Professor Iain Stewart's Outputs (20)

Reconfigurable routing in data center networks (2024)
Presentation / Conference Contribution
Kutner, D. C., & Stewart, I. A. (2024, September). Reconfigurable routing in data center networks. Presented at 20th International Symposium on Algorithmics of Wireless Networks, ALGOWIN 2024, Egham, UK

A hybrid network is a static (electronic) network that is augmented with optical switches. The Reconfigurable Routing Problem (RRP) in hybrid networks is the problem of finding settings for the optical switches augmenting a static network so as to ac... Read More about Reconfigurable routing in data center networks.

Payment scheduling in the Interval Debt Model (2023)
Presentation / Conference Contribution
Friedetzky, T., Kutner, D., Mertzios, G., Stewart, I., & Trehan, A. (2023, January). Payment scheduling in the Interval Debt Model. Presented at 48th International Conference on Current Trends in Theory and Practice of Computer Science (SOFSEM 2023), Novy Smokovec, Slovakia

The networks-based study of financial systems has received considerable attention in recent years, but seldom explicitly incorporated the dynamic aspects of such systems. We consider this problem setting from the temporal point of view, and we introd... Read More about Payment scheduling in the Interval Debt Model.

Routing packets on DPillar data centre networks (2015)
Presentation / Conference Contribution
Kiasari, A., Navaridas, J., & Stewart, I. (2015, December). Routing packets on DPillar data centre networks. Presented at 15th International Conference on Algorithms and Architectures for Parallel Processing, ICA3PP, Zhangjiajie, China

An efficient shortest path routing algorithm in the data centre network DPillar (2015)
Presentation / Conference Contribution
Erickson, A., Kiasari, A., Navaridas, J., & Stewart, I. (2015, December). An efficient shortest path routing algorithm in the data centre network DPillar. Presented at 9th Annual International Conference on Combinatorial Optimization and Applications, COCOA, Houston, USA

DPillar has recently been proposed as a server-centric data centre network and is combinatorially related to the well-known wrapped butterfly network. We explain the relationship between DPillar and the wrapped butterfly network before proving a symm... Read More about An efficient shortest path routing algorithm in the data centre network DPillar.

On the mathematics of data centre network topologies (2015)
Presentation / Conference Contribution
Stewart, I. (2015, August). On the mathematics of data centre network topologies. Presented at 20th International Symposium on Fundamentals of Computation Theory, Gdańsk, Poland

In a recent paper, combinatorial designs were used to construct switch-centric data centre networks that compare favourably with the ubiquitous (enhanced) fat-tree data centre networks in terms of the number of servers within (given a fixed server-to... Read More about On the mathematics of data centre network topologies.

Routing algorithms for recursively-defined data centre networks (2015)
Presentation / Conference Contribution
Erickson, A., Kiasari, A., Navaridas, J., & Stewart, I. (2015, December). Routing algorithms for recursively-defined data centre networks. Presented at 13th IEEE International Symposium on Parallel and Distributed Processing with Applications, Helsinki

The server-centric data centre network architecture can accommodate a wide variety of network topologies. Newly proposed topologies in this arena often require several rounds of analysis and experimentation in order that they might achieve their full... Read More about Routing algorithms for recursively-defined data centre networks.

Improved routing in the data centre networks HCN and BCN (2014)
Presentation / Conference Contribution
Stewart, I. (2014, December). Improved routing in the data centre networks HCN and BCN. Presented at 2nd International Symposium on Computing and Networking - Across Practical Development and Theoretical Research, Shizuoka, Japan

Accelerating ant colony optimization-based edge detection on the GPU using CUDA (2014)
Presentation / Conference Contribution
Dawson, L., & Stewart, I. (2014, July). Accelerating ant colony optimization-based edge detection on the GPU using CUDA. Presented at 2014 IEEE Congress on Evolutionary Computation (CEC), Beijing, China

Ant Colony Optimization (ACO) is a nature-inspired metaheuristic that can be applied to a wide range of optimization problems. In this paper we present the first parallel implementation of an ACO-based (image processing) edge detection algorithm on t... Read More about Accelerating ant colony optimization-based edge detection on the GPU using CUDA.

