University of Passau

It is well-known that coupling constraints in linear bilevel optimization can lead to disconnected feasible sets, which is not possible without coupling constraints. However, there is no difference between linear bilevel problems with and without coupling constraints w.r.t. their complexity-theoretical hardness. In this note, we prove that, although there is a clear difference between these two classes of problems in terms of their feasible sets, the classes are equivalent on the level of optimal solutions. To this end, given a general linear bilevel problem with coupling constraints, we derive a respective problem without coupling constraints and prove that it has the same optimal solutions (when projected back to the original variable space).

A graph G is q - Ramsey for another graph H if in any q -edge-colouring of G there is a monochromatic copy of H , and the classic Ramsey problem asks for the minimum number of vertices in such a graph. This was broadened in the seminal work of Burr, Erdős, and Lovász to the investigation of other extremal parameters of Ramsey graphs, including the minimum degree. It is not hard to see that if G is minimally q -Ramsey for H we must have $\delta (G) \ge q(\delta (H) - 1) + 1$ , and we say that a graph H is q - Ramsey simple if this bound can be attained. Grinshpun showed that this is typical of rather sparse graphs, proving that the random graph G(n,p) is almost surely 2 -Ramsey simple when $\frac{\log n}{n} \ll p \ll n^{-2/3}$ . In this paper, we explore this question further, asking for which pairs $p = p(n)$ and $q = q(n,p)$ we can expect G(n,p) to be q -Ramsey simple. We first extend Grinshpun’s result by showing that G(n,p) is not just 2 -Ramsey simple, but is in fact q -Ramsey simple for any $q = q(n)$ , provided $p \ll n^{-1}$ or $\frac{\log n}{n} \ll p \ll n^{-2/3}$ . Next, when $p \gg \left ( \frac{\log n}{n} \right )^{1/2}$ , we find that G(n,p) is not q -Ramsey simple for any $q \ge 2$ . Finally, we uncover some interesting behaviour for intermediate edge probabilities. When $n^{-2/3} \ll p \ll n^{-1/2}$ , we find that there is some finite threshold $\tilde{q} = \tilde{q}(H)$ , depending on the structure of the instance $H \sim G(n,p)$ of the random graph, such that H is q -Ramsey simple if and only if $q \le \tilde{q}$ . Aside from a couple of logarithmic factors, this resolves the qualitative nature of the Ramsey simplicity of the random graph over the full spectrum of edge probabilities.

Based on various representative examples, this article shows which images of the “Ingenieur” (engineer) appear in narratives written in German, focusing on the years 1900 to 1930. While a general type of engineers appears as a representative of progress and a hallmark of the time, incorporating this conception as the norm, three further models can be identified, which are embedded within conflicting constellations of normality/deviation, daily routine/emotional emphasis, and the collective/individual: the engineer as a figure who mediates the crossing of borders, the engineer as a condensation of a life felt to be deficient, the engineer as the savior of the world.

Algorithms are capable of advising human decision‐makers in an increasing number of management accounting tasks such as business forecasts. Due to expected potential of these (intelligent) algorithms, there are growing research efforts to explore ways how to boost algorithmic advice usage in forecasting tasks. However, algorithmic advice can also be erroneous. Yet, the risk of using relatively bad advice is largely ignored in this research stream. Therefore, we conduct two online experiments to examine this risk of using relatively bad advice in a forecasting task. In Experiment 1, we examine the influence of performance feedback (revealing previous relative advice quality) and source of advice on advice usage in business forecasts. The results indicate that the provision of performance feedback increases subsequent advice usage but also the usage of subsequent relatively bad advice. In Experiment 2, we investigate whether advice representation, that is, displaying forecast intervals instead of a point estimate, helps to calibrate advice usage towards relative advice quality. The results suggest that advice representation might be a potential countermeasure to the usage of relatively bad advice. However, the effect of this antidote weakens when forecast intervals become less informative.

Artificial Intelligence, in particular the novel possibilities supplied by GPT-4, is increasingly being utilized in educational settings, yet its impact on student activation and learning outcomes remains controversial. We conduct a lab-in-the-field experiment in undergraduate tutorial classes in macroeconomics at the university level. Over the course of one semester, we asked students to answer eight open-ended questions. Depending on the treatment, students received lecturer feedback at the classroom level only (LF), additional individual feedback from their peers (PF), or from the AI (AIF). We find that AIF has a significant positive effect on student activation. Compared to LF, continuous participation in the tasks is significantly higher in AIF, and it induces the longest written answers across the eight tasks. In terms of learning outcomes, AIF stands out for producing the most significant improvement in content. For the style of answers, we find no effects. We attribute the larger effects of AIF compared to PF to the higher reliability and quality of feedback provision of the AI. Our findings demonstrate that AI, specifically GPT-4, can offer a scalable and consistent solution for providing individual feedback in educational settings.

Deferred compensation is often proposed as an instrument to prevent managerial myopia. However, empirical studies show that its practical use is limited when it comes to managerial retirement. We study the optimal design of accounting‐based deferred compensation for retiring managers. While deferred compensation is useful in establishing long‐term incentives, it causes contracting frictions in subsequent periods. Deferred bonuses of retiring managers imply inefficiently weak incentives for incoming managers. This down‐scaling effect renders deferred compensation less useful in providing long‐term incentives. We also find that the down‐scaling effect has implications for the desirability of accounting timeliness—that is, the timely recognition of future cash flows in current accounting earnings—from a stewardship perspective. If managers' long‐term actions are sufficiently important, higher timeliness can cause more myopic managerial incentives.

