Successfully Defended My Ph.D. Dissertation

Nov 24, 2025·
Naram Mhaisen
Naram Mhaisen
blog

On 24 November 2025, I successfully defended my Ph.D. dissertation, “Optimistic Learning with Applications to Caching Networks,” at Delft University of Technology.

The work was carried out in the Networked Systems Group, under the supervision of Prof. dr. K. G. Langendoen (promotor) and Dr. G. Iosifidis (copromotor).

The thesis at a glance

The thesis asks how sequential decision-making algorithms can leverage untrusted predictions while still maintaining worst-case guarantees. Its central application is caching in content delivery networks, where the proposed algorithms are validated experimentally on multiple established datasets and benchmarks. Each chapter addresses this question under a progressively richer benchmark: static regret for coded caching, α-static regret for whole-file caching, dynamic regret for tracking a moving target, and policy regret for systems with memory.

Technical progression of the thesis chapters: optimistic learning under static, alpha-static, dynamic, and policy regret, with the actions and comparator of each chapter.
Technical progression of the chapters. Each chapter adopts a distinct regret metric suited to its actions set and choice of comparator(s).

Materials

Doctoral Committee

  • Rector Magnificus, Chairman
  • Prof. dr. K. G. Langendoen, Delft University of Technology — promotor
  • Dr. G. Iosifidis, Delft University of Technology — copromotor

Independent Members

  • Prof. dr. G. Dán, KTH Royal Institute of Technology, Sweden
  • Prof. dr. P. Grosso, University of Amsterdam
  • Prof. dr. M. T. J. Spaan, Delft University of Technology
  • Prof. dr. T. Spyropoulos, Technical University of Crete, Greece
  • Dr. T. A. L. van Erven, University of Amsterdam

I am deeply grateful to my promotors, the members of the committee, my colleagues, and my family for their support throughout this journey.