# Stockholm Mathematics Centre Prizes for Excellent Doctoral Dissertation and Master Theses 2014/2015

## Excellent PhD Thesis

SMC's prize for excellent PhD Thesis in Mathematics 2014/2015 is shared between Daniel Bergh and Martin Strömqvist

**Daniel Bergh**

*Thesis title:* Destackification and Motivic Classes of Stacks

*Advisor: *David Rydh

*Motivation:* Daniel Bergh receives the prize for a doctoral thesis in algebraic geometry, that with keen skill and a wide range of techniques treats the Grothendieck group of stacks, as well as giving an important algorithmic construction of destackification for certain algebraic stacks.

**Martin Strömqvist**

*Thesis title: * Homogenization in Perforated Domains

*Advisor:* Henrik Shahgholian, John Andersson (biträdande)

*Motivation:* Martin Strömqvist receives the prize for a doctoral thesis which makes significant progress on difficult and highly technical problems in homogenization of randomly perforated materials with thin obstacles.

## Excellent Master Thesis

*SMC's prize for excellent Master Thesis in Mathematics 2014/2015* is awarded to Szymon Albinski, Johan Lindberg and Oscar Mickelin.

**Thesis title: A branch-and-cut method for the Vehicle Relocation Problem in the One-Way Car-Sharing**

*Advisors:* Michael Ritter (TU München), Wolfgang Riedl (TU München)

*Examiners:* Peter Gritzmann (TU München), Anders Forsgren (KTH)

The master's thesis of **Szymon Albinski** addresses a practical problem that car pools are facing, namely that cars are parked in areas of low demand and need to be relocated to areas of high demand. Albinski has formulated the problem mathematically as a mixed-integer linear programming problem, shown that it is NP-complete, developed a branch-and-cut method and evaluated the approach on several test cases. This thesis demonstrates a deep understanding of mathematical modelling, optimization and scientific competence.

The work has been carried out at TU München for a double degree at TU München and KTH.

**Thesis title: Equivariant Sheaves on Topological Categories**

*Advisor: *Henrik Forssel

**Johan Lindberg's** master's thesis in category theory and logic gives a carefully structured and highly readable account of important results in topos theory. Lindberg treats results that previously existed either scattered in the literature or as folklore, and he gives independent proofs that improve the generality of many of the results. The thesis demonstrates not only a solid mastery of difficult technical material, but also a remarkably mature perspective on the area of study.

**Thesis title: On Spectral Inequalities in Quantum Mechanics and Conformal Field Theory**

*Advisor:* Ari Laptev

**Oscar Mickelin’s** very well-written thesis displays impressive mathematical maturity and a thorough understanding of difficult material from spectral theory and mathematical physics. Mickelin’s thesis is split into two parts. The first deals with Lieb-Thirring type inequalities for one-dimensional Schrodinger type operators. Mickelin generalises a paper of Exner, Laptev and Usman by considering different boundary conditions and by including a magnetic-type term. This part of the thesis has already been published in Bulletin of Mathematical Sciences. The second part of the thesis deals with spectral asymptotics and spectral estimates a discrete Schrödinger operators that appear in the Conformal Field Theory.