arXiv subjects

Alexander Nolte

Publications and source records attributed to Alexander Nolte.

At least 19 recordsLinked to original sources

arXiv2026

Quick Build, Careful Check? Generative AI Use in Hackathons

Hackathons are time-bounded events where participants form teams to rapidly build software projects. Their short-term nature makes them a natural setting for Generative AI (GenAI) use, given its promise of speed and efficiency. Yet despite GenAI being increasingly adopted in these events, we still know little about what participants use GenAI for and, crucially, what they do not use it for and why. We report an exploratory interview study with participants from different teams at a two-day AI-themed hackathon in central Europe. We found that participants used GenAI for purposes beyond coding, including learning unfamiliar topics, brainstorming, and preparing documentation. At the same time, they combined multiple GenAI and non-GenAI tools depending on task fit. We also found that, despite the absence of team rules, all participants we studied converged on an unwritten practice of checking GenAI output before using it, yet their ability to actually verify was constrained by time pressure and limited domain knowledge. This work aims to identify avenues for further investigation by outlining a follow-up study combining observation, surveys, and prompt-and-response logs.

cs.SE↗

arXiv2026

HackRep: A Large-Scale Dataset of GitHub Hackathon Projects

Hackathons are time-bound collaborative events that often target software creation. Although hackathons have been studied in the past, existing work focused on in-depth case studies limiting our understanding of hackathons as a software engineering activity. To complement the existing body of knowledge, we introduce HackRep, a dataset of 100,356 hackathon GitHub repositories. We illustrate the ways HackRep can benefit software engineering researchers by presenting a preliminary investigation of hackathon project continuation, hackathon team composition, and an estimation of hackathon geography. We further display the opportunities of using this dataset, for instance showing the possibility of estimating hackathon durations based on commit timestamps.

cs.SE↗

arXiv2026

Homotopy types of fine curve and fine arc complexes

The fine curve complex of a surface is a simplicial complex whose vertices are essential simple closed curves and whose $k$-simplices are collections of $k+1$ disjoint curves. We prove that the fine curve complex is homotopy equivalent to the curve complex. We also prove that the fine arc complex is contractible.

math.GT↗

arXiv2026

Graphs of Quasicircles and Quasiconformal Homeomorphisms

We give a combinatorial characterization of the group of quasiconformal homeomorphisms of a closed, oriented surface $S$ of genus at least $2$. In particular, we prove they are exactly the automorphisms of a graph of essential quasicircles on $S$ that respect a canonical coarse ordering induced by quality constants. We also discuss the coarse geometry of this graph.

math.GT↗

arXiv2025

Flexibility and degeneracy around a theorem of Thurston

We give two flexible and degenerate constructions related to a theorem of Thurston. First, we produce geodesic segments for Thurston's asymmetric metric on Teichm\"uller space $\mathcal{T}(S_g)$ that remain geodesics after adding arbitrary $\varepsilon$-Lipschitz noise to all but one Fenchel-Nielsen coordinate. Then, for all $2 < n \leq 3g-3$ we construct open sets in $\mathcal{T}(S_g)^n$ for which the limit cones of the corresponding representations in $\mathrm{PSL}_2(\mathbb{R})^n$ are cones over explicit finite-sided polyhedra. Each construction is as degenerate as possible and has applications to the basic structure and local non-rigidity of the involved objects.

math.GT↗

arXiv2025

"Can you feel the vibes?": An exploration of novice programmer engagement with vibe coding

Emerging alongside generative AI and the broader trend of AI-assisted coding, the term "vibe coding" refers to creating software via natural language prompts rather than direct code authorship. This approach promises to democratize software development, but its educational implications remain underexplored. This paper reports on a one-day educational hackathon investigating how novice programmers and mixed-experience teams engage with vibe coding. We organized an inclusive event at a Brazilian public university with 31 undergraduate participants from computing and non-computing disciplines, divided into nine teams. Through observations, an exit survey, and semi-structured interviews, we examined creative processes, tool usage patterns, collaboration dynamics, and learning outcomes. Findings reveal that vibe coding enabled rapid prototyping and cross-disciplinary collaboration, with participants developing prompt engineering skills and delivering functional demonstrations within time constraints. However, we observed premature convergence in ideation, uneven code quality requiring rework, and limited engagement with core software engineering practices. Teams adopted sophisticated workflows combining multiple AI tools in pipeline configurations, with human judgment remaining essential for critical refinement. The short format (9 hours) proved effective for confidence-building among newcomers while accommodating participants with limited availability. We conclude that vibe coding hackathons can serve as valuable low-stakes learning environments when coupled with explicit scaffolds for divergent thinking, critical evaluation of AI outputs, and realistic expectations about production quality.

