Tannaka Theory over Sup-Lattices

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Jul 16, 2015 - We consider the inclusion of topoi shP ֒→ SPop given by the adjunction # ⊣ i. A sup-lattice M ∈ sℓ(shP) yields a sup-lattice iM ∈ SPop.
Tannaka Theory over Sup-Lattices PhD thesis1 - March 2015.

arXiv:1507.04772v1 [math.CT] 16 Jul 2015

Mart´ın Szyld, University of Buenos Aires, Argentina.

The main result of this thesis is the construction of a tannakian context over the category sℓ of sup-lattices, associated with an arbitrary Grothendieck topos, and the attainment of new results in tannakian representation theory from it. Although many results were obtained and published historically linking Galois and Tannaka theory (see introduction), these are different and less general since they assume the existence of Galois closures and work on Galois topos rather than on arbitrary topos. Instead we, when talking about Galois theory, mean the extension to arbitrary topos of the article [17], critical to get the results of this thesis. The tannakian context associated with a Grothendieck topos is obtained through the process of taking relations of its localic cover. Then, through an investigation and exhaustive comparison of the constructions of the Galois and Tannaka theories, we prove the equivalence of their fundamental recognition theorems (see section 8). Since the (bi)categories of relations of a Grothendieck topos were characterized in [3], a new recognition-type tannakian theorem (theorem 8.12) is obtained, essentially different from those known so far (see introduction). 1

Under the direction of Eduardo J. Dubuc (University of Buenos Aires, Argentina).

1

Introduction On Galois Theories. In SGA 1, Expos´e V section 4, “Conditions axiomatiques d’une theorie de Galois”, ([4], see also [10]) Grothendieck reinterprets Galois Theory as a F

theory for functors C −→ Ens