HoCHC: A Refutationally Complete and Semantically Invariant System of Higher-order Logic Modulo Theories

We present a simple resolution proof system for higher-order constrained Horn clauses (HoCHC) - a system of higher-order logic modulo theories - and prove its soundness and refutational completeness w.r.t. the standard semantics. As corollaries, we obtain the compactness theorem and semi-decidability of HoCHC for semi-decidable background theories, and we prove that HoCHC satisfies a canonical model property. Moreover a variant of the well-known translation from higher-order to 1st-order logic is shown to be sound and complete for HoCHC in standard semantics. We illustrate how to transfer decidability results for (fragments of) 1st-order logic modulo theories to our higher-order setting, using as example the Bernays-Schonfinkel-Ramsey fragment of HoCHC modulo a restricted form of Linear Integer Arithmetic

Electrical switching of antiferromagnetic Mn2_2Au and the role of thermal activation

Electrical manipulation of antiferromagnets with specific symmetries offers the prospect of creating novel, antiferromagnetic spintronic devices. Such devices aim to make use of the insensitivity to external magnetic fields and the ultrafast dynamics at the picosecond timescale intrinsic to antiferromagnets. The possibility to electrically switch antiferromagnets was first predicted for Mn2Au and then experimentally observed in tetragonal CuMnAs. Here, we report on the electrical switching and detection of the Neel order in epitaxial films of Mn2Au. The exponential dependences of the switching amplitude on the current density and the temperature are explained by a macroscopic thermal activation model taking into account the effect of the Joule heating in Hall cross devices and we observe that the thermal activation plays a key role in the reorientation process of the Neel order. Our model analysis shows that the electrically set Neel-state is long-term stable at room temperature, paving the way for practical applications in memory devices.Comment: 8 pages, 6 figure

Fast and correct variational inference for probabilistic programming: Differentiability, reparameterisation and smoothing

Probabilistic programming is an innovative programming paradigm for posing and automatically solving Bayesian inference problems. In this thesis, we study the foundations of fast yet correct inference for probabilistic programming. Many of the most successful inference techniques (e.g. Hamiltonian Monte Carlo or Stochastic Variational Inference) harness gradients of the so-called density function, which therefore needs to be differentiable at least almost everywhere. We resolve a question posed by Hongseok Yang by demonstrating the following: densities of almost surely terminating programs are differentiable almost everywhere. Having established this property necessary for the correctness of gradient-based inference algorithms, we investigate variational inference, which frames posterior inference as an optimisation problem, in more detail. The dominant approach for stochastic optimisation in practice is stochastic gradient descent. In particular, a variant using the so-called reparameterisation gradient estimator exhibits low variance, resulting in fast convergence in a traditional statistics setting. Unfortunately, although having measure 0, discontinuities can compromise the correctness of this approach. Therefore, we propose a smoothed interpretation parameterised by an accuracy coefficient and present type systems establishing technical pre-conditions. Thus, we can prove stochastic gradient descent with the reparameterisation gradient estimator to be correct when applied to the smoothed problem. Besides, via a uniform convergence result, we can solve the original problem up to any error tolerance by choosing an accuracy coefficient suitably. Furthermore, rather than fixing an accuracy coefficient in advance (limiting the quality of the final solution), we propose a novel variant of stochastic gradient descent, Diagonalisation Stochastic Gradient Descent, which progressively enhances the accuracy of the smoothed approximation during optimisation, and we prove convergence to stationary points of the unsmoothed (original) objective. An empirical evaluation reveals benefits of our approaches over the state of the art: our approaches are simple, fast and attain orders of magnitude reduction in work- normalised variance. Besides, Diagonalisation Stochastic Gradient Descent is more stable than standard stochastic gradient descent for a fixed-accuracy smoothing. Finally, we show unbiasedness of the reparameterisation gradient estimator for continuous but non-differentiable models, and we propose a method based on higher-order logic to establish continuity in the presence of conditionals. We provide a sound and complete reduction for verifying continuity of models to a satisfiability problem, and we propose novel efficient randomised decision procedures

