Search Results for author: Panagiotis Karras

Found 16 papers, 8 papers with code

Autonomous microARPES

no code implementations16 Feb 2024 Steinn Ymir Agustsson, Alfred J. H. Jones, Davide Curcio, Søren Ulstrup, Jill Miwa, Davide Mottin, Panagiotis Karras, Philip Hofmann

Angle-resolved photoemission spectroscopy (ARPES) is a technique used to map the occupied electronic structure of solids.

EUGENE: Explainable Unsupervised Approximation of Graph Edit Distance

no code implementations8 Feb 2024 Aditya Bommakanti, Harshith Reddy Vonteri, Sayan Ranu, Panagiotis Karras

The need to identify graphs having small structural distance from a query arises in biology, chemistry, recommender systems, and social network analysis.

Recommendation Systems

MCWDST: a Minimum-Cost Weighted Directed Spanning Tree Algorithm for Real-Time Fake News Mitigation in Social Media

1 code implementation23 Feb 2023 Ciprian-Octavian Truică, Elena-Simona Apostol, Radu-Cătălin Nicolescu, Panagiotis Karras

The widespread availability of internet access and handheld devices confers to social media a power similar to the one newspapers used to have.

DANES: Deep Neural Network Ensemble Architecture for Social and Textual Context-aware Fake News Detection

1 code implementation1 Feb 2023 Ciprian-Octavian Truică, Elena-Simona Apostol, Panagiotis Karras

The growing popularity of social media platforms has simplified the creation and distribution of news articles but also creates a conduit for spreading fake news.

Fake News Detection Network Embedding

Maximizing the Probability of Fixation in the Positional Voter Model

no code implementations26 Nov 2022 Petros Petsinis, Andreas Pavlogiannis, Panagiotis Karras

The Voter model is a well-studied stochastic process that models the invasion of a novel trait $A$ (e. g., a new opinion, social meme, genetic mutation, magnetic spin) in a network of individuals (agents, people, genes, particles) carrying an existing resident trait $B$.

Invasion Dynamics in the Biased Voter Process

no code implementations20 Jan 2022 Loke Durocher, Panagiotis Karras, Andreas Pavlogiannis, Josef Tkadlec

We show that the problem is NP-hard for both $r>1$ and $r<1$, while the latter case is also inapproximable within any multiplicative factor.

Atrapos: Real-time Evaluation of Metapath Query Workloads

1 code implementation11 Jan 2022 Serafeim Chatzopoulos, Thanasis Vergoulis, Dimitrios Skoutas, Theodore Dalamagas, Christos Tryfonopoulos, Panagiotis Karras

In this paper, we present ATRAPOS, a new approach for the real-time evaluation of metapath query workloads that leverages a combination of efficient sparse matrix multiplication and intermediate result caching.

GRASP: Graph Alignment through Spectral Signatures

no code implementations10 Jun 2021 Judith Hermanns, Anton Tsitsulin, Marina Munkhoeva, Alex Bronstein, Davide Mottin, Panagiotis Karras

In this paper, we transfer the shape-analysis concept of functional maps from the continuous to the discrete case, and treat the graph alignment problem as a special case of the problem of finding a mapping between functions on graphs.

FREDE: Anytime Graph Embeddings

no code implementations8 Jun 2020 Anton Tsitsulin, Marina Munkhoeva, Davide Mottin, Panagiotis Karras, Ivan Oseledets, Emmanuel Müller

Low-dimensional representations, or embeddings, of a graph's nodes facilitate several practical data science and data engineering tasks.

Graph Embedding

Equitable Stable Matchings in Quadratic Time

1 code implementation NeurIPS 2019 Nikolaos Tziavelis, Ioannis Giannakopoulos, Katerina Doka, Nectarios Koziris, Panagiotis Karras

Can a stable matching that achieves high equity among the two sides of a market be reached in quadratic time?

The Shape of Data: Intrinsic Distance for Data Distributions

2 code implementations ICLR 2020 Anton Tsitsulin, Marina Munkhoeva, Davide Mottin, Panagiotis Karras, Alex Bronstein, Ivan Oseledets, Emmanuel Müller

The ability to represent and compare machine learning models is crucial in order to quantify subtle model changes, evaluate generative models, and gather insights on neural network architectures.

SGR: Self-Supervised Spectral Graph Representation Learning

no code implementations15 Nov 2018 Anton Tsitsulin, Davide Mottin, Panagiotis Karras, Alex Bronstein, Emmanuel Müller

Representing a graph as a vector is a challenging task; ideally, the representation should be easily computable and conducive to efficient comparisons among graphs, tailored to the particular data and analytical task at hand.

Graph Representation Learning

NetLSD: Hearing the Shape of a Graph

1 code implementation27 May 2018 Anton Tsitsulin, Davide Mottin, Panagiotis Karras, Alex Bronstein, Emmanuel Müller

However, it is a hard task in terms of the expressiveness of the employed similarity measure and the efficiency of its computation.

Social and Information Networks

VERSE: Versatile Graph Embeddings from Similarity Measures

2 code implementations13 Mar 2018 Anton Tsitsulin, Davide Mottin, Panagiotis Karras, Emmanuel Müller

Embedding a web-scale information network into a low-dimensional vector space facilitates tasks such as link prediction, classification, and visualization.

Link Prediction

Stochastic Database Cracking: Towards Robust Adaptive Indexing in Main-Memory Column-Stores

1 code implementation1 Feb 2012 Felix Halim, Stratos Idreos, Panagiotis Karras, Roland H. C. Yap

Stochastic cracking also uses each query as a hint on how to reorganize data, but not blindly so; it gains resilience and avoids performance bottlenecks by deliberately applying certain arbitrary choices in its decision-making.

Decision Making

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