The aspherical Cavicchioli-Hegenbarth-Repovš generalized Fibonacci groups

The Cavicchioli–Hegenbarth–Repovš generalized Fibonacci groups are defined by the presentations Gn (m, k) = 〈x 1, … , xn | xixi+m = xi+k (1 ⩽ i ⩽ n)〉. These cyclically presented groups generalize Conway's Fibonacci groups and the Sieradski groups. Building on a theorem of Bardakov and Vesnin we classify the aspherical presentations Gn (m, k). We determine when Gn (m, k) has infinite abelianization and provide sufficient conditions for Gn (m, k) to be perfect. We conjecture that these are also necessary conditions. Combined with our asphericity theorem, a proof of this conjecture would imply a classification of the finite Cavicchioli–Hegenbarth–Repovš groups

Radiation reaction and quantum damped harmonic oscillator

By taking a Klein-Gordon field as the environment of an harmonic oscillator and using a new method for dealing with quantum dissipative systems (minimal coupling method), the quantum dynamics and radiation reaction for a quantum damped harmonic oscillator investigated. Applying perturbation method, some transition probabilities indicating the way energy flows between oscillator, reservoir and quantum vacuum, obtainedComment: 12 pages. Accepted for publication in Mod. Phys. Lett.

Correlation of bio- and magnetostratigraphy of Badenian sequences from western and northern Hungary

Lithological, magnetostratigraphic and paleontological (nannoplankton, foraminifers, molluscs) studies were carried out on the Badenian successions of boreholes Sopron-89, Nagylozs-1 and Sata-75 in Hungary. The correlations with the ATNTS2004 scale show that the Badenian sedimentation began during Chron C5Br thus the earliest Badenian deposits are missing in the sections. The first occurrence of Orbulina suturalis Bronnimann has been observed in Subchron C5Bn.1r, at 14.9 Ma. Although it is older than the interpolated age of 14.74 Ma in Chron C5ADr in the ATNTS2004, it is consistent with the age of 15.1 Ma obtained from recent calibration of planktonic foraminiferal bioevents. The base of the Bulimina-Bolivina Zone has been determined at 13.7 Ma in Chron C5ABr, and the Badenian/Sarmatian boundary is recorded within Chron C5AAn, at 13.15 Ma

Technológiai Előretekintési Program

Az Országos Mûszaki Fejlesztési Bizottság döntése alapján 1998-ban átfogó elemzés kezdôdött Technoló- giai Elôretekintési Program (TEP) néven. A program célja, hogy a piaci és technológiai lehetôségek feltá- rásával hozzájáruljon a hosszú távú versenyképesség növeléséhez és ezen keresztül az életminôség javításá- hoz. A TEP a gazdasági, társadalmi folyamatok, a tudo- mány és technika eredményeinek elemzésével megje- löli azon kulcskérdéseket, döntési pontokat, amelyek meghatározzák az egyes szakmai területek illetve az ország jövôjét a következô 15-25 évben. Az Irányító Testület és a munkacsoportok elemezték a jelenlegi helyzetet, eltérô jövôképeket vázoltak fel, és a legked- vezôbbnek ítélt – de a mai feltételek mellett, tudatos, összehangolt erôfeszítések nélkül nem feltétlenül a leg- valószínûbb – jövôkép megvalósítását célzó ajánlásokat fogalmaztak meg. A legkedvezôbb jövôképbôl leve- zetett ajánlások tehát mindazoknak szólnak, akik köz- vetlenül vagy közvetve hatással lehetnek az egyes szakterületek vagy a magyar társadalom és gazdaság egészének jövôjére

All simple groups with order from 1 million to 5 million are efficient

There is much interest in finding short presentations for the finite simple groups. Indeed it has been suggested that all these groups are efficient in a technical sense. In previous papers we produced nice efficient presentations for all except one of the simple groups with order less than one million. Here we show that all simple groups with order between 1 million and 5 million are efficient by giving efficient presentations for all of them. Apart from some linear groups these results are all new. We also show that some covering groups and some larger simple groups are efficient We make substantial use of systems for computational group theory and, in particular, of computer implementations of coset enumeration to find and verify our presentations