Iskanje po katalogu digitalne knjižnice

Opis: A graph ▫$G$▫ is an efficient open domination graph if there exists a subset ▫$D$▫ of ▫$V(G)$▫ for which the open neighborhoods centered in vertices of ▫$D$▫ form a partition of ▫$V(G)$▫. We completely describe efficient open domination graphs among lexicographic, strong, and disjunctive products of graphs. For the Cartesian product we give a characterization when one factor is ▫$K_2$▫.
Ključne besede: graph theory, efficient open domination, graph products, total domination
Objavljeno v DKUM: 10.07.2017; Ogledov: 1379; Prenosov: 163
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Opis: The first commercial aquaponics companies are starting up in Europe. The main focus has been on solving technology issues and optimizing production. However, increasing attention is now being paid to certification and regulations linked to aquaponics, as well as the marketing of products and services. The paper presents the results of a study whose main aim was to estimate consumers’ knowledge about aquaponics and their acceptance of aquaponics products in different European regions. An on-line questionnaire was administered to the general public through the aquaponics network of Food and Agriculture COST (European Cooperation in Science and Technology) Action FA1305 “The EU Aquaponics Hub—Realising Sustainable Integrated Fish and Vegetable Production for the EU” in 16 European countries. The methodology includes univariate and multivariate statistical techniques. The results show that, on average, attitudes towards aquaponics were positive, showing no significant differences between those who already knew about aquaponics and those who only heard about it through the survey. More than 50% of respondents had never heard of aquaponics, whilst more than 70% had already heard of hydroponics. No more than 17% of respondents were willing to pay more for aquaponically produced products and no more than 40% more when compared to the price of products from conventional farming. The results confirm three different clusters of potential consumers of aquaponics products. They also suggest an urgent need for implementing integrated and holistic approaches involving all stakeholders in aquaponics, in order to define a marketing plan and efficient communication strategies. This COST action, other projects and public decision makers must invest in educating consumers about aquaponics through the organization of guided tours, thematic workshops and tastings of aquaponics products in order to raise their awareness about this new technology. It is absolutely urgent that public decision makers, in cooperation with aquaponics stakeholders, address the main institutional constraints, namely the introduction of aquaponics as an economic activity and the organic certification of aquaponics products.
Ključne besede: aquaponics, hydroponics, aquaponics products, consumers' acceptance, questionnaire, multivariate statistics, Europe
Objavljeno v DKUM: 22.06.2017; Ogledov: 1552; Prenosov: 382
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Opis: Kartezični svežnji so posplošitev krovnih grafov in kartezičnih grafovskih produktov. Naj bo ▫$G$▫ nek s povezavami ▫$k_G$▫-povezan graf in ▫${bar{mathcal{D}}_c(G)}$▫ največji premer podgrafov grafa ▫$G$▫ dobljenih z odstranitvijo $▫c < k_G$▫ povezav. Dokazano je, da je ▫${bar{mathcal{D}}_{a+b+1}(G)} le {bar{mathcal{D}}_a(F)} le {bar{mathcal{D}}_b(B)} + 1$▫, če je ▫$G$▫ grafovski sveženj z vlaknom ▫$F$▫ in bazo ▫$B$▫, ▫$a < k_F$▫, ▫$b < k_B▫$. Dokazano je tudi, da je povezanost s povezavami grafovskega svežnja ▫$G▫$ vsaj ▫$k_F + k_B$▫.
Ključne besede: matematika, teorija grafov, kartezični grafovski produkti, kartezični grafovski svežnji, povezavni okvarni premer, mathematics, graph theory, Cartesian graph products, Cartesian graph bundles, edge-fault diameter
Objavljeno v DKUM: 10.07.2015; Ogledov: 1483; Prenosov: 92
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Opis: V tem kratkem prispevku razširimo rezultate Fernándeza, Leightona in López-Presa o enoličnosti ▫$r$▫-tih korenov nepovezanih grafov glede na kartezični produkt na druge produkte in pokažemo, da lahko z njihovimi metodami izpeljemo nova pravila krajšanja.
Ključne besede: matematika, teorija grafov, produkti grafov, pravilo krajšanja, enoličnost korenov, mathematics, graph theory, graph products, cancellation property, uniqueness of roots
Objavljeno v DKUM: 10.07.2015; Ogledov: 1270; Prenosov: 90
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Opis: Razlikovalno število ▫$D(G)$▫ grafa je najmanjše celo število ▫$d$▫, za katero obstaja taka ▫$d$▫-označitev točk grafa ▫$G$▫, da je ne ohranja noben avtomorfizem grafa ▫$G$▫. Dokažemo, da je razlikovalno število kvadrata in višjih potenc povezanega grafa ▫$G ne K_2, K_3$▫, glede na kartezični produkt, vedno enako 2. Ta rezultat je močnejši od rezultatov Albertsona [Electron J Combin, 12 (2005), N17] za potence pra-grafov in tudi od rezultatov Klavžarja and Zhuja [European J. Combin, v tisku]. Bolj splošno, dokažemo tudi, da je ▫$(G Box H) = 2$▫, če sta ▫$G$▫ in ▫$H$▫ relativno tuja grafa in je ▫$|H| le |G| < 2^{|H|} - |H|$▫. Pod podobnimi pogoji veljajo sorodni rezultati tudi za potence grafov glede na krepki in direktni produkt grafov.
Ključne besede: matematika, teorija grafov, razlikovalno število, grafovski avtomorfizem, produkti grafov, mathematics, graph theory, distingushing number, graph automorphism, products of graphs
Objavljeno v DKUM: 10.07.2015; Ogledov: 1234; Prenosov: 97
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