arXiv subjects

Uwe Schauz

Publications and source records attributed to Uwe Schauz.

10 recordsLinked to original sources

arXiv2024

Functional degrees and arithmetic applications III: Beyond Prime Exponent

Continuing our work on group-theoretic generalizations of the prime Ax-Katz Theorem, we give a lower bound on the $p$-adic divisibility of the cardinality of the set of simultaneous zeros $Z(f_1,f_2,\ldots,f_r)$ of $r$ maps $f_j:A\rightarrow B_j$ between arbitrary finite commutative groups $A$ and $B_j$ in terms of the invariant factors of $A, B_1,B_2,\dotsc,B_r$ and the \emph{functional degrees} of the maps $f_1,f_2,\dotsc,f_r$.

math.NT↗

arXiv2023

Functional degrees and arithmetic applications II: The Group-Theoretic Prime Ax-Katz Theorem

We give a version of Ax-Katz's $p$-adic congruences and Moreno-Moreno's $p$-weight refinement that holds over any finite commutative ring of prime characteristic. We deduce this from a purely group-theoretic result that gives a lower bound on the $p$-adic divisibility of the number of simultaneous zeros of a system of maps $f_j: A\to B_j$ from a fixed ``source'' finite commutative group $A$ of exponent $p$ to varying ``target'' finite commutative $p$-groups $B_j$. Our proof combines Wilson's proof of Ax-Katz over $\mathbb{F}_p$ with the functional calculus of Aichinger-Moosbauer.

math.GR↗

arXiv2021

The Largest Possible Finite Degree of Functions between Commutative Groups

We consider maps between commutative groups and their functional degrees. These degrees are defined based on a simple idea -- the functional degree should decrease if a discrete derivative is taken. We show that the maps of finite functional degree are precisely the maps that can be written as polyfracts, as polynomials in several variables but with binomial functions in the place of powers. Moreover, the degree of a polyfract coincides with its functional degree. We use this to determine the largest possible finite functional degree that the maps between two given finite commutative groups can have. This also yields a solution to Aichinger and Moosbauer's problem of finding the nilpotency degree of the augmentation ideal of the group ring $Z_{p^β}[Z_{p^{α_1}}\times Z_{p^{α_2}}\times\dots\times Z_{p^{α_n}}]$. Some generalizations and simplifications of proofs to underlying facts are presented, too.

math.GR↗

arXiv2021

Classification of Polynomial Mappings Between Commutative Groups

Some polynomials $P$ with rational coefficients give rise to well defined maps between cyclic groups, $\Z_q\longrightarrow\Z_r$, $x+q\Z\longmapsto P(x)+r\Z$. More generally, there are polynomials in several variables with tuples of rational numbers as coefficients that induce maps between commutative groups. We characterize the polynomials with this property, and classify all maps between two given finite commutative groups that arise in this way. We also provide interpolation formulas and a Taylor-type theorem for the calculation of polynomials that describe given maps.

math.AC↗

arXiv2017

Orientations of 1-Factorizations and the List Chromatic Index of Small Graphs

As starting point, we formulate a corollary to the Quantitative Combinatorial Nullstellensatz. This corollary does not require the consideration of any coefficients of polynomials, only evaluations of polynomial functions. In certain situations, our corollary is more directly applicable and more ready-to-go than the Combinatorial Nullstellensatz itself. It is also of interest from a numerical point of view. We use it to explain a well-known connection between the sign of 1-factorizations (edge colorings) and the List Edge Coloring Conjecture. For efficient calculations and a better understanding of the sign, we then introduce and characterize the sign of single 1-factors. We show that the product over all signs of all the 1-factors in a 1-factorization is the sign of that 1-factorization. Using this result in an algorithm, we attempt to prove the List Edge Coloring Conjecture for all graphs with up to 10 vertices. This leaves us with some exceptional cases that need to be attacked with other methods.

math.CO↗

arXiv2016

The Moments of Lévy's area using a sticky shuffle Hopf algebra

Lévy's stochastic area for planar Brownian motion is the difference of two iterated integrals of second rank against its component one-dimen\-sional Brownian motions. Such iterated integrals can be multiplied using the sticky shuffle product determined by the underlying Itô algebra of stochastic differentials. We use combinatorial enumerations that arise from the distributive law in the corresponding Hopf algebra structure to evaluate the moments of Lévy's area. These Lévy moments are well known to be given essentially by the Euler numbers. This has recently been confirmed in a novel combinatorial approach by Levin and Wildon. Our combinatorial calculations considerably simplify their approach.