cs.SE↗

arXiv2025

In-person, Online and Back Again -- A Tale of Three Hybrid Hackathons

Hybrid hackathons, which combine in-person and online participation, present unique challenges for organizers and participants. Although such events are increasingly conducted, research on them remains fragmented, with limited integration between hackathon studies and hybrid collaboration. Existing strategies for in-person or online-only events often fail to address the unique challenges of hybrid formats, such as managing communication across physical and virtual spaces. Our work addresses this gap by examining how hybrid hackathons function, analyzing how organizers structure these events and how participants navigate hybrid-specific challenges. Drawing on established theories of hybrid collaboration, we examine key dimensions - synchronicity, physical distribution, dynamic transitions, and technological infrastructure - that shape collaboration in hybrid events. Through an exploratory case study of three hackathon events, we analyze how these dimensions are implemented and their effects on participant experiences. Our findings reveal differing organizer considerations of the hybrid dimensions in the hackathon design, leading to distinct experiences for participants. Implementation styles - favoring in-person, online, or balanced participation - led to varied participant experiences, affecting access to resources, communication, and team coordination. Organizers in our study also relied on technology to bridge hybrid interactions, but overlooked critical aspects like time-zone management, dynamic transitions, and targeted support for hybrid teams. Additionally, participants in their teams responded to gaps in event scaffolding by adapting collaboration strategies, revealing gaps in organizers' preparedness for hybrid events. Learning from our findings, we offer practical recommendations when organizing hybrid hackathon events and recommendations to participants when attending them.

cs.HC↗

arXiv2025

How Do Hackathons Foster Creativity? Towards AI Collaborative Evaluation of Creativity at Scale

Hackathons have become popular collaborative events for accelerating the development of creative ideas and prototypes. There are several case studies showcasing creative outcomes across domains such as industry, education, and research. However, there are no large-scale studies on creativity in hackathons which can advance theory on how hackathon formats lead to creative outcomes. We conducted a computational analysis of 193,353 hackathon projects. By operationalizing creativity through usefulness and novelty, we refined our dataset to 10,363 projects, allowing us to analyze how participant characteristics, collaboration patterns, and hackathon setups influence the development of creative projects. The contribution of our paper is twofold: We identified means for organizers to foster creativity in hackathons. We also explore the use of large language models (LLMs) to augment the evaluation of creative outcomes and discuss challenges and opportunities of doing this, which has implications for creativity research at large.

cs.HC↗

arXiv2024

Computational Diplomacy: How "hackathons for good" feed a participatory future for multilateralism in the digital age

This article explores the role of hackathons for good in building a community of software and hardware developers focused on addressing global SDG challenges. We theorise this movement as computational diplomacy: a decentralised, participatory process for digital governance that leverages collective intelligence to tackle major global issues. Analysing Devpost and GitHub data reveals that 30% of hackathons since 2010 have addressed SDG topics, employing diverse technologies to create innovative solutions. Hackathons serve as crucial kairos moments, sparking innovation bursts that drive both immediate project outcomes and long-term production. We propose that these events harness the neurobiological basis of human cooperation and empathy, fostering a collective sense of purpose and reducing interpersonal prejudice. This bottom-up approach to digital governance integrates software development, human collective intelligence, and collective action, creating a dynamic model for transformative change. By leveraging kairos moments, computational diplomacy promotes a more inclusive and effective model for digital multilateral governance of the future.

cs.CY↗

arXiv2024

Concave Foliated Flag Structures and the $\text{SL}_3(\mathbb{R})$ Hitchin Component

