1311. Linear maps preserving numerical radius of tensor products of matricesAjda Fošner, Zejun Huang, Chi-Kwong Li, Nung-Sing Sze, 2013, izvirni znanstveni članek Opis: V članku so karakterizirane linearne preslikave na tenzorskem produktu kompleksnih matrik, ki ohranjajo numerični radij.
Ključne besede: matematika, teorija matrik, kompleksne matrike, linearni ohranjevalci, numerični rang, numerični radij, tenzorski produkt
Objavljeno v RUP: 15.10.2013; Ogledov: 7631; Prenosov: 108
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1315. Vertex-transitive expansions of (1, 3)-treesMarko Lovrečič Saražin, Dragan Marušič, 2010, objavljeni znanstveni prispevek na konferenci Opis: A nonidentity automorphism of a graph is said to be semiregular if all of its orbits are of the same length. Given a graph ▫$X$▫ with a semiregular automorphism ▫$\gamma$▫, the quotient of ▫$X$▫ relative to ▫$\gamma$▫ is the multigraph ▫$X/\gamma$▫ whose vertices are the orbits of ▫$\gamma$▫ and two vertices are adjacent by an edge with multiplicity ▫$r$▫ if every vertex of one orbit is adjacent to ▫$r$▫ vertices of the other orbit. We say that ▫$X$▫ is an expansion of ▫$X/\gamma$▫. In [J.D. Horton, I.Z. Bouwer, Symmetric ▫$Y$▫-graphs and ▫$H$▫-graphs, J. Combin. Theory Ser. B 53 (1991) 114-129], Hortonand Bouwer considered a restricted sort of expansions (which we will call :strong" in this paper) where every leaf of ▫$X/\gamma$▫ expands to a single cycle in ▫$X$▫. They determined all cubic arc-transitive strong expansions of simple ▫$(1,3)$▫-trees, that is, trees with all of their vertice shaving valency 1 or 3, thus extending the classical result of Frucht, Graver and Watkins (see [R. Frucht, J.E. Graver, M.E. Watkins, The groups of the generalized Petersen graphs, Proc. Cambridge Philos. Soc. 70 (1971) 211-218]) about arc-transitive strong expansions of ▫$K_2$▫ (also known as the generalized Petersen graphs). In this paper another step is taken further by considering the possible structure of cubic vertex-transitive expansions of general ▫$(1,3)$▫-multitrees (where vertices with double edges are also allowed); thus the restriction on every leaf to be expanded to a single cycle is dropped.
Ključne besede: graph, tree, cubic, vertex-transitive, arc-transitive, expansion
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1317. The saving and empowering young lives in Europe (SEYLE) randomized controlled trial (RCT)Vladimir Carli, Urša Mars Bitenc, Vita Poštuvan, 2013, izvirni znanstveni članek Ključne besede: SEYLE, mental health promotion, suicide prevention, promotion, well-being, adolescents, schools, RCT, intervention, ProfScreen, QPR, awareness
Objavljeno v RUP: 15.10.2013; Ogledov: 7495; Prenosov: 78
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