math.PR↗

arXiv2016

Moments of quantum Lévy areas using sticky shuffle Hopf algebras

We study a family of quantum analogs of Lévy's stochastic area for planar Brownian motion depending on a variance parameter $σ\geq 1$ which deform to the classical Lévy area as $σ\rightarrow\infty$. They are defined as second rank iterated stochastic integrals against the components of planar Brownian motion, which are one-dimensional Brownian motions satisfying Heisnberg-type commutation relations. Such iterated integrals can be multiplied using the sticky shuffle product determined by the underlying Itô algebra of stochastic differentials. We use the corresponding Hopf algebra structure to evaluate the moments of the quantum Lévy areas and study how they deform to their classical values, which are well known to be given essentially by the Euler numbers, in the infinite variance limit.

math.PR↗

arXiv2016

The Tournament Scheduling Problem with Absences

We study time scheduling problems with allowed absences as a new kind of graph coloring problem. One may think of a sport tournament where each player (each team) is permitted a certain number $t$ of absences. We then examine how many rounds are needed to schedule the whole tournament in the worst case. This upper limit depends on $t$ and on the structure of the graph $G$ whose edges represent the games that have to be played, but also on whether or not the absences are announced before the tournament starts. Therefore, we actually have two upper limits for the number of required rounds. We have $χ^t(G)$ for pre-scheduling if all absences are pre-fixed, and we have $χ_{\textit{OL}}^t(G)$ for on-line scheduling if we have to stay flexible and deal with absences when they occur. We conjecture that $χ^t(G)=Δ(G)+2t$ and that $χ_{\textit{OL}}^t(G)=χ'(G)+2t.$ The first conjecture is stronger than the Total Coloring Conjecture while the second is weaker than the On-Line List Edge Coloring Conjecture. Our conjectures hold for all bipartite graphs. For complete graphs, we prove them partially. Lower and upper bounds to $χ^t(G)$ and $χ_{\textit{OL}}^t(G)$ for general multigraphs $G$ are established, too.

math.CO↗

arXiv2012

Quantitative Combinatorial Nullstellensatz

The main result of this paper is a coefficient formula that sharpens and generalizes Alon and Tarsi's Combinatorial Nullstellensatz, which provides some information about the polynomial map $P|_{\X_1\times...\times\X_n}$ when only incomplete information about the polynomial $P(X_1,...c,X_n)$ is given. In a very general working frame, the grid points $x\in\X_1\times\...b\times\X_n$ which do not vanish under an algebraic solution -- a certain describing polynomial $P(X_1,...c,X_n)$ -- correspond to the explicit solutions of a problem. As a consequence of the coefficient formula, we prove that the existence of an algebraic solution is equivalent to the existence of a nontrivial solution to a problem. By a problem, we mean everything that "owns" both, a set $§$, which may be called the \emph{set of solutions}; and a subset $\St\subseteq§$, the \emph{set of trivial solutions}. We give several examples of how to find algebraic solutions, and how to apply our coefficient formula. These examples are mainly from graph theory and combinatorial number theory, but we also prove several versions of Chevalley and Warning's Theorem, including a generalization of Olson's Theorem, as examples and useful corollaries. We obtain a permanent formula by applying our coefficient formula to the matrix polynomial, which is a generalization of the graph polynomial. This formula is an integrative generalization and sharpening of: 1. Ryser's permanent formula. 2. Alon's Permanent Lemma. 3. Alon and Tarsi's Theorem about orientations and colorings of graphs. Furthermore, in combination with the Vigneron-Ellingham-Goddyn property of planar (n)regular graphs, the formula contains as very special cases: 4. Scheim's formula for the number of edge (n)-colorings of such graphs. 5. Ellingham and Goddyn's partial answer to the list coloring conjecture.

math.CO↗

arXiv2009

Algebraic proof of Brooks' theorem

We give a proof of Brooks' theorem and its list coloring extension using the algebraic method of Alon and Tarsi; this also shows that the Brooks' theorem remains valid in a more general game coloring setting.

math.CO↗