Ghislain Fourny


Last Name

Fourny

First Name

Ghislain

ORCID

0000-0001-8740-8866

Organisational unit

01259 - Lehre Informatik

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Publications1 - 10 of 28
  • Rumble: data independence when data is in a mess
    Item type: Working Paper
    Irimescu, Stefan; Berker Cikis, Can; Fourny, Ghislain; et al. (2019)
    arXiv
  • Evaluating Query Languages and Systems for High-Energy Physics Data
    Item type: Journal Article
    Graur, Dan; Müller, Ingo; Proffitt, Mason; et al. (2021)
    Proceedings of the VLDB Endowment
    In the domain of high-energy physics (HEP), query languages in general and SQL in particular have found limited acceptance. This is surprising since HEP data analysis matches the SQL model well: the data is fully structured and queried using mostly standard operators. To gain insights on why this is the case, we perform a comprehensive analysis of six diverse, general-purpose data processing platforms using an HEP benchmark. The result of the evaluation is an interesting and rather complex picture of existing solutions: Their query languages vary greatly in how natural and concise HEP query patterns can be expressed. Furthermore, most of them are also between one and two orders of magnitude slower than the domain-specific system used by particle physicists today. These observations suggest that, while database systems and their query languages are in principle viable tools for HEP, significant work remains to make them relevant to HEP researchers.
  • Games in Minkowski Spacetime
    Item type: Working Paper
    Fourny, Ghislain (2020)
    This paper contributes a new class of games called spacetime games with perfect information. In spacetime games, the agents make decisions at various positions in Minkowski spacetime. Spacetime games can be seen as the least common denominator of strategic games on the one hand, and dynamic games with perfect information on the other hand. Indeed, strategic games correspond to a configuration with only spacelike-separated decisions ("different rooms"). Dynamic games with perfect information, on the other hand, correspond to timelike-separated decisions ("in turn"). We show how to compute the strategic form and reduced strategic form of spacetime games. As a consequence, many existing solution concepts, such as Nash equilibria, rationalizability, individual rationality, etc, apply naturally to spacetime games. We introduce a canonical injection of the class of spacetime games with perfect information into the class of games in extensive form with imperfect information; we provide a counterexample showing that this is a strict superset. This provides a novel interpretation of a large number of games in extensive form with imperfect information in terms of the theory of special relativity, where non-singleton information sets arise from the finite speed of light. This framework can be a useful tool for reasoning in quantum foundations, where it is important whether decisions such as the choice of a measurement axis or the outcome of a measurement are spacelike- or timelike- separated. We look in particular at the special case of the Einstein-Podolsky-Rosen experiment with four decision points, and model a corresponding spacetime game structure.
  • The Status-Quo in nested data processing for high-energy physics
    Item type: Journal Article
    Graur, Dan; Müller, Ingo; Proffitt, Mason; et al. (2025)
    The VLDB Journal
    Nested data is valuable and ubiquitous. It is being generated in ever-increasing volumes across industrial and research environments and frequently contains valuable information that is extracted through analytical workloads. Despite its popularity and value, there is no clear-cut understanding of the status quo in analytical workloads for nested data in high-energy physics (HEP). In this paper, we seek to define the landscape of nested data processing in HEP by evaluating 10 systems and their query languages on the IRIS HEP ADL benchmark, a popular and representative HEP benchmark. We attempt not only to understand how well these systems perform from a query latency and scalability point of view but also from a query language usability perspective. The result of our evaluation paints an interesting and rather complex picture of existing solutions. Many of the evaluated systems are between one and two orders of magnitude slower than the domain-specific system used in HEP today, while a few of the commodity systems provide on-par performance at greater costs. Moreover, the evaluated query languages and dialects vary greatly in how naturally and concisely they can express nested query patterns. These observations suggest that while commodity data management systems and their query languages are viable tools for nested data processing, significant work remains to make them competitive with domain-specific solutions like those used by the HEP community.
  • A Note on Weakening Free Choice in Quantum Theory
    Item type: Working Paper
    Fourny, Ghislain (2019)
    The non-extensibility of quantum theory into a non-trivial, noncontextual deterministic theory is based on a strong assumption of free choice, in which the physicists pick a measurement axis independently of the rest of the world. This same strong assumption of free choice is at the core of Nashian game theory. However, recent game-theoretical research based on a weakened version of free choice lead to non-trivial solution concepts with desirable properties. In this note, we share our view that a similar change of assumption to the modelling of free choice in the foundations of quantum theory opens a non-trivial avenue of research towards a deterministic and non-trivial version of quantum theory with, at least in theory, an improved predictive power. At this point, this note is a draft that will be regularly updated and completed based on feedback and discussions.
  • Perfect Prediction in normal form: Superrational thinking extended to non-symmetric games
    Item type: Journal Article
    Fourny, Ghislain (2020)
    Journal of mathematical psychology
  • A Time Machine for XML
    Item type: Report
    Fourny, Ghislain; Florescu, Daniela; Kossmann, Donald; et al. (2011)
    Technical report
    With sinking storage costs, it becomes more and more feasible, and popular, to retain past versions of documents and data. While undoing changes is worthy, this becomes even more valuable if the data is queryable. Nowadays, there are two widespread version control paradigms: document versioning (SVN, git, etc.) and versioned databases. The former handles any kind of document, even binary, but only sees lines of text, so that the query capability is limited. The latter provide ne-grained temporal query capabilities on highly structured data - but storing everything in a relational database is not desirable. The goal of this paper is to provide a unied framework for eciently versioning, querying and updating not only data and documents, but also, inbetween, any kind of semi-structured information, like XML.We start with the XQuery programming language and meticulously extend its data model, its syntax and its processing model to make it seamlessly time-aware. We provide data structures and algorithms for the ecient implementation of such a versioning system. Finally, we show that there is no signicant performance loss for traditional queries when enriching an existing engine with versioning capabilities.
  • On the interpretation of quantum theory as games between physicists and nature played in Minkowski spacetime
    Item type: Working Paper
    Fourny, Ghislain (2024)
    arXiv
    In 2019, we introduced games in Minkowski spacetime as a generalization of game theory to special relativity that subsumes games in normal form (spacelike separation) and games in extensive form (timelike separation). Many concepts including Nash equilibria naturally extend to spacetime games. We also emphasized the importance of these games to model quantum experiments such as Bell experiments and more generally any adaptive measurements. Subsequent work suggested to formalize a special case of such games in terms of strategy presheaves. In the case that measurements have a unique causal bridge and if a natural cover is taken, we show that the two frameworks are isomorphic to each other and provide complementary perspectives. Spacetime games provide a visual and intuitive framework that also captures the distinction between joint experiments and either-or experiments, so that they are rich enough in their causal structure to imply a natural cover for the corresponding causal contextuality scenario. Based on this observation, we suggest to define the strategy presheaf directly based on the pure strategies (and restrictions thereof) of the spacetime game, and we show that the sheaf property obtains for the games at hand. The argument is rather simple and similar to event sheaves for the flat case. Finally, we explain how, in the other direction, the failure of the sheaf property on strategy distribution presheaves is consistent with our previous argument that Nash game theory is not compatible with quantum physics. This shows that the insights of the two frameworks, taken together, can contribute positively to the advancement of the field of quantum foundations.
  • JSONiq: The history of a query language
    Item type: Journal Article
    Florescu, Daniela; Fourny, Ghislain (2013)
    IEEE Internet Computing
  • Kripke Semantics of the Perfectly Transparent Equilibrium
    Item type: Working Paper
    Fourny, Ghislain (2018)
Publications1 - 10 of 28