We give a geometric characterization of flag geometries associated to Hitchin representations in $\text{SL}_3(\mathbb{R})$. Our characterization is based on distinguished invariant foliations, similar to those studied by Guichard-Wienhard in $\text{PSL}_4(\mathbb{R})$. We connect to the dynamics of Hitchin representations by constructing refraction flows for all positive roots in general $\mathfrak{sl}_n(\mathbb{R})$ in our setting. For $n = 3$, leaves of our one-dimensional foliations are flow-lines. One consequence is that the highest root flows are $C^{1+\alpha}$.

math.GT↗

arXiv2024

On Foliations in $\text{PSL}(4,\mathbb{R})$-Teichm\"uller Theory

We carry out a detailed study of the structure of domains of discontinuity $\Omega_\rho$ in $\mathbb{RP}^3$ of $\text{PSL}_4(\mathbb{R})$-Hitchin representations $\rho$. We then prove the foliated component $\Omega_\rho^1$ of $\Omega_\rho$ has exactly two group-invariant foliations by properly embedded projective line segments and has a unique foliation by properly embedded convex domains in projective planes. This gives a finiteness counterpart to work of Guichard and Wienhard. We also prove analogues for the non-foliated component $\Omega_\rho^2$ and deduce a rigidity of projective equivalences of properly convex foliated projective structures on unit tangent bundles of surfaces.

math.GT↗

arXiv2024

Metrics on Hitchin Components from H\"older Distortion

We observe Thurston's asymmetric metric on Teichm\"uller space may be expressed in terms of the H\"older regularity of boundary maps. We then associate $2$-dimensional stratified loci in $\mathbb{RP}^{n-1}$ to $\text{PSL}_n(\mathbb{R})$ Hitchin representations with $n > 3$. We prove that measuring the relative H\"older distortion of these loci gives asymmetric metrics on the Hitchin component $\text{Hit}_n(S)$ with complete and geometrically meaningful symmetrizations. These are the first known geometrically significant complete metrics on $\text{Hit}_n(S)$ for $n > 3$.

math.GT↗

arXiv2023

Leaves of Foliated Projective Structures

The $\text{PSL}(4,\mathbb{R})$ Hitchin component of a closed surface group $π_1(S)$ consists of holonomies of properly convex foliated projective structures on the unit tangent bundle of $S$. We prove that the leaves of the codimension-$1$ foliation of any such projective structure are all projectively equivalent if and only if its holonomy is Fuchsian. This implies constraints on the symmetries and shapes of these leaves. We also give an application to the topology of the non-${\rm T}_0$ space $\mathfrak{C}(\mathbb{RP}^n)$ of projective classes of properly convex domains in $\mathbb{RP}^n$. Namely, Benzécri asked in 1960 if every closed subset of $\mathfrak{C}(\mathbb{RP}^n)$ that contains no proper nonempty closed subset is a point. Our results imply a negative resolution for $n \geq 2$.

math.GT↗

arXiv2023

An Exploratory Study on the Evidence of Hackathons' Role in Solving OSS Newcomers' Challenges

Background: OSS projects face various challenges. One major challenge is to onboard and integrate newcomers to the project. Aim: We aim to understand and discuss the challenges newcomers face when joining an OSS project and present evidence on how hackathons can mitigate those challenges. Method: We conducted two searches on digital libraries to (1) explore challenges faced by newcomers to join OSS projects, and (2) collect evidence on how hackathons were used to address them. We defined four evidence categories (positive, inconclusive, and no evidence) to classify evidence how hackathons address challenges. In addition, we investigated whether a hackathon event was related to an OSS project or not. Result: We identified a range of newcomer challenges that were successfully addressed using hackathons. However, not all of the solutions we identified were applied in the context of OSS. Conclusion: There seems to be potential in using hackathons to overcome newcomers' challenges in OSS projects and allow them to integrate faster into the project.

cs.SE↗

arXiv2023

Characterizing candidates for Cannon's Conjecture from Geometric Measure Theory

We show that recent work of Song implies that torsion-free hyperbolic groups with Gromov boundary $S^2$ are realized as fundamental groups of closed 3-manifolds of constant negative curvature if and only if the solution to an associated spherical Plateau problem for group homology is isometric to such a 3-manifold, and suggest some related questions.