Candidate set parallelization strategies for Ant Colony Optimization on the GPU (2013)
Presentation / Conference Contribution
Dawson, L., & Stewart, I. (2013, December). Candidate set parallelization strategies for Ant Colony Optimization on the GPU. Presented at 13th International Conference on Algorithms and Architectures for Parallel Processing, ICA3PP'13, Vietri sul Mare

For solving large instances of the Travelling Salesman Problem (TSP), the use of a candidate set (or candidate list) is essential to limit the search space and reduce the overall execution time when using heuristic search methods such as Ant Colony O... Read More about Candidate set parallelization strategies for Ant Colony Optimization on the GPU.

Improving Ant Colony Optimization performance on the GPU using CUDA. (2013)
Presentation / Conference Contribution
Dawson, L., & Stewart, I. (2013, December). Improving Ant Colony Optimization performance on the GPU using CUDA. Presented at 2013 IEEE Congress on Evolutionary Computation, Cancun, Mexico

We solve the Travelling Salesman Problem (TSP) using a parallel implementation of the Ant System (AS) algorithm for execution on the Graphics Processing Unit (GPU) using NVIDIA CUDA. Extending some recent research, we implement both the tour construc... Read More about Improving Ant Colony Optimization performance on the GPU using CUDA..

Graph editing to a fixed target (2013)
Presentation / Conference Contribution
Golovach, P., Paulusma, D., & Stewart, I. A. (2013, December). Graph editing to a fixed target. Presented at International Workshop on Combinatorial Algorithms, Rouen, France

For a fixed graph H, the H-Minor Edit problem takes as input a graph G and an integer k and asks whether G can be modified into H by a total of at most k edge contractions, edge deletions and vertex deletions. Replacing edge contractions by vertex di... Read More about Graph editing to a fixed target.

Node-to-node disjoint paths in k-ary n-cubes with faulty edges. (2012)
Presentation / Conference Contribution
Xiang, Y., Stewart, I., & Madelaine, F. (2012, January). Node-to-node disjoint paths in k-ary n-cubes with faulty edges. Presented at 17th International Conference on Parallel and Distributed Systems, ICPADS'11., Tainan, Taiwan

Let u and v be any two given nodes in a k-ary n-cube Qnk with at most 2n-2 faulty edges. Suppose that the number of healthy links incident with u is no more than that of v, and denote this number by m. In this paper, we show that there are m mutually... Read More about Node-to-node disjoint paths in k-ary n-cubes with faulty edges..

Hamiltonian cycles through prescribed edges in k-ary n-cubes. (2011)
Presentation / Conference Contribution
Stewart, I. (2011, December). Hamiltonian cycles through prescribed edges in k-ary n-cubes. Presented at 5th Annual International Conference on Combinatorial Optimization and Applications, COCOA'11., Zhangjiajie, China

We prove that if P is a set of at most 2n − 1 edges in a k-ary n-cube, where k ≥ 4 and n ≥ 2, then there is a Hamiltonian cycle on which every edge of P lies if, and only if, the subgraph of the k-ary n-cube induced by the edges of P is a vertex-disj... Read More about Hamiltonian cycles through prescribed edges in k-ary n-cubes..

Color image edge detection based on quantity of color information and implementation on the GPU. (2011)
Presentation / Conference Contribution
Zhao, J., Xiang, Y., Dawson, L., & Stewart, I. (2011, December). Color image edge detection based on quantity of color information and implementation on the GPU. Presented at 23rd IASTED International Conference on Parallel and Distributed Computing and Systems, PDCS'11., Dallas, USA

In this paper, we present a new method for quantifying color information so as to detect edges in color images. Our method uses the volume of a pixel in the HSI color space, allied with noise reduction, thresholding and edge thinning. We implement ou... Read More about Color image edge detection based on quantity of color information and implementation on the GPU..

