistemic character is induced by a lack of knowledge regarding the correlation length, which is therefore described by interval values. The concept and description of the resulting imprecise random fields is introduced in detail. The challenges occurring from interval valued correlation lengths are clarified. These include mainly the stochastic dimension, which can become very high under some circumstances, as well as the comparability of different correlation length scenarios with regard to the underlying truncation error of the applied Karhunen-Loève expansion. Additionally, the computation time can increase drastically, if the straightforward and robust double loop approach is applied. Sparse stochastic collocation method and sparse polynomial chaos expansion are studied to reduce the number of required sample evaluations, i.e. the computational cost. To keep the stochastic dimension as low as possible, the random fields are described by Karhunen-Loève expansion, using a modified exponential correlation kernel, which is advantageous in terms of a fast convergence while providing an analytic solution. Still, for small correlation lengths, the investigated approaches are limited by the curse of dimensionality. Furthermore, they turn out to be not suited for non-linear material models. As a straightforward alternative, a decoupled interpolation approach is proposed, offering a practical engineering estimate. For this purpose, the uncertain quantities only need to be propagated as a random variable and deterministically in terms of the mean values. From these results, the so-called absolutely no idea probability box (ani-p-box) can be obtained, bounding the results of the interval valued correlation length being between zero and infinity. The idea is, to interpolate the result of any arbitrary correlation length within this ani-p-box, exploiting prior knowledge about the statistical behaviour of the input random field corresponding to the correlation length. The new approach is studied for one- and two-dimensional random fields. Furthermore, linear and non-linear finite element models are used in terms of linear-elastic or elasto-plastic material laws, the latter including linear hardening. It appears that the approach only works satisfyingly for sufficiently smooth responses but an improvement by considering also higher order statistics is motivated for future research.DFG/SPP 1886/NA330/12-1/E