The geometry of blueprints. Part I: Algebraic background and scheme theory

In this paper, we introduce the category of blueprints, which is a category of algebraic objects that include both commutative (semi)rings and commutative monoids. This generalization allows a simultaneous treatment of ideals resp.\ congruences for rings and monoids and leads to a common scheme theory. In particular, it bridges the gap between usual schemes and $\mathbb{F}_1$-schemes (after Kato, Deitmar and Connes-Consani). Beside this unification, the category of blueprints contains new interesting objects as "improved" cyclotomic field extensions $\mathbb{F}_{1^n}$ of $\mathbb{F}_1$ and "archimedean valuation rings". It also yields a notion of semiring schemes. This first paper lays the foundation for subsequent projects, which are devoted to the following problems: Tits' idea of Chevalley groups over $\mathbb{F}_1$, congruence schemes, sheaf cohomology, $K$-theory and a unified view on analytic geometry over $\mathbb{F}_1$, adic spaces (after Huber), analytic spaces (after Berkovich) and tropical geometry.Comment: Slightly revised and extended version as in print. 51 page

The AKNS-hierarchy

We present here an overview for the Encyclopaedia of Mathematics of the various forms and properties of this system of equations together with its geometric and Lie algebraic background

Injectivity radius of representations of triangle groups and planar width of regular hypermaps

We develop a rigorous algebraic background for representations of triangle groups in linear groups over algebras arising from factor rings of multivariate polynomial rings. This is then used to substantially improve the existing bounds on the order of epimorphic images of triangle groups with a given injectivity radius and, analogously, the size of the associated hypermaps of a given type with a given planar width

Flows and stochastic Taylor series in Ito calculus

For stochastic systems driven by continuous semimartingales an explicit formula for the logarithm of the Ito flow map is given. A similar formula is also obtained for solutions of linear matrix-valued SDEs driven by arbitrary semimartingales. The computation relies on the lift to quasi-shuffle algebras of formulas involving products of Ito integrals of semimartingales. Whereas the Chen-Strichartz formula computing the logarithm of the Stratonovich flow map is classically expanded as a formal sum indexed by permutations, the analogous formula in Ito calculus is naturally indexed by surjections. This reflects the change of algebraic background involved in the transition between the two integration theories

Algebraic Structures in the Coupling of Gravity to Gauge Theories

This article is an extension of the author's second master thesis [1]. It aims to introduce to the theory of perturbatively quantized General Relativity coupled to Spinor Electrodynamics, provide the results thereof and set the notation to serve as a starting point for further research in this direction. It includes the differential geometric and Hopf algebraic background, as well as the corresponding Lagrange density and some renormalization theory. Then, a particular problem in the renormalization of Quantum General Relativity coupled to Quantum Electrodynamics is addressed and solved by a generalization of Furry's Theorem. Next, the restricted combinatorial Green's functions for all two-loop propagators and all one-loop divergent subgraphs thereof are presented. Finally, relations between these one-loop restricted combinatorial Green's functions necessary for multiplicative renormalization are discussed. Keywords: Quantum Field Theory; Quantum Gravity; Quantum General Relativity; Quantum Electrodynamics; Perturbative Quantization; Hopf Algebraic RenormalizationComment: 57 pages, 259 Feynman diagrams, article; minor revisions; version to appear in Annals of Physic

Supersymmetric extension of Moyal algebra and its application to the matrix model

We construct operator representation of Moyal algebra in the presence of fermionic fields. The result is used to describe the matrix model in Moyal formalism, that treat gauge degrees of freedom and outer degrees of freedom equally.Comment: to appear in Mod.Phys.Let

Algorithms for Determining the Order of the Group of Points on an EllipticCurve with Application in Cryptography

Eliptické křivky jsou rovinné křivky, jejíž body vyhovují Weierstrassově rovnici. Jejich hlavní využití je v kryptografii, kde představují důležitý nástroj k tvorbě těžko rozluštitelných kódů bez znalosti klíče, který je v porovnání s ostatními šifrovacími systémy krátký. Díky těmto přednostem jsou hojně využívány. Abychom mohli kódovat a dekódovat zprávy v systému eliptických křivek, musíme znát řád dané eliptické křivky. K jeho získání se mimo jiné používá Shanksův algoritmus a jeho vylepšená varianta, Mestreho algoritmus.The elliptic curves are plane curves whose points satisfy the Weierstrass equation. Their main application is in the cryptography, where they represent an important device for creating code which is hard to break without knowing the key and which is short in comparison with other encoding methods. The elliptic curves are widely used thanks to these advantages. To be able to code and decode in the elliptic curve cryptography we must know the order of the given elliptic curve. The Shank's algorithm and its improved version, the Mestre's algorithm, are used for its determining.