Digitalization of business models : impacts and opportunities for the healthcare industry : a multiple case study approach

The purpose of this applied-research project is to understand how digitalized business models can be assessed and analyzed with regard to their success in the broad field of healthcare. Digitalization holds enormous opportunities, but also requires a particular degree of tact and sensitivity concerning business model design. In order to propose specific guidelines for business model design this paper highlights the major dynamics of the digital business ecosystem, like turbulence, disruptiveness and blurred industry boundaries, and describes Omar El Sawy’s VISOR model, with its components Value Proposition, Interface, Service Platform, Organizing Model and Revenue Model. Following this, the main part consists of two case studies, Nike+ and Kinematix, and narrates the stories of one major, incumbent player and of one new entrant, with the purpose to achieve extensive insights on different perspectives of digital business models. Both companies operate in the field of E-health, more specifically running wearables, Nike with a more generic, Kinematix a more sophisticated approach. The main implications drawn from the case studies cover inter-industry partnership choices, the potential of motivational force based on Social Media, the transformation of the patient-caregiver relationship, the barriers to overcome originating from primary healthcare players, as well as specific dynamic and adaptive capabilities. The paper concludes with suggestions to stimulate future research to find solutions and ways to transform healthcare in a more advanced, forward-looking sector.Esta tese tem como objectivo perceber a aplicação de modelos de negócios digitais no sector da saúde e entender o seu sucesso. As oportunidades deste modelo de negócio são várias contudo o seu sucesso na aplicação requer sensibilidade e conhecimento especifico. Este trabalho propõe directrizes para lidar com este tipo de abordagem e realça as principais características deste modelo de negócio como turbulência, perturbações devido a esta nova visão de negócio, fronteiras da Indústria mal definidas e explica o modelo VISOR de Omar El Sawy em todas as suas componentes: Proposição de Valor, Interface, Plataforma de Serviço Modelo de Organização e de Receita. O corpo desta tese analisa os casos de estudo Nike+ e Kinematix descrevendo a história de um primeiro modelo já incumbente e de outro que é recente, respectivamente. Este processo pretende compreender duas estratégias diferentes em modelos de negócio digitais no sector da saúde. Ambas as empresas operam no segmento de E-saúde, especificamente roupa de corrida. Nike adopta uma abordagem mais genérica enquanto Kinematix tem uma abordagem mais específica. A principal implicação do estudo dos casos são parcerias inter-indústria, o potencial das redes socias em factores motivacionais, a transformação da relação paciente-cuidador, as barreiras a ultrapassar provenientes dos fornecedores de cuidados de saúde primários, bem como as dinâmicas e capacidades adaptativas. No fim deste trabalho são enumeradas sugestões para pesquisa académica futura com vista a transformar os cuidados de saúde num sector mais moderno e avançado

Familientradition Hartz IV?

The study addresses the question of how the biographies of people whose families remain in poverty for generations are structured. In addition, it provides detailed insights into the life of families in relation to ALG II and reconstructively traces the individual context of social reproduction of poverty. It turns out that the way the families interviewed deal with poverty depends on a multitude of interwoven biographical structural aspects.Die Untersuchung widmet sich der Frage, wie sich die Biografien von Menschen gestalten, deren Familien über Generationen hinweg in Armut verbleiben. Dazu gibt sie detaillierte Einblicke in das Leben von Familien im ALG II-Bezug und spürt rekonstruktiv den individuellen Zusammenhängen der sozialen Reproduktion von Armut nach. Es zeigt sich, dass die Art und Weise wie die interviewten Familien mit Armut umgehen von einer Vielzahl miteinander verwobener biografischer Strukturaspekt abhängig ist

Familientradition Hartz IV? Soziale Reproduktion von Armut in Familie und Biografie

