Search Results for author: Denis Helic

Found 8 papers, 4 papers with code

Structack: Structure-based Adversarial Attacks on Graph Neural Networks

1 code implementation23 Jul 2021 Hussain Hussain, Tomislav Duricic, Elisabeth Lex, Denis Helic, Markus Strohmaier, Roman Kern

In this work, we study adversarial attacks that are uninformed, where an attacker only has access to the graph structure, but no information about node attributes.

RFID-based Article-to-Fixture Predictions in Real-World Fashion Stores

no code implementations21 May 2021 Matthias Wölbitsch, Thomas Hasler, Patrick Kasper, Denis Helic, Simon Walk

Additionally, we conduct a pilot to investigate the challenges related to the integration of such a localization system in the day-to-day business of retail stores.

Time Series

Surfacing Estimation Uncertainty in the Decay Parameters of Hawkes Processes with Exponential Kernels

no code implementations2 Apr 2021 Tiago Santos, Florian Lemmerich, Denis Helic

With a series of experiments with synthetic and real-world data from domains such as "classical" earthquake modeling or the manifestation of collective emotions on Twitter, we demonstrate that our proposed approach helps to quantify uncertainty and thereby to understand and fit Hawkes processes in practice.

Time Series

Volunteer contributions to Wikipedia increased during COVID-19 mobility restrictions

1 code implementation19 Feb 2021 Thorsten Ruprechter, Manoel Horta Ribeiro, Tiago Santos, Florian Lemmerich, Markus Strohmaier, Robert West, Denis Helic

Wikipedia, the largest encyclopedia ever created, is a global initiative driven by volunteer contributions.

Computers and Society

Synwalk -- Community Detection via Random Walk Modelling

2 code implementations21 Jan 2021 Christian Toth, Denis Helic, Bernhard C. Geiger

We thoroughly validate the effectiveness of our approach on synthetic and empirical networks, respectively, and compare Synwalk's performance with the performance of Infomap and Walktrap.

Community Detection

On the Impact of Communities on Semi-supervised Classification Using Graph Neural Networks

1 code implementation30 Oct 2020 Hussain Hussain, Tomislav Duricic, Elisabeth Lex, Roman Kern, Denis Helic

In this work, we systematically study the impact of community structure on the performance of GNNs in semi-supervised node classification on graphs.

General Classification Model Selection +1

Empirical Comparison of Graph Embeddings for Trust-Based Collaborative Filtering

no code implementations30 Mar 2020 Tomislav Duricic, Hussain Hussain, Emanuel Lacic, Dominik Kowald, Denis Helic, Elisabeth Lex

In this work, we study the utility of graph embeddings to generate latent user representations for trust-based collaborative filtering.

Collaborative Filtering Network Embedding

How Users Explore Ontologies on the Web: A Study of NCBO's BioPortal Usage Logs

no code implementations28 Oct 2016 Simon Walk, Lisette Espín-Noboa, Denis Helic, Markus Strohmaier, Mark Musen

In particular, we were able to identify seven distinct browsing-behavior types, which all make use of different functionality provided by BioPortal.

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