3 research outputs found
Note on a Conjecture of Wegner
The optimal packings of n unit discs in the plane are known for those natural
numbers n, which satisfy certain number theoretic conditions. Their geometric
realizations are the extremal Groemer packings (or Wegner packings). But an
extremal Groemer packing of n unit discs does not exist for all natural numbers
n and in this case, the number n is called exceptional. We are interested in
number theoretic characterizations of the exceptional numbers. A counterexample
is given to a conjecture of Wegner concerning such a characterization. We
further give a characterization of the exceptional numbers, whose shape is
closely related to that of Wegner's conjecture.Comment: 5 pages; Contributions to Algebra and Geometry, Vol.52 No1 April 201
PozitĂv definit fĂĽggvĂ©nyek, extremális problĂ©mák Ă©s alkalmazásaik = Positive definite functions, extremal problems and applications
EredmĂ©nyeink többsĂ©ge nemzetközi folyĂłiratokban jelent meg/van elfogadva, konferencia-kiadványokkal egyĂĽtt mintegy fĂ©lszáz tudományos közlemĂ©nyt publikáltunk. EredmĂ©nyeinkrĹ‘l kb. százhĂşsz nemzetközi konferencia- illetve szemináriumi elĹ‘adást tartottunk. A munkatervben szereplĹ‘ tĂ©mák, feladatok tĂşlnyomĂł többsĂ©gĂ©ben a tervezettnĂ©l tovább sikerĂĽlt eljutni, ezen felĂĽl számos elĹ‘re nem látott illetve tervezett kĂ©rdĂ©sben Ă©rtĂĽnk el Ă©rdemleges kutatási eredmĂ©nyeket. A Turán-fĂ©le extremális problĂ©mában több becslĂ©st dolgoztunk ki, amelyek az alaphalmaz struktĂşrális tulajdonságait használják Az egyenletes aszimptotikus felsĹ‘ sűrűsĂ©g fogalmának Ăşj Ă©rtelmezĂ©sĂ©t adtuk lokálisan kompakt Abel csoportokra, ennek rĂ©vĂ©n egyes eredmĂ©nyeket ki tudtunk terjeszteni. A hiperbolikus tĂ©rbeli gömbelhelyezĂ©sek teljes családját magában foglalĂł sűrűsĂ©gfogalmat adtunk, igazolva, hogy a sűrűsĂ©gfogalom a periĂłdikus esetkiterjesztĂ©se. Megoldottuk Molnár JĂłzsef egy negyven Ă©ves sejtĂ©sĂ©t is. T. Tao 2004-ben megcáfolta Fuglede sejtĂ©sĂ©t arrĂłl, hogy euklideszi tĂ©rben a parkettázĂł halmazok spektrálisak Ă©s viszont. A Fuglede sejtĂ©s Tao által nyitva hagyott másik irányát is sikerĂĽlt megcáfolni. Az egysĂ©gkörön Ă©s a felsĹ‘ fĂ©lsĂkban szinguláris peremfĂĽggvĂ©nyek mellett vizsgáltuk a Dirichlet problĂ©mát. Itt a Poisson operátor Ă©rtelmezĂ©se, ortogonális rendszer minimális teljes ritkĂtása, (vĂ©gtelen) interpoláciĂłs feladat megoldása Ă©s Lp-beli Abel szummáciĂłs eljárások rĂ©vĂ©n Ă©rtĂĽnk el eredmĂ©nyeket. | Most of our results were published/accepted in international journals: alltogether with conference proceedings publications we produced cca. half of a hundred publications. About these we delivered approximately 120 lectures at conferences and seminars all over the world. In most of the the tasks listed in our project plan we proceeded further than planned, and we achieved reserch results in numerous other problems, too. We obtained estimates in the Turán extremal problem using structural properties of the set. We extended the notion of uniform upper assymptotic density to locally compact Abelian groups, and thus extended results on the Turán extremal problem, too. Also the Landau- and the pointwise Turán extremal problem were explored. We defined density for sphere packing of hyperbolic space, showing that in the periodic case our notion becomes the expected density. A 40 years old conjecture of J. Molnár was also solved. T. Tao gave counterexample to the Fuglede spectral set conjecture in 2004. We disproved the other direction of the conjecture, left open by Tao, and obtained several further results, too. On the unit disk and also on the upper halfplane we copnsidered the Dirichlet problem with singular boundary functions. Here the minimal and complete subset of the weighted orthonormal system, construction of the Poisson operator, an infinite interpolation problem and Lp Abel summability were dealt with
Note on an inequality of Wegner
G. Wegner [12] gave a geometric characterization of all so–called Groemer packing of n ≥ 2 unit discs in E 2 that are densest packings of n unit discs with respect to the convex hull of the discs. In this paper we provide a number theoretic characterization of all n satisfying that such a “Wegner packing ” of n unit discs exists, and show that the proportion of these n is 23 24 among all natural numbers. Acknowledgement: We are grateful to J.C. Lagarias for helpful discussions, and to an unknown referee whose remarks considerably improved the paper