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Employee Profile

Runar Ile

Associate Professor - Department of Economics

Room number B3Y-087
Phone +4796906509
E-mail runar.ile@bi.no

Area of Expertise

Mathematics

Publications

Scientific publications Other

Ile, Runar (2021)

Deformation theory of Cohen-Macaulay approximation

Journal of Algebra, 568, s. 437- 466. Doi: 10.1016/j.jalgebra.2020.09.039 - Full text in research archive

In [22] we established axiomatic parametrised Cohen-Macaulay approximation which in particular was applied to pairs consisting of a finite type flat family of Cohen-Macaulay rings and modules. In this sequel we study the induced maps of deformation functors and deduce properties like smoothness and injectivity under general, mainly cohomological conditions on the module.

Gustavsen, Trond Stølen & Ile, Runar (2018)

Deformations of rational surface singularities and reflexive modules with an application to flops

Advances in Mathematics, 340, s. 1108- 1140. Doi: 10.1016/j.aim.2018.10.023 - Full text in research archive

Blowing up a rational surface singularity in a reflexive module gives a (any) partial resolution dominated by the minimal resolution. The main theorem shows how deformations of the pair (singularity, module) relates to deformations of the corresponding pair of partial resolution and locally free strict transform, and to deformations of the underlying spaces. The results imply some recent conjectures on small resolutions and flops.

Ile, Runar (2014)

Stably reflexive modules and a lemma of Knudsen

Journal of Algebra, 397, s. 141- 167. Doi: 10.1016/j.jalgebra.2013.08.024

Ile, Runar (2012)

Cohen-Macaulay approximation in fibred categories

Journal of Algebra, 367, s. 142- 165. Doi: 10.1016/j.jalgebra.2012.06.006

Gustavsen, Trond Stølen & Ile, Runar (2011)

The deformation relation on the set of Cohen-Macaulay modules on a quotient surface singularity

Banach Center Publications, 93, s. 41- 50. Doi: 10.4064/bc93-0-3

Gustavsen, Trond Stølen & Ile, Runar (2010)

Representation theory for log-canonical surface singularities

Annales de l'Institut Fourier, 60(2), s. 389- 416. Doi: 10.5802/aif.2526

Gustavsen, Trond Stølen & Ile, Runar (2008)

Reflexive modules on normal surface singularities and representations of the local fundamental group

Journal of Pure and Applied Algebra, 212(4), s. 851- 862. Doi: 10.1016/j.jpaa.2007.07.002

Ile, Runar (2007)

Deforming syzygies of liftable modules and generalised Knörrer functors

Collectanea Mathematica, 58(3), s. 255- 277.

Ile, Runar (2004)

Change of rings in deformation theory of modules

Transactions of the American Mathematical Society, 356(12), s. 4873- 4896.

Ile, Runar (2004)

Deformation Theory of Rank 1 maximal Cohen-Macaulay Modules on Hypersurface Singularities and the Scandinavian Complex

Compositio Mathematica, 140(2), s. 435- 446.

Gustavsen, Trond Stølen & Ile, Runar (2004)

The versal deformation space of a reflexive module on a rational cone

Journal of Algebra, 279(2), s. 613- 637.

Gustavsen, TS & Ile, Runar (2004)

The versal deformation space of a reflexive module on a rational cone

Journal of Algebra, 279, s. 613- 637.

Ile, Runar (2004)

Change of rings in deformation theory of modules

Transactions of the American Mathematical Society, 356, s. 4873- 4896.

Ile, Runar (2004)

Deformation theory of rank one maximal Cohen-Macaulay modules on hypersurface singularities and the Scandinavian complex

Compositio Mathematica, 140, s. 435- 446.

Ile, Runar (2004)

Deformation theory of reflexive modules on rational surface singularities II

[Academic lecture]. utenTitteltekst.

Ile, Runar (2004)

Nøkkellemma

[Academic lecture]. utenTitteltekst.

Ile, Runar (2004)

Introduction to the Weil conjectures

[Academic lecture]. utenTitteltekst.

Ile, Runar (2004)

Deforming syzygies of liftable modules and generalised Knörrer functors

[Report]. Dept. of Math.., University of Oslo.

Gustavsen, Trond Stølen & Ile, Runar (2004)

The versal deformation space of a maximal Cohen-Macaulay module on a simple singularity

[Report]. Dept. of Math.., University of Oslo.

Ile, Runar (2003)

Change of rings in deformation theory of modules

[Report]. Dept. of Math.., University of Oslo.

Gustavsen, Trond Stølen & Ile, Runar (2003)

The versal base space of a reflexive module on a rational cone

[Report]. Universitetet i Oslo. Matematisk institutt.

By an approach based on results of A. Ishii, we describe the versal deformation space of any reflexive module on the cone over the rational normal curve of degree m. To each component a resolution is given as the total space of a vector bundle on a Grassmannian. The vector bundle is a sum of copies of the cotangent bundle, the canonical sub-bundle, the dual of the canonical quotient bundle, and the trivial line bundle. Via an embedding in a trivial bundle, we obtain the components by projection. In particular we give equations for the minimal stratum in the Chern class filtration of the versal deformation space. We obtain a combinatorial description of the local deformation relation and a classification of the components. In particular we give a formula for the number of components.

Ile, Runar (2002)

Deformation theory of rank 1 maximal Cohen-Macaulay modules on hypersurface singularities and the Scandinavian complex

[Report]. Dept. of Math.., University of Oslo.

Academic Degrees
Year	Academic Department	Degree
2001	University of Oslo	Ph.D.
1990	University of Oslo	Candidatus scientiarum

Work Experience
Year	Employer	Job Title
2017 - Present	BI Norwegian Business School, Department of Economics	Associate professor
2017 - Present	University of Bergen, Department of Mathematics	Associate professor (adjunct position)
2017 - Present	University of Oslo	External advisor to the bachelor program «Mathematics with informatics» at the Department of Mathematics
2005 - 2016	University of Bergen, Department of Mathematics	Associate professor
2011 - 2012	KTH Royal Institute of Technology, Department of Mathematics	Visiting Associate professor (with support from the Kurt and Alice Wallenberg foundation)
1999 - 2005	University College of Hedmark	Associate professor
2003 - 2004	University of Oslo	Guest researcher under the SUPREMA program
2002 - 2003	Norwegian University of Science and Technology, Department of Mathematical Sciences	Associate professor