Die Untersuchung widmet sich der Frage, wie sich die Biografien von Menschen gestalten, deren Familien über Generationen hinweg in Armut verbleiben. Dazu gibt sie detaillierte Einblicke in das Leben von Familien im ALG II-Bezug und spürt rekonstruktiv den individuellen Zusammenhängen der sozialen Reproduktion von Armut nach. Es zeigt sich, dass die Art und Weise wie die interviewten Familien mit Armut umgehen von einer Vielzahl miteinander verwobener biografischer Strukturaspekte abhängig ist

Initial Limit Datalog:a new extensible class of decidable constrained Horn clauses

We present initial limit Datalog, a new extensible class of constrained Horn clauses for which the satisfiability problem is decidable. The class may be viewed as a generalisation to higher-order logic (with a simple restriction on types) of the first-order language limit Datalog Z (a fragment of Datalog modulo linear integer arithmetic), but can be instantiated with any suitable background theory. For example, the fragment is decidable over any countable well-quasi-order with a decidable first-order theory, such as natural number vectors under componentwise linear arithmetic, and words of a bounded, context-free language ordered by the subword relation. Formulas of initial limit Datalog have the property that, under some assumptions on the background theory, their satisfiability can be witnessed by a new kind of term model which we call entwined structures. Whilst the set of all models is typically uncountable, the set of all entwined structures is recursively enumerable, and model checking is decidable

Detecting Dysfluencies in Stuttering Therapy Using wav2vec 2.0

Stuttering is a varied speech disorder that harms an individual's communication ability. Persons who stutter (PWS) often use speech therapy to cope with their condition. Improving speech recognition systems for people with such non-typical speech or tracking the effectiveness of speech therapy would require systems that can detect dysfluencies while at the same time being able to detect speech techniques acquired in therapy. This paper shows that fine-tuning wav2vec 2.0 [1] for the classification of stuttering on a sizeable English corpus containing stuttered speech, in conjunction with multi-task learning, boosts the effectiveness of the general-purpose wav2vec 2.0 features for detecting stuttering in speech; both within and across languages. We evaluate our method on FluencyBank , [2] and the German therapy-centric Kassel State of Fluency (KSoF) [3] dataset by training Support Vector Machine classifiers using features extracted from the finetuned models for six different stuttering-related event types: blocks, prolongations, sound repetitions, word repetitions, interjections, and - specific to therapy - speech modifications. Using embeddings from the fine-tuned models leads to relative classification performance gains up to 27% w.r.t. F1-score.Comment: Accepted at Interspeech 202

Benefits of the Person-Oriented Perspective for Program Evaluation: Analyzing the Differential Treatment Effects of the Vienna E-Lecturing Program

Background: In program evaluation interventions are usually examined for global effects but not always for differential effects. The reasoning behind the focus on global effects is that most of the concepts applied in data analyses, and most of the hypotheses being assessed, are variable-oriented. Consequently, existing differential effects will not be detected through global analyses based on a variable-oriented perspective. Accordingly, the intervention under evaluation will be wrongly considered to be ineffective. Purpose: This contribution, therefore, argues for the application of person-oriented analyses in addition to the common variable-oriented approach in order to identify the differential effects of an intervention during evaluation. Setting: Both approaches will be applied in the evaluation of a showcase program conducted in real life setting. The results of the two perspectives will be compared. Intervention: An internet supported program for the promotion of self-regulated learning in an academic context called Vienna E-Lecturing (VEL). Research Design: The evaluation of the VEL was conducted with a treatment-control-design. Data was collected at the beginning as well as at the end of the intervention. Data Collection and Analysis: Data regarding motivation as well as factual knowledge was collected. All motivational variables were assessed using previously published scales consisting of 3-4 items. Factual knowledge in statistics and methodology was tested regarding the aspects of reproduction, comprehension and the production of methodological content. Findings: The application of a variable-oriented perspective showed small effects with low practical relevance. Through the application of a person-oriented approach, and taking into account the theoretical framework of the intervention, three students groups which differed systematically in their learning motivation could be identified. For two of these groups the intervention was very successful. The discussion provides recommendations on how person-oriented approaches can be used systematically in program evaluation.  Keywords: person-oriented approach; program evaluation; differential effects; learning motivation; variable-oriented approach; academic contex