# Daniel Schäppi

## Research Interests

I am interested in category theory and its applications to algebraic geometry and algebraic topology. Currently my research is focused on the duality between geometric objects (schemes, group schemes, stacks) and their associated tensor categories.

## Papers and Preprints

- Daniel Schäppi, Descent via Tannaka duality, 2015
- Preprint (submitted)
- arXiv: 1505.05681 [math.AG]
- Daniel Schäppi, Constructing colimits by gluing vector bundles, 2015
- Preprint (submitted)
- arXiv: 1505.04596 [math.AG]
- Richard Garner and Daniel Schäppi, When coproducts are biproducts,
- Mathematical Proceedings of the Cambridge Philosophical Society, Volume 161, Issue 01, July 2016, pp 47-51
- arXiv: 1505.01669 [math.CT]
- Daniel Schäppi, Which abelian tensor categories are geometric?,
- Journal für die reine und angewandte Mathematik (Crelles Journal), DOI: 10.1515/crelle-2014-0053, July 2014
- arXiv: 1312.6358 [math.AG]
- Daniel Schäppi, Ind-abelian categories and quasi-coherent sheaves,
- Mathematical Proceedings of the Cambridge Philosophical Society, Volume 157, Issue 03, November 2014, pp 391-423
- arXiv: 1211.3678 [math.AG]
- Daniel Schäppi, A characterization of categories of coherent sheaves of certain algebraic stacks, 2012
- Preprint, accepted for publication in JPAA
- arXiv: 1206.2764 [math.AG]
- Daniel Schäppi, The formal theory of Tannaka duality, 2011
- Astérisque 357 (2013), viii+140 pages
- arXiv: 1112.5213 [math.CT]

## Slides

I have given talks about my work at the International Category Theory conferences in 2011 and 2013. The slides are available here and here.

## Notes

A precursor of the "formal theory" paper above, based on my Master's thesis, is available on the arXiv: 0911.0977 [math.CT]. One of my semester papers, written under the advice of Prof. U. Lang at ETH Zürich, forms part of arXiv: 0902.3831 [math.DG]. Finally, I wrote up a short note to prove that a symmetric monoidal category with the property that the coproduct of the unit object with itself exists and has a dual is necessarily semi-additive. This has now been incorporated in the joint paper "When coproducts are biproducts" with Richard Garner.