Abstract. Over the field of one element, vector bundles over n-dimensional projective spaces are considered. It is shown that all line bundles are tensor powers of the Hopf bundle and all vector bundles are direct sums of line bundles. This is in complete analogy to the case of the projective line over an arbitrary classical field, but drastically simpler in comparison with projective spaces of higher dimensions.Mathematics Subject Classification (2010). Primary 14D20; 14J60, 14T99.
Keywords. Fields with one element, Vector bundles, Projective spaces.In recent years there has been quite a bit of activity concerning the field of one element, F 1 (see e.g. [2], [6], [7] and [9]). By now, there are different versions in existence, so C. Soulé's paper [8] and a number of others [3][4][5]10], all of them interrelated with each other. We follow here the approach of Anton Deitmar in [4], which is closest to standard algebraic geometry.The purpose of this paper is to study vector bundles over the projective line and, more generally, on n-dimensional projective space. As the classification of vector bundles on P 1 is rather immediately related with the Euclidean algorithm, it was our hope that something combinatorially interesting might show up in this context, as the underlying group here is the symmetric group.However it seems that the situation at least for this question is too simple. Over P 1 our result is identical with Grothendiecks result that any vector bundle on P 1 is a direct sum of line bundles. The latter are classified up to isomorphisms by their degree. The same holds true for vector bundles on P n over F 1 , so here the situation is drastically simpler than in the classical case.Formally, this project came up as the Diplom-thesis of the second author in (2008), written under guidance of the last and with crucial observations of the first author.