Frameworks for logically classifying polynomial-time optimisation problems (2010)
Presentation / Conference Contribution
Gate, J., & Stewart., I. (2010, June). Frameworks for logically classifying polynomial-time optimisation problems. Presented at 5th International Computer Science Symposium in Russia (CSR 2010), Kazan, Russia

We show that a logical framework, based around a fragment of existential second-order logic formerly proposed by others so as to capture the class of polynomially-bounded P-optimisation problems, cannot hope to do so, under the assumption that P ≠ NP... Read More about Frameworks for logically classifying polynomial-time optimisation problems.

A general algorithm for detecting faults under the comparison diagnosis model (2010)
Presentation / Conference Contribution
Stewart, I. (2010, April). A general algorithm for detecting faults under the comparison diagnosis model. Presented at 24th IEEE International Parallel and Distributed Processing Symposium (IPDPS 2010), Atlanta, Georgia, U.S.A

We develop a widely applicable algorithm to solve the fault diagnosis problem in certain distributed-memory multiprocessor systems in which there are a limited number of faulty processors. In particular, we prove that if the underlying graph G = (V,E... Read More about A general algorithm for detecting faults under the comparison diagnosis model.

Pancyclicity and panconnectivity in augmented k-ary n-cubes (2009)
Presentation / Conference Contribution
Xiang, Y., & Stewart, I. (2009, December). Pancyclicity and panconnectivity in augmented k-ary n-cubes. Presented at The Fifteenth International Conference on Parallel and Distributed Systems : ICPADS'09, Shenzhen, China

The augmented k-ary n-cube AQ_{n,k} is a recently proposed interconnection network that incorporates an extension of a k-ary n-cube Q_n^k inspired by the extension of a hypercube Q_n to the augmented hypercube AQ_n (as developed by Choudom and Sunita... Read More about Pancyclicity and panconnectivity in augmented k-ary n-cubes.

Pancyclicity in faulty k-ary 2-cubes (2009)
Presentation / Conference Contribution
Xiang, Y., & Stewart, I. (2009, November). Pancyclicity in faulty k-ary 2-cubes. Presented at Proceedings of 21st International Conference on Parallel and Distributed Computing and Systems, PDCS'09., Cambridge, Massachusetts, USA

We prove that a k-ary 2-cube $Q_k^2$ with 3 faulty edges but where every vertex is incident with at least 2 healthy edges is bipancyclic, if k ≥ 3, and k-pancyclic, if k ≥ 5 is odd (these results are optimal).

The computational complexity of the parallel knock-out problem (2006)
Presentation / Conference Contribution
Broersma, H., Johnson, M., Paulusma, D., & Stewart, I. (2006, March). The computational complexity of the parallel knock-out problem. Presented at 7th Latin American Theoretical Informatics Symposium (LATIN 2006), Valdivia, Chile

We consider computational complexity questions related to parallel knock-out schemes for graphs. In such schemes, in each round, each remaining vertex of a given graph eliminates exactly one of its neighbours. We show that the problem of whether, for... Read More about The computational complexity of the parallel knock-out problem.

A generic greedy algorithm, partially-ordered graphs and NP-completeness (2001)
Presentation / Conference Contribution
Puricella, A., & Stewart, I. (2001, June). A generic greedy algorithm, partially-ordered graphs and NP-completeness. Presented at 27th International Workshop on Graph-Theoretic Concepts in Computer Science (WG 2001), Rostock, Germany

Let π be any fixed polynomial-time testable, non-trivial, hereditary property of graphs. Suppose that the vertices of a graph G are not necessarily linearly ordered but partially ordered, where we think of this partial order as a collection of (possi... Read More about A generic greedy algorithm, partially-ordered graphs and NP-completeness.