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  • Study location Delta, Mälardalen University Västerås or Zoom
  • 2020-11-20 10:15–13:00

The public defence of Pitos Seleka Biganda´s doctoral thesis in Mathematics/Applied Mathematics

The public defense of Pitos Seleka Biganda´s doctoral thesis in Mathematics/Applied Mathematics will take place at 10.15 on November 20, 2020.

Title: “Analytical and interative methods of computing”.

Serial number: 325.

The faculty examiner is Professor Oleg Seleznjev, Umeå University. The examining committee consists of Associate Professor Olga Liivapuu, Estonian University of Life Sciences, Associate Professor Andriy Andreev, Stockholm University, Professor Vladimir Anisimo, Center for Design and Analysis at Amgen Inc.

Reserve: Professor Kimmo Eriksson, Mälardalen University and Associate Professor Oleksandr Borisenko, Taras Shevchenko National University of Kyiv.

The doctoral thesis has serial number 325.


This thesis is about variants of PageRank, methods of PageRank computation and perturbation analysis of a PageRank vector as a stationary distribution of a kind of perturbed Markov chain model. Chapter 2 of this thesis gives closed form formulae for ordinary and lazy PageRanks for some specific simple line graphs. Different cases of changes made to the simple line graph are considered and for each case, a corresponding formula for each of the two variants of PageRank is provided.Chapter 3 is dedicated to the exploration of relationships that exist between three known variants of PageRank: ordinary PageRank, lazy PageRank and random walk with backstep PageRank in terms of their convergence and consistency in rank scores for different graph structures with reference to PageRank parameters, the damping factor c and backstep parameter β. In Chapter 4, we discuss numerical methods used in solving the PageRank problem as a linear system and evaluate some stopping criteria that can be employed in such methods. Finally, in Chapter 5, we address the PageRank problem as a first order perturbed Markov chain problem and study the perturbation analysis for stationary distributions of Markov chains with damping component. We illustrate our results on asymptotic perturbation analysis by using different computational examples.

“Analytical and interative methods of computing” full text (DiVA)external link

Register to take part

To be able to participate in the PhD defense, you need to pre-apply to administrative research support staff Marja Mutikainen marja.mutikainen@mdh.se by informing your name and e-mail. You also need to inform if you wish to take part in Zoom or in Delta. Last day to register is November 19, 2020. 

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