Papers by Claudia-lavinia Ignat
Contracts and Grants with Industry - RNTL Xwiki Concerto (2006-2009)
2018 IEEE 4th International Conference on Collaboration and Internet Computing (CIC), 2018
Many real-world applications can be modeled as signed directed graphs wherein the links between n... more Many real-world applications can be modeled as signed directed graphs wherein the links between nodes can have either positive or negative signs. Social networks can be modeled as signed directed graphs where positive/negative links represent trust/distrust relationships between users. In order to predict user behavior in social networks, several studies have addressed the link-sign prediction problem that predicts a link sign as positive or negative. However, the existing approaches do not take into account the time when the links were added which plays an important role in understanding the user relationships. Moreover, most of the existing approaches require the complete network information which is not realistic in modern social networks. Last but not least, these approaches are not adapted for dynamic networks and the link-sign prediction algorithms have to be reapplied each time the network changes. In this paper, we study the problem of link-sign prediction by combining random walks for graph sampling, Doc2Vec for node vectorization and Recurrent Neural Networks for prediction. The approach requires only local information and can be trained incrementally. Our experiments on the same datasets as state-ofthe-art approaches show an improved prediction. Index Terms-link-sign prediction, dynamic networks, recurrent neural networks, random walks, Doc2Vec • Epinions 1 is a product-rating social network [9]. Users of Epinions can write reviews and rate products. They also
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific ... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Collaboration Technologies and Social Computing, 2020
Collaborative editing (CE) became increasingly common, often compulsory in academia and industry ... more Collaborative editing (CE) became increasingly common, often compulsory in academia and industry where people work in teams and are distributed across space and time. We aim to study collaborative editing behavior in terms of collaboration patterns users adopt and in terms of a characterisation of conflicts, i.e. edits from different users that occur close in time and position in the document. The process of a CE can be split into several editing 'sessions' which are performed by a single author ('single-authored session') or several authors ('co-authored session'). This fragmentation process requires a pre-defined 'maximum time gap' between sessions which is not yet well defined in previous studies. In this study, we analysed CE logs of 108 collaboratively edited documents. We show how to establish a suitable 'maximum time gap' to split CE activities into sessions by evaluating the distribution of the time distance between two adjacent sessions. We studied editing activities inside each 'co-author session' in order to define potential conflicts in terms of time and position dimensions before they occur in the document. We also analysed how many of these potential conflicts become real conflicts. Findings show that potential conflicting cases are few. However, they are more likely to become real conflicts.
Lecture Notes in Computer Science, 2017
When people work collaboratively on a shared document, they have two contradictory requirements o... more When people work collaboratively on a shared document, they have two contradictory requirements on their editors that may affect the efficiency of their work. On the one hand, they would like to know what other people are currently doing on a particular part of the document. On the other hand, they would like to focus their attention on their own current work, with as little disturbance from the concurrent activities as possible. We present some features that help the user handle disturbance and awareness of concurrent updates. While collaboratively editing a shared document with other people, a user can create a focus region. The user can concentrate on the work in the region without being interfered with the concurrent updates of the other people. Occasionally, the user can preview the concurrent updates and select a number of these updates to be integrated into the local copy. We have implemented a collaborative editing subsystem in the GNU Emacs 5 text editor with the described features.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Special Issue: ECSCW 2018: The 16th European Conference on Computer-Supported Cooperative Work, The International Venue on Practice-centred Computing and the Design of Cooperation Technologies Claudia-Lavinia Ignat, Pernille Bjørn, Prasun Dewan
Distributed collaborative systems allow users to collaborate on a set of shared documents from an... more Distributed collaborative systems allow users to collaborate on a set of shared documents from any place, at any time and from any device. Examples of collaborative systems are wikis, version control systems or GoogleDrive. While 30 years ago when these collaborative systems were firstly developed they were used in scenarios involving only a small set of users such as for the writing of a research article, nowadays we notice a change in the scale from several users to a community of users. The large-scale collaboration is now possible due to advances in mobile and ubiquitous communication that enable users to be continuously connected and to the appropriation of existing tools by the users. However, existing collaborative systems face several challenges including privacy issues as personal user information is placed in the hands of large corporations and users have little control over the usage of their data, performance and coordination issues in the large-scale context. In this ta...
