258 citations · 267 across the 20 of their papers we have counts for
22 papers
Graphical Analysis of Lifted Product Code Constructions
Ragnar Freij-Hollanti, Kirsten D. Morris, Patricija Šapokaitė
Lifted product codes are an important family of quantum low-density parity-check (QLDPC) codes, as they were the first QLDPC code family shown to be asymptotically good. Understand…
Attacking the Polynomials in the Maze of Finite Fields problem
Àngela Barbero, Ragnar Freij-Hollanti, Camilla Hollanti +3
In April 2025 GMV announced a competition for finding the best method to solve a particular polynomial system over a finite field. In this paper we provide a method for solving the…
A -Polymatroid Framework for Information Leakage in Secure Linear Network Coding
Eimear Byrne, Johan Vester Dinesen, Ragnar Freij-Hollanti +1
We study information leakage in secure linear network coding schemes based on nested rank-metric codes. We show that the amount of information leaked to an adversary that observes…
The Star Product of Uniformly Random Codes
Johan Vester Dinesen, Ragnar Freij-Hollanti, Camilla Hollanti +2
We consider the problem of determining the expected dimension of the star product of two uniformly random linear codes that are not necessarily of the same dimension. We use a corr…
Perfectly-Private Analog Secure Aggregation in Federated Learning
Delio Jaramillo-Velez, Charul Rajput, Ragnar Freij-Hollanti +2
In federated learning, multiple parties train models locally and share their parameters with a central server, which aggregates them to update a global model. To address the risk o…
Secret Sharing in the Rank Metric
Johan Vester Dinesen, Eimear Byrne, Ragnar Freij-Hollanti +1
The connection between secret sharing and matroid theory is well established. In this paper, we generalize the concepts of secret sharing and matroid ports to -polymatroids. Spe…
Private Information Retrieval from Colluding and Byzantine Servers with Binary Reed-Muller Codes
Perttu Saarela, Matteo Allaix, Ragnar Freij-Hollanti +1
In this work, a flexible and robust private information retrieval (PIR) scheme based on binary non-maximum distance separable (non-MDS) codes is considered. This combines previous…
Information Hiding Using Matroid Theory
Ragnar Freij-Hollanti, Olga Kuznetsova
Inspired by problems in Private Information Retrieval, we consider the setting where two users need to establish a communication protocol to transmit a secret without revealing it…
Low-Rank Parity-Check Codes over the Ring of Integers Modulo a Prime Power
Julian Renner, Sven Puchinger, Antonia Wachter-Zeh +2
We define and analyze low-rank parity-check (LRPC) codes over extension rings of the finite chain ring , where is a prime and is a positive integer. LRPC…
Cyclic Flats of Binary Matroids
Ragnar Freij-Hollanti, Matthias Grezet, Camilla Hollanti +1
In this paper, first steps are taken towards characterising lattices of cyclic flats that belong to matroids that can be represented over a prescribed finite f…
Private Information Retrieval Schemes with Regenerating Codes
Julien Lavauzelle, Razane Tajeddine, Ragnar Freij-Hollanti +1
A private information retrieval (PIR) scheme allows a user to retrieve a file from a database without revealing any information on the file being requested. As of now, PIR schemes…
Cyclic Codes with Locality and Availability
Lukas Holzbaur, Ragnar Freij-Hollanti, Antonia Wachter-Zeh
In this work codes with availability are constructed based on the cyclic \emph{locally repairable code} (LRC) construction by Tamo et al. and their extension to -locality by…
Private Streaming with Convolutional Codes
Lukas Holzbaur, Ragnar Freij-Hollanti, Antonia Wachter-Zeh +1
Recently, information-theoretic private information retrieval (PIR) from coded storage systems has gained a lot of attention, and a general star product PIR scheme was proposed. In…
Robust Private Information Retrieval from Coded Systems with Byzantine and Colluding Servers
Razane Tajeddine, Oliver W. Gnilke, David Karpuk +2
A private information retrieval (PIR) scheme on coded storage systems with colluding, byzantine, and non-responsive servers is presented. Furthermore, the scheme can also be used f…
On Binary Matroid Minors and Applications to Data Storage over Small Fields
Matthias Grezet, Ragnar Freij-Hollanti, Thomas Westerbäck +1
Locally repairable codes for distributed storage systems have gained a lot of interest recently, and various constructions can be found in the literature. However, most of the cons…
Private Information Retrieval from Coded Databases with Colluding Servers
Ragnar Freij-Hollanti, Oliver Gnilke, Camilla Hollanti +1
We present a general framework for Private Information Retrieval (PIR) from arbitrary coded databases, that allows one to adjust the rate of the scheme according to the suspected n…
Network Resource Sharing Games with Instantaneous Reciprocity
Sofonias Hailu, Ragnar Freij-Hollanti, Alexis A. Dowhuszko +1
We propose a generic strategic network resource sharing game between a set of players representing operators. The players negotiate which sets of players share given resources, ser…
Warmth and connectivity of neighborhood complexes of graphs
Anton Dochtermann, Ragnar Freij-Hollanti
In this paper we study a pair of numerical parameters associated to a graph . One the one hand, one can construct , a space of homomorphisms from a edge $K_2…
Degrees of Freedom and Secrecy in Wireless Relay Networks
Arsenia Chorti, Ragnar Freij, David Karpuk
We translate the problem of designing a secure communications protocol for several users communicating through a relay in a wireless network into understanding certain subvarieties…
Face numbers of centrally symmetric polytopes from split graphs
Ragnar Freij, Matthias Henze, Moritz W. Schmitt +1
We analyze a remarkable class of centrally symmetric polytopes, the Hansen polytopes of split graphs. We confirm Kalai's 3^d-conjecture for such polytopes (they all have at least 3…
Partially ordered secretaries
Ragnar Freij, Johan Wästlund
The elements of a finite nonempty partially ordered set are exposed at independent uniform times in to a selector who, at any given time, can see the structure of the induc…
Enumeration of derangements with descents in prescribed positions
Niklas Eriksen, Ragnar Freij, Johan Wastlund
We enumerate derangements with descents in prescribed positions. A generating function was given by Guo-Niu Han and Guoce Xin in 2007. We give a combinatorial proof of this result,…