Estimation of distribution algorithms (EDAs) are general-purpose optimizers that maintain a probability distribution over a given search space. This probability distribution is updated through sampling from the distribution and a reinforcement learning process which rewards solution components that have shown to be part of good quality samples. The compact genetic algorithm (cGA) is a non-elitist EDA able to deal with difficult multimodal fitness landscapes that are hard to solve by elitist algorithms. We investigate the cGA on the Cliff function for which it was shown recently that non-elitist evolutionary algorithms and artificial immune systems optimize it in expected polynomial time. We point out that the cGA faces major difficulties when solving the Cliff function and investigate its dynamics both experimentally and theoretically. Our experimental results indicate that the cGA requires exponential time for all values of the update strength 1/K. We show theoretically that, under sensible assumptions, there is a negative drift when sampling around the location of the cliff. Experiments further suggest that there is a phase transition for K where the expected optimization time drops from $n^{\Theta (n)}$ to $2^{\Theta (n)}$.

Previous research on political communication on Russia's most popular social network VK has concluded that most users avoid news by not following legacy-news accounts. In this study, we expand the universe of scrutinized accounts with the most-followed non-legacy-news accounts (>100,000 followers) that regularly publish what we theorize to be ‘explicitly political content’ (EPC; N = 355). We delineate a typology of six types of EPC accounts, calculate their aggregate follower counts, and determine how many of them were still (1) accessible from Russia and (2) publishing Kremlin-critical content in October 2022. Our findings indicate that non-critical accounts attracted 26 times more followers than Kremlin-critical accounts. Entertainment-focused EPC accounts had seven times more followers than legacy-news accounts. As a result, they became the primary means through which non-critical EPC reached news-avoidant mass audiences. We identify three dimensions through which autocrats can interweave propaganda and entertainment and highlight promising research paths.

The essay briefly draws in references from Nilima Ibrahim’s Ami Virangana Bolchhi (1996) (along with various other literature on Biranganas) and Yuki Tanaka’s Hidden Horrors: Japanese War Crimes in World War II (2017) and other testimonies, to highlight the politics behind homogenizing women who were victims of genocidal rape during war, as “brave” in an attempt to systemically overlook the atrocities that went on. Violence is a pervasive factor of the human experience.

Expressions in which the word for a body part is also used for objects can be found in many languages. Some languages use body part terms to refer to object parts, while others have only a few idiosyncratic examples in their vocabulary. Studying the word forms referring to body and object concepts, i.e., colexifications, across languages, offers insights into cognitive principles facilitating such usage. Previous studies focused on full colexifications in which the same word form expresses two distinct concepts. Here, we utilize a new approach that allows us to analyze partial colexifications in which a concept is built out of the word forms for two separate concepts, like river mouth. Based on a large lexical database, we identified body and object concepts and analyzed 39 colexifications across 329 languages. The results show that word forms for body concepts are used slightly more frequently as a source for object names. However, the detailed examination of directional tendencies and colexifications of word forms between body and object concepts reveals linguistic variation. The study sheds light on meaning extensions between two concrete domains and showcases the synergies that arise through the combination of existing data and methods.

Studies regularly demonstrate how well intelligent agents (IAs) can support humans or are demonstrably superior to them in some areas. Given that some tasks likely remain unsuitable for even the most intelligent machines in the mid-future, work in hybrid teams of humans and IAs—where the capabilities of both are effectively combined—will most likely shape the way we work in the coming decades. In an abductive study, we investigate an early example of hybrid teams, consisting of a conversational intelligent agent (IA) and humans, that aims to improve health behavior or change personality traits. We theorize Transactive Intelligent Memory System (TIMS) as a new vision of collaboration between humans and IAs in hybrid teams, based on our empirical insights and our literature review on transactive memory systems theory. Our empirical evidence shows that IAs can develop a form of individual and external memory, and hybrid teams of humans and IAs can realize joint systems of transactive memory—a competence that current literature only ascribes to humans. We further find that whether individuals view IAs merely as external memory aids or as part of their teams’ transactive memory is moderated by the tasks’ complexity and knowledge intensity, as well as the IA’s ability to complete the task. This theorizing helps to better understand the role of IAs in future team-based working processes. Developers of IAs can use TIMS as a tool for requirements formulation to prepare their software agents for collaboration in hybrid teams.

Critical infrastructures, such as the electric grid, water supply systems or transportation systems, empower our modern society. Their disruption can seriously impair the daily lives of millions of people and jeopardize the economy. Due to this fact, they are attractive targets in a cyber war or in large-scale sophisticated attacks. Moreover, in disasters or crises, critical infrastructures might face severe perturbations or even a breakdown, thus affecting the population at large. This chapter begins by introducing the concept of resiliency in critical infrastructures: resilient infrastructures are designed to withstand disasters, crises, and negative influence. They can maintain their core functionalities even under attack. The chapter subsequently discusses how critical infrastructures can be made resilient. This requires adopting a defence in depth concept, i.e. deploying multiple layers of security controls, but we also provide further recommendations to this end.