CRDTs (Conflict-free Replicated Data Types) have properties desirable for large-scale distributed... more CRDTs (Conflict-free Replicated Data Types) have properties desirable for large-scale distributed systems with variable network latency or transient partitions. With CRDT, data are always available for local updates and data states converge when the replicas have incorporated the same updates. Undo is useful for correcting human mistakes and for restoring system-wide invariant violated due to long delays or network partitions. There is currently no generally applicable undo support for CRDTs. There are at least two reasons for this. First, there is currently no abstraction that we can practically use to capture the relations between undo and normal operations with respect to concurrency and causality. Second, using inverse operations as the existing partial solutions, the CRDT designer has to hard-code certain rules and design a new CRDT for almost every operation that needs undo support. In this paper, we present an approach to generic support of undo for CRDTs. The approach consis...
Companion of the 2017 ACM Conference on Computer Supported Cooperative Work and Social Computing, 2017
Not long ago, real time collaborative editing (CE) systems were seen as a novelty to the average ... more Not long ago, real time collaborative editing (CE) systems were seen as a novelty to the average user, and a niche area of computer science research. Today, nothing could be further from the truth. Users are increasingly more connected and are creating more and more content online, on mobile devices, and in cloud based applications. Users are increasingly expecting collaborative editing functionalities in all of their applications. The focus of this year's workshop is: 1) to explore recent advances in the technologies that enable collaborative editing systems, 2) to evaluate the adoption of these technologies by commercial industry and the open source communities, and 3) to foster an exchange of ideas between CE researchers and end-user CE systems builders. The goal is to increase the adoption of recent technological advancements in CE research by practitioners and to have practitioners identify real-world challenges for future research.
Real-time collaborative editing allows multiple users to edit shared documents at the same time f... more Real-time collaborative editing allows multiple users to edit shared documents at the same time from different places. Existing real-time collaborative editors rely on a central authority that stores user data which is a perceived privacy threat. In this paper, we present MultiUser Text Editor (MUTE), a peer-to-peer web-based real-time collaborative editor without central authority disadvantages. Users share their data with the collaborators they trust without having to store their data on a central place. MUTE features high scalability and supports offline and ad-hoc collaboration.
Often collaborative graphical systems lag behind in features with well accepted single-user appli... more Often collaborative graphical systems lag behind in features with well accepted single-user applications. The frequently used operations of group/ungroup offered by almost every single-user graphical editor have not been considered by the collaborative graphical editing systems. In this paper we present an algorithm for consistency maintenance in collaborative graphical editing dealing not only with simple operations such as create, delete, move, change colour or position, but also with group/ungroup operations. The system relying on this algorithm is customizable, offering three policy modes for dealing with conflict: null-effect based policy, priority based policy and multi-versioning based policy.
Abstract. Existing solutions for the collaboration over XML documents are limited to a centralise... more Abstract. Existing solutions for the collaboration over XML documents are limited to a centralised architecture. In this paper we propose an approach for peer-to-peer collaboration over XML documents where users can work off-line on their document replica and synchronise in an ad-hoc manner with other users. Our algorithm for maintaining consistency over XML documents recursively applies the tombstone operational transformation approach over the document levels.
Computer Supported Cooperative Work (CSCW), May 21, 2018
This special issue of JCSCW is a collection of the long papers presented at ECSCW 2018, the 16th ... more This special issue of JCSCW is a collection of the long papers presented at ECSCW 2018, the 16th European Conference on Computer-Supported Cooperative Work: The International Venue on Practice-centred Computing and the Design of Cooperation Technologies, held in the period 4-8 June 2018 in Nancy, France. ECSCW is a series of international conferences on computer-supported cooperative work located in Europe and championed by EUSSET, the European Society for Socially Embedded Technologies.
2016 IEEE Trustcom/BigDataSE/ISPA, 2016
Trust game is a money exchange game that has been widely used in behavioral economics for studyin... more Trust game is a money exchange game that has been widely used in behavioral economics for studying trust and collaboration between humans. In this game, exchange of money is entirely attributable to the existence of trust between users. The trust game could be one-shot, i.e. the game ends after one round of money exchange, or repeated, i.e. it lasts several rounds. Predicting user behavior in the repeated trust game is of critical importance for the next movement of the partners. However, existing behavior prediction approaches uniquely rely on players personal information such as their age, gender and income and do not consider their past behavior in the game. In this paper, we propose a computational trust metric that is uniquely based on users past behavior and can predict the future behavior in repeated trust game. Our trust metric can distinguish between users having different behavioral profiles and is resistant to fluctuating user behavior. We validate our model by using an empirical approach against data sets collected from several trust game experiments. We show that our model is consistent with rating opinions of users, and our model can provide higher accuracy on predicting users' behavior compared with other naive models.
