Stable Roommate Problem with Diversity Preferences

In the multidimensional stable roommate problem, agents have to be allocated to rooms and have preferences over sets of potential roommates. We study the complexity of finding good allocations of agents to rooms under the assumption that agents have diversity preferences [Bredereck et al., 2019]: each agent belongs to one of the two types (e.g., juniors and seniors, artists and engineers), and agents' preferences over rooms depend solely on the fraction of agents of their own type among their potential roommates. We consider various solution concepts for this setting, such as core and exchange stability, Pareto optimality and envy-freeness. On the negative side, we prove that envy-free, core stable or (strongly) exchange stable outcomes may fail to exist and that the associated decision problems are NP-complete. On the positive side, we show that these problems are in FPT with respect to the room size, which is not the case for the general stable roommate problem. Moreover, for the classic setting with rooms of size two, we present a linear-time algorithm that computes an outcome that is core and exchange stable as well as Pareto optimal. Many of our results for the stable roommate problem extend to the stable marriage problem.Comment: accepted to IJCAI'2

Stable Marriage with Multi-Modal Preferences

We introduce a generalized version of the famous Stable Marriage problem, now based on multi-modal preference lists. The central twist herein is to allow each agent to rank its potentially matching counterparts based on more than one "evaluation mode" (e.g., more than one criterion); thus, each agent is equipped with multiple preference lists, each ranking the counterparts in a possibly different way. We introduce and study three natural concepts of stability, investigate their mutual relations and focus on computational complexity aspects with respect to computing stable matchings in these new scenarios. Mostly encountering computational hardness (NP-hardness), we can also spot few islands of tractability and make a surprising connection to the \textsc{Graph Isomorphism} problem

Parameterized Complexity of Stable Roommates with Ties and Incomplete Lists Through the Lens of Graph Parameters

We continue and extend previous work on the parameterized complexity analysis of the NP-hard Stable Roommates with Ties and Incomplete Lists problem, thereby strengthening earlier results both on the side of parameterized hardness as well as on the side of fixed-parameter tractability. Other than for its famous sister problem Stable Marriage which focuses on a bipartite scenario, Stable Roommates with Incomplete Lists allows for arbitrary acceptability graphs whose edges specify the possible matchings of each two agents (agents are represented by graph vertices). Herein, incomplete lists and ties reflect the fact that in realistic application scenarios the agents cannot bring all other agents into a linear order. Among our main contributions is to show that it is W[1]-hard to compute a maximum-cardinality stable matching for acceptability graphs of bounded treedepth, bounded tree-cut width, and bounded feedback vertex number (these are each time the respective parameters). However, if we "only" ask for perfect stable matchings or the mere existence of a stable matching, then we obtain fixed-parameter tractability with respect to tree-cut width but not with respect to treedepth. On the positive side, we also provide fixed-parameter tractability results for the parameter feedback edge set number

New Applications of the Nearest-Neighbor Chain Algorithm

The nearest-neighbor chain algorithm was proposed in the eighties as a way to speed up certain hierarchical clustering algorithms. In the first part of the dissertation, we show that its application is not limited to clustering. We apply it to a variety of geometric and combinatorial problems. In each case, we show that the nearest-neighbor chain algorithm finds the same solution as a preexistent greedy algorithm, but often with an improved runtime. We obtain speedups over greedy algorithms for Euclidean TSP, Steiner TSP in planar graphs, straight skeletons, a geometric coverage problem, and three stable matching models. In the second part, we study the stable-matching Voronoi diagram, a type of plane partition which combines properties of stable matchings and Voronoi diagrams. We propose political redistricting as an application. We also show that it is impossible to compute this diagram in an algebraic model of computation, and give three algorithmic approaches to overcome this obstacle. One of them is based on the nearest-neighbor chain algorithm, linking the two parts together

Reading men's lifestyle magazines in contemporary China

Men's lifestyle magazines came to China at the turn of the 21st century, as a result of commercialization and the globalization of the media. They have prospered in the last decade along with the marked emergence of a new "middle class" in China and their pursuit and imagination of a consumerist lifestyle. Reflecting dynamic negotiation and hybridization between global and local discourses, the men's lifestyle magazine, as a form of popular culture, points to new possibilities of gender and sexuality in post-socialist China. In particular, targeting the newly-emerged social elite, these magazines construct and promote a new mode of masculinity that is characterized by hedonism, consumerism, and cosmopolitanism. The thesis aims at developing a framework for understanding men's lifestyle magazines in China by focusing on this new mode of manhood, which, as an aspirational model, represents a new development of Chinese masculinities that are significantly different from both the Confucian and Maoist discourses. At the centre of the discourse of consumerist masculinity is the pursuit of a lifestyle defined by pinwei or "good taste", which is rendered modern and Westernized by readers and is closely associated with a middle-class identity and fantasy. As an interdisciplinary study of men's magazines in China, the thesis synthesizes research methods of both media studies and gender studies. From the perspective of media studies, it investigates the ownership patterns of the magazines, i.e., local copyright ownership versus shared copyright ownership with established overseas magazines. Comparison has been made between the two types of magazines in terms of representations of lifestyle, masculinity and consumerism. Based on interviews and surveys with magazine editors and readers, the study empirically examines the production, reception and interpretation of these magazines and the male images constructed and promoted by them. By content analysis and critical readings of the verbal and visual texts, the study also compares Chinese editions of international titles such as FHM and Esquire with their "mother editions" in the West and probes into the localization of Western hegemonic masculinity in China. In addition, the distinctive "Chinese characteristics" of the magazines, namely elitism and nationalism, have been embedded in the social and ideological context of post-socialist China. In light of gender studies theory, the study interprets different types of spectatorship of the body in the magazines and examines the cultural habitus of the new "middle class" as desiring subjects