The committee for the 2026 Principles of Distributed Computing Doctoral Dissertation Award has decided to share the award between two recipients:
- Dr. Diana Ghinea, for her dissertation “Convex Validity“
- Dr. Jovan Komatovic, for his dissertation “Optimal Byzantine Agreement with Little Cryptography“
Dr. Ghinea completed her Doctor of Sciences degree at ETH Zürich under the supervision of Roger Wattenhofer, and Dr. Komatovic completed his Doctor of Sciences degree at the École Polytechnique Fédérale de Lausanne (EPFL) under the supervision of Rachid Guerraoui.
Both theses address fundamental questions in distributed consensus under Byzantine faults, with a shared emphasis on handling large or complex value domains and improving efficiency beyond classical formulations. However, they take notably different conceptual directions and emphasize different technical axes. The committee views the two theses as complementary and necessary to advance the classic problem of Byzantine agreement to timely domains, within both theory and applications.
Dr. Ghinea’s dissertation addresses a well-known limitation of Byzantine agreement, where the agreed upon values do not necessarily represent the honest participants’ inputs. It departs from standard consensus and instead studies convex agreement, where the outputs need to be in the honest inputs’ convex hull, and its relaxed variant approximate agreement, which allows the outputs to be “close” rather than identical. This shift enables a rich exploration of agreement under different interpretations of closeness and validity. A central contribution is the development of the honest core technique, extending classical core-set ideas to guarantee stronger properties in synchronous executions while maintaining robustness in mixed (synchronous-asynchronous) settings. The thesis spans both the mixed-setting network-agnostic model and synchronous systems, combining deep geometric insights (convexity spaces and Helly numbers) with algorithmic design. It culminates in improved complexity bounds for convex and standard Byzantine agreement, including communication-efficient and adversary-resilient protocols. The framework ensures that decision values are meaningful. This is relevant for applications such as distributed sensing, federated learning, and data-driven systems. Overall, the work is conceptually ambitious and coherent, pushing the boundaries of how agreement itself is defined.
Dr. Komatovic’s thesis focuses on efficient exact Byzantine agreement for large input domains, with a primary goal of reducing communication complexity by minimizing reliance on heavy cryptographic primitives, which bring concerns of scalability and fragility in addition to cost. The unifying technical tool is graded consensus, extended in novel ways to handle large values and intermediate “graded inputs.” Across asynchronous, partially synchronous, and synchronous models, the thesis develops protocols that approach optimal communication, time, and bit complexity, including hash-based compression techniques and transformations that preserve complexity across models. The asynchronous part, in particular, introduces highly efficient randomized algorithms, which are later generalized and systematized. The dissertation is technically strong and cohesive, with clear practical motivation (e.g., for blockchain systems and distributed environments where cryptographic overhead is a concern) and a consistent focus on efficiency improvements within the classical consensus framework. This work is not centered on a single conceptual breakthrough, yet its strength is in a broad technical landscape that has the potential of bridging theory and practice: It presents tools and increases understanding that just may have impact on further research and real-world implementations.
The award is sponsored jointly by the ACM Symposium on Principles of Distributed Computing (PODC) and the EATCS Symposium on Distributed Computing (DISC). It is presented annually, with the presentation taking place alternately at PODC and DISC. This year it will be presented at DISC, to be held in Rome, Italy, November 9-13, 2026.
The 2026 Principles of Distributed Computing Doctoral Dissertation Award Committee:
- Hagit Attiya, Technion
- Dariusz Kowalski, Augusta University
- Fabian Kuhn, University of Freiburg
- Andréa W. Richa (chair), Arizona State University
- Alex Schwarzmann, Augusta University