ACM SIGWEB Newsletter, 2016
Wikipedia is indeed a very important knowledge sharing platform. However, since its start in 2001... more Wikipedia is indeed a very important knowledge sharing platform. However, since its start in 2001, the quality of Wikipedia is questioned because its content is created potentially by everyone who can access to the Internet. Currently, the quality of Wikipedia articles is assessed by human judgement. The method is not scalable up to huge size and fast changing speed of Wikipedia today. An automatic quality classifier for Wikipedia articles is required to support users to choose high quality articles for reading and to notify authors for improving their products. While other existing approaches are based on manually predefined specific feature set, we present our approach of using deep learning to automatically represent Wikipedia articles for quality classification.
Resolving conflicts is a key issue in collaborative editing. The difficulty of this task grows wi... more Resolving conflicts is a key issue in collaborative editing. The difficulty of this task grows with the complexity of the document structure, and most of digital documents are not simple sequences of characters. This paper offers a new approach to handle conflict resolution automatically in a rich text document. This work uses Operational Transformation approach, and is based on a meaningful set of operations instead of primitive ones. This way, information about what the users precisely want to do is saved, and conflict resolution is more accurate.
Abstract. Existing solutions for the collaboration over XML documents are limited to a centralise... more Abstract. Existing solutions for the collaboration over XML documents are limited to a centralised architecture. In this paper we propose an approach for peer-to-peer collaboration over XML documents where users can work off-line on their document replica and synchronise in an ad-hoc manner with other users. Our algorithm for maintaining consistency over XML documents recursively applies the tombstone operational transformation approach over the document levels.
In recent years collaborative editing systems such as wikis, GoogleDocs and version control syste... more In recent years collaborative editing systems such as wikis, GoogleDocs and version control systems became very popular. In order to improve reliability, fault-tolerance and availability shared data is replicated in these systems. User misbehaviors can make the system inconsistent or bring corrupted updates to replicated data. Solutions to secure data history of state-based replication exist, however they are hardly applied to operation-based replication. In this paper we propose an approach to secure log in operation-based optimistic replication system. authenticators based on hash values and digital signatures are generated each time a site shares or receives new updates on replicas. authenticators secure logs with security properties of integrity and authenticity. We present in detail algorithms to construct and verify authenticators and we analyse their complexities. Author Keywords
Proceedings of the 13th International Symposium on Open Collaboration
Wikipedia is considered as the largest knowledge repository in the history of humanity and plays ... more Wikipedia is considered as the largest knowledge repository in the history of humanity and plays a crucial role in modern daily life. Assigning the correct quality class to Wikipedia articles is an important task in order to provide guidance for both authors and readers of Wikipedia. The manual review cannot cope with the editing speed of Wikipedia. An automatic classification is required to classify the quality of Wikipedia articles. Most existing approaches rely on traditional machine learning with manual feature engineering, which requires a lot of expertise and effort. Furthermore, it is known that there is no general perfect feature set because information leak always occurs in feature extraction phase. Also, for each language of Wikipedia, a new feature set is required. In this paper, we present an approach relying on deep learning for quality classification of Wikipedia articles. Our solution relies on Recurrent Neural Networks (RNN) which is an endto-end learning technique that eliminates disadvantages of feature engineering. Our approach learns directly from raw data without human intervention and is language-neutral. Experimental results on English, French and Russian Wikipedia datasets show that our approach outperforms state-of-the-art solutions.
Proceedings of the 17th Acm International Conference on Supporting Group Work, Oct 27, 2012
Within last years multi-synchronous collaborative editing systems became widely used. Multi-synch... more Within last years multi-synchronous collaborative editing systems became widely used. Multi-synchronous collaboration maintains multiple, simultaneous streams of activity which continually diverge and synchronized. These streams of activity are represented by means of logs of operations, i.e. user modifications. A malicious user might tamper his log of operations. At the moment of synchronization with other streams, the tampered log might generate wrong results. In this paper, we propose a solution relying on hash-chain based authenticators for authenticating logs that ensure the authenticity, the integrity of logs, and the user accountability. We present algorithms to construct authenticators and verify logs. We prove their correctness and provide theoretical and practical evaluations.
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Papers by Claudia-lavinia Ignat