# FUN-Veranstaltungen

FoFö-Stammtisch, 23. November 2017, 14 Uhr siehe Info-Veranstaltungen

# Kontakt

Abteilung Forschungsunterstützung (FUN):
forschen@jku.at

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# Forschungseinheiten

Vortrag auf einer Tagung (nicht referiert)

## A remark on the composition of polynomial functions over algebraically closed fields

### Details

Zusammenfassung: In 1969, M.\ D.\ Fried and R.\ E.\ MacRae proved that for univariate polynomials $p,q, f, g \in \mathbb{K}[t]$ ($\mathbb{K}$ a field) with $p,q$ nonconstant, $p(x)-q(y)$ divides $f(x)-g(y)$ in $\mathbb{K}[x,y]$ if and only if there is $h \in \mathbb{K}[t]$ such that $f=h(p(t))$ and $g=h(q(t))$. In 1995, F.\ Binder and the author provided short algebraic proofs of this theorem, and J.\ Schicho gave a proof from the viewpoint of category theory, thereby providing several generalizations to multivariate polynomials. In this talk, we give an algebraic proof of one of these generalizations. % % The theorem by Fried and MacRae yields a way to prove the following fact for nonconstant functions $f,g$ from $\mathbb{C}$ to $\mathbb{C}$: if both the composition $f \circ g$ and $g$ are polynomial functions, then $f$ has to be a polynomial function as well. We give an algebraic proof of this fact and present a generalization to multivariate polynomials over algebraically closed fields. % As an application, one obtains a generalization of a result by L.\ Carlitz from 1963 that describes those univariate polynomials over finite fields that induce injective functions on all of their extensions. Part of this research is joint work with S.\ Steinerberger (Bonn, Germany).

Tagungstitel: AAA81 - 81. Arbeitstagung Allgemeine Algebra
Vortragsdatum: 05.02.2011
Web: http://dmg.tuwien.ac.at/aaa81/ (Konferenz-Homepage)
Land: Österreich
Ort: Universitaet Salzburg

### Beteiligte

ReferentInnen: Assoz.Univprof. DI Dr. Erhard Aichinger

Forschungseinheiten der JKU:

Wissenschaftszweige: 1102 Algebra | 1107 Geometrie | 1119 Zahlentheorie | 1131 Computer Algebra