Search Results for author: Charalampos E. Tsourakakis

Found 12 papers, 9 papers with code

Markovletics: Methods and A Novel Application for Learning Continuous-Time Markov Chain Mixtures

no code implementations27 Feb 2024 Fabian Spaeh, Charalampos E. Tsourakakis

A notable unresolved query in stochastic processes is learning mixtures of continuous-time Markov chains (CTMCs).

Learning Mixtures of Markov Chains with Quality Guarantees

1 code implementation9 Feb 2023 Fabian Spaeh, Charalampos E. Tsourakakis

Finally, we empirically observe that combining an EM-algorithm with our method performs best in practice, both in terms of reconstruction error with respect to the distribution of 3-trails and the mixture of Markov Chains.

On the Power of Edge Independent Graph Models

1 code implementation NeurIPS 2021 Sudhanshu Chanpuriya, Cameron Musco, Konstantinos Sotiropoulos, Charalampos E. Tsourakakis

We prove that subject to a bounded overlap condition, which ensures that the model does not simply memorize a single graph, edge independent models are inherently limited in their ability to generate graphs with high triangle and other subgraph densities.

DeepWalking Backwards: From Embeddings Back to Graphs

1 code implementation17 Feb 2021 Sudhanshu Chanpuriya, Cameron Musco, Konstantinos Sotiropoulos, Charalampos E. Tsourakakis

Our findings are a step towards a more rigorous understanding of exactly what information embeddings encode about the input graph, and why this information is useful for learning tasks.

Node Embeddings and Exact Low-Rank Representations of Complex Networks

1 code implementation NeurIPS 2020 Sudhanshu Chanpuriya, Cameron Musco, Konstantinos Sotiropoulos, Charalampos E. Tsourakakis

In this work we show that the results of Seshadhri et al. are intimately connected to the model they use rather than the low-dimensional structure of complex networks.

Clustering

Optimal Learning of Joint Alignments with a Faulty Oracle

no code implementations21 Sep 2019 Kasper Green Larsen, Michael Mitzenmacher, Charalampos E. Tsourakakis

The goal is to recover $n$ discrete variables $g_i \in \{0, \ldots, k-1\}$ (up to some global offset) given noisy observations of a set of their pairwise differences $\{(g_i - g_j) \bmod k\}$; specifically, with probability $\frac{1}{k}+\delta$ for some $\delta > 0$ one obtains the correct answer, and with the remaining probability one obtains a uniformly random incorrect answer.

TwitterMancer: Predicting Interactions on Twitter Accurately

no code implementations25 Apr 2019 Konstantinos Sotiropoulos, John W. Byers, Polyvios Pratikakis, Charalampos E. Tsourakakis

This paper investigates the interplay between different types of user interactions on Twitter, with respect to predicting missing or unseen interactions.

Graph Mining

Opinion Dynamics with Varying Susceptibility to Persuasion

1 code implementation24 Jan 2018 Rediet Abebe, Jon Kleinberg, David Parkes, Charalampos E. Tsourakakis

This body of literature suggests an interesting perspective on theoretical models of opinion formation by interacting parties in a network: in addition to considering interventions that directly modify people's intrinsic opinions, it is also natural to consider interventions that modify people's susceptibility to persuasion.

Learning Networks from Random Walk-Based Node Similarities

1 code implementation23 Jan 2018 Jeremy G. Hoskins, Cameron Musco, Christopher Musco, Charalampos E. Tsourakakis

In this work we consider a privacy threat to a social network in which an attacker has access to a subset of random walk-based node similarities, such as effective resistances (i. e., commute times) or personalized PageRank scores.

Anomaly Detection Clustering +3

Minimizing Polarization and Disagreement in Social Networks

3 code implementations28 Dec 2017 Cameron Musco, Christopher Musco, Charalampos E. Tsourakakis

We perform an empirical study of our proposed methods on synthetic and real-world data that verify their value as mining tools to better understand the trade-off between of disagreement and polarization.

Recommendation Systems

Predicting Positive and Negative Links with Noisy Queries: Theory & Practice

1 code implementation19 Sep 2017 Charalampos E. Tsourakakis, Michael Mitzenmacher, Kasper Green Larsen, Jarosław Błasiok, Ben Lawson, Preetum Nakkiran, Vasileios Nakos

The {\em edge sign prediction problem} aims to predict whether an interaction between a pair of nodes will be positive or negative.

Clustering

ADAGIO: Fast Data-aware Near-Isometric Linear Embeddings

1 code implementation17 Sep 2016 Jarosław Błasiok, Charalampos E. Tsourakakis

We verify experimentally the efficiency of our method on numerous real-world datasets, where we find that our method ($<$10 secs) is more than 3\, 000$\times$ faster than the state-of-the-art method \cite{hedge2015} ($>$9 hours) on medium scale datasets with 60\, 000 data points in 784 dimensions.

Computational Efficiency Dimensionality Reduction

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