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Title:Classification of convex polyhedra by their rotational orbit Euler characteristic
Authors:ID Kovič, Jurij (Author)
Files:.pdf RAZ_Kovic_Jurij_i2017.pdf (272,96 KB)
MD5: 34C55610C9518FB2AA931FEDFA9E96B9
 
Language:English
Work type:Unknown
Typology:1.01 - Original Scientific Article
Organization:ZUP - University of Primorska Press
Abstract:Let ▫$\mathcal P$▫ be a polyhedron whose boundary consists of flat polygonal faces on some compact surface ▫$S(\mathcal P)$▫ (not necessarily homeomorphic to the sphere ▫$S^{2}$)▫. Let ▫$vo_{R}(\mathcal P), eo_{R}(\mathcal P)$▫, ▫$ fo_{R}(\mathcal P)$▫ be the numbers of rotational orbits of vertices, edges and faces, respectively, determined by the group ▫$G = G_{R}(P)$▫ of all the rotations of the Euclidean space ▫$E^{3}$▫ preserving ▫$\mathcal P$▫. We define the ''rotational orbit Euler characteristic'' of ▫$\mathcal P$▫ as the number ▫$Eo_{R}(\mathcal P) = vo_{R}(\mathcal P) - eo_{R}(\mathcal P) + fo_{R}(\mathcal P)$▫. Using the Burnside lemma we obtain the lower and the upper bound for ▫$Eo_{R}(\mathcal P)$▫ in terms of the genus of the surface ▫$S(P)$▫. We prove that ▫$Eo_{R} \in \lbrace 2,1,0,-1\rbrace $▫ for any convex polyhedron ▫$\mathcal P$▫. In the non-convex case ▫$Eo_{R}$▫ may be arbitrarily large or small.
Keywords:polyhedron, rotational orbit, Euler characteristic
Year of publishing:2017
Number of pages:str. 23-30
Numbering:Vol. 13, no. 1
PID:20.500.12556/RUP-17627 This link opens in a new window
UDC:514.113.5:519.1
ISSN on article:1855-3966
COBISS.SI-ID:17897561 This link opens in a new window
Publication date in RUP:02.01.2022
Views:1145
Downloads:19
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Record is a part of a journal

Title:Ars mathematica contemporanea
Publisher:Društvo matematikov, fizikov in astronomov, Društvo matematikov, fizikov in astronomov, Univerza na Primorskem, Fakulteta za matematiko, naravoslovje in informacijske tehnologije
ISSN:1855-3966
COBISS.SI-ID:239049984 This link opens in a new window

Secondary language

Language:Slovenian
Title:Klasifikacija konveksnih poliedrov glede na njihovo Eulerjevo karakteristiko rotacijskih orbit
Abstract:Naj bo ▫$\mathcal P$▫ polieder, katerega površje sestoji iz ploskih poligonskih lic na neki kompaktni ploskvi ▫$S(\mathcal P)$▫ (ne nujno homeomorfni sferi ▫$S^{2}$)▫. Naj bodo ▫$vo_{R}(\mathcal P), eo_{R}(\mathcal P)$▫, ▫$ fo_{R}(\mathcal P)$▫ ševila rotacijskih orbit vozlišč, povezav in lic, določena z grupo ▫$G = G_{R}(P)$▫ vseh takšnih rotacij evklidskega prostora ▫$E^{3}$▫, ki ohranjajo polieder ▫$\mathcal P$▫. Definiramo ''Eulerjevo karakteristiko rotacijskih orbit'' poliedra ▫$\mathcal P$▫ kot število ▫$Eo_{R}(\mathcal P) = vo_{R}(\mathcal P) - eo_{R}(\mathcal P) + fo_{R}(\mathcal P)$▫. S pomočjo Burnsidove leme dobimo spodnjo in zgornjo mejo za ▫$Eo_{R}(\mathcal P)$▫, ki ju izrazimo kot funkcijo reda ploskve ▫$S(P)$▫. Dokažemo, da je ▫$Eo_{R} \in \lbrace 2,1,0,-1\rbrace $▫ za vsak konveksen polieder ▫$\mathcal P$▫. V nekonveksnem primeru je ▫$Eo_{R}$▫ lahko poljubno velik ali majhen.
Keywords:polieder, rotacijska orbita, Eulerjeva karakteristika


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