math.GT↗

arXiv2022

The Future of Hackathon Research and Practice

Hackathons are time-bounded collaborative events which have become a global phenomenon adopted by both researchers and practitioners in a plethora of contexts. Hackathon events are generally used to accelerate the development of, for example, scientific results and collaborations, communities, and innovative prototypes addressing urgent challenges. As hackathons have been adopted into many different contexts, the events have also been adapted in numerous ways corresponding to the unique needs and situations of organizers, participants and other stakeholders. While these interdisciplinary adaptions, in general affords many advantages - such as tailoring the format to specific needs - they also entail certain challenges, specifically: 1) limited exchange of best practices, 2) limited exchange of research findings, and 3) larger overarching questions that require interdisciplinary collaboration are not discovered and remain unaddressed. We call for interdisciplinary collaborations to address these challenges. As a first initiative towards this, we performed an interdisciplinary collaborative analysis in the context of a workshop at the Lorentz Center, Leiden in December 2021. In this paper, we present the results of this analysis in terms of six important areas which we envision to contribute to maturing hackathon research and practice: 1) hackathons for different purposes, 2) socio-technical event design, 3) scaling up, 4) making hackathons equitable, 5) studying hackathons, and 6) hackathon goals and how to reach them. We present these areas in terms of the state of the art and research proposals and conclude the paper by suggesting next steps needed for advancing hackathon research and practice.

cs.HC↗

arXiv2022

One-off Events? An Empirical Study of Hackathon Code Creation and Reuse

Background: Hackathons have become popular events for teams to collaborate on projects and develop software prototypes. Most existing research focuses on activities during an event with limited attention to the evolution of the hackathon code. Aim: We aim to understand the evolution of code used in and created during hackathon events, with a particular focus on the code blobs, specifically, how frequently hackathon teams reuse pre-existing code, how much new code they develop, if that code gets reused afterward, and what factors affect reuse. Method: We collected information about 22,183 hackathon projects from DevPost and obtained related code blobs, authors, project characteristics, original author, code creation time, language, and size information from World of Code. We tracked the reuse of code blobs by identifying all commits containing blobs created during hackathons and identifying all projects that contain those commits. We also conducted a series of surveys in order to gain a deeper understanding of hackathon code evolution that we sent out to hackathon participants whose code was reused, whose code was not reused, and developers who reused some hackathon code. Result: 9.14% of the code blobs in hackathon repositories and 8% of the lines of code (LOC) are created during hackathons and around a third of the hackathon code gets reused in other projects by both blob count and LOC. The number of associated technologies and the number of participants in hackathons increase the reuse probability. Conclusion: The results of our study demonstrate hackathons are not always "one-off" events as common knowledge dictates and they can serve as a starting point for further studies in this area.

cs.SE↗

arXiv2022

Socio-technical constraints and affordances of virtual collaboration -- A study of four online hackathons

Hackathons and similar time-bounded events have become a popular form of collaboration. They are commonly organized as in-person events during which teams engage in intense collaboration over a short period of time to complete a project that is of interest to them. Most research to date has focused on studying how teams collaborate in a co-located setting, pointing towards the advantages of radical co-location. The global pandemic of 2020, however, has led to many hackathons moving online, which challenges our current understanding of how they function. In this paper, we address this gap by presenting findings from a multiple-case study of 10 hackathon teams that participated in 4 hackathons across two continents. By analyzing the collected data, we found that teams merged synchronous and asynchronous means of communication to maintain a common understanding of work progress as well as to maintain awareness of each other's tasks. Task division was self-assigned based on individual skills or interests, while leaders emerged from different strategies (e.g., participant experience, the responsibility of registering the team in an event). Some of the affordances of in-person hackathons, such as the radical co-location of team members, could be partially reproduced in teams that kept synchronous communication channels while working (i.e., shared audio territories), in a sort of "radical virtual co-location". However, others, such as interactions with other teams, easy access to mentors, and networking with other participants, decreased. In addition, the technical constraints of the different communication tools and platforms brought technical problems and were overwhelming to participants. Our work contributes to understanding the virtual collaboration of small teams in the context of online hackathons and how technologies and event structures proposed by organizers imply this collaboration.

cs.HC↗