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2. An identity between the determinant and the permanent of Hessenberg-type matrices
- Creator:
- Da Fonseca, Carlos Martins
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- determinant, permanent, Hessenberg matrices;, graphs, and trees
- Language:
- English
- Description:
- In this short note we provide an extension of the notion of Hessenberg matrix and observe an identity between the determinant and the permanent of such matrices. The celebrated identity due to Gibson involving Hessenberg matrices is consequently generalized.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
3. Anthocyanins function as a light attenuator to compensate for insufficient photoprotection mediated by nonphotochemical quenching in young leaves of Acmena acuminatissima in winter
- Creator:
- Zhu, H., Zhang, T.-J., Zheng, J., Huang, X.-D., Yu, Z.-C., Peng, C.-L., and Chow, W. S.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- stromy, pigmenty, roční období, ochrana před ultrafialovým zářením, trees, pigments, seasons, photoprotection, chlorophyll fluorescence, evergreen tree, gas exchange, 2, and 581
- Language:
- Multiple languages
- Description:
- Anthocyanins and nonphotochemical quenching (NPQ) are two important tools that provide photoprotection in plant leaves. In order to understand how plants use these tools for acclimation to changing seasonal conditions, we investigated pigments, antioxidative capacity, and photosynthesis in leaves of an evergreen tree (Acmena acuminatissima) in two contrasting seasons. Young leaves of A. acuminatissima appeared in distinct colors, being light green in summer and red in winter due to the presence of anthocyanins. In the winter young leaves, anthocyanins contributed less than 2% to the antioxidant pool. In the summer, young leaves had higher NPQ than that of mature leaves, but in the winter, they did not derive any NPQ-related advantage over mature leaves. These results suggest that the accumulation of anthocyanins in young leaves in the winter may compensate for the insufficient photoprotection afforded by NPQ and that anthocyanins function as a light attenuator to protect the photochemical apparatus against excess light., H. Zhu, T.-J. Zhang, J. Zheng, X.-D. Huang, Z.-C. Yu, C.-L. Peng, W. S. Chow., and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4. Arbology: trees and pushdown automata
- Creator:
- Melichar, Bořivoj, Janoušek, Jan, and Flouri, Tomáš
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- trees, pushdown automata, tree pattern matching, indexing trees, and arbology
- Language:
- English
- Description:
- We present a unified and systematic approach to basic principles of Arbology, a new algorithmic discipline focusing on algorithms on trees. Stringology, a highly developed algorithmic discipline in the area of string processing, can use finite automata as its basic model of computation. For various kinds of linear notations of ranked and unranked ordered trees it holds that subtrees of a tree in a linear notation are substrings of the tree in the linear notation. Arbology uses pushdown automata reading such linear notations of trees as its basic model of computation. Basic principles known from stringology are used for the construction of particular arbology algorithms, in which the underlying tree structure is processed with the use of the pushdown store. Arbology results are shown for the basic problems subtree matching and tree indexing for ranked and unranked ordered trees.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
5. Classifying trees with edge-deleted central appendage number 2
- Creator:
- Stalder, Shubhangi, Eroh, Linda, Koker, John, Moghadam, Hosien S., and Winters, Steven J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- graphs, trees, and central appendage number
- Language:
- English
- Description:
- The eccentricity of a vertex v of a connected graph G is the distance from v to a vertex farthest from v in G. The center of G is the subgraph of G induced by the vertices having minimum eccentricity. For a vertex v in a 2-edge-connected graph G, the edge-deleted eccentricity of v is defined to be the maximum eccentricity of v in G − e over all edges e of G. The edge-deleted center of G is the subgraph induced by those vertices of G having minimum edge-deleted eccentricity. The edge-deleted central appendage number of a graph G is the minimum difference |V (H)| − |V (G)| over all graphs H where the edgedeleted center of H is isomorphic to G. In this paper, we determine the edge-deleted central appendage number of all trees.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
6. Constructions for type I trees with nonisomorphic Perron branches
- Creator:
- Kirkland, Steve
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- math, trees, and Perron branches
- Language:
- English
- Description:
- A tree is classified as being type I provided that there are two or more Perron branches at its characteristic vertex. The question arises as to how one might construct such a tree in which the Perron branches at the characteristic vertex are not isomorphic. Motivated by an example of Grone and Merris, we produce a large class of such trees, and show how to construct others from them. We also investigate some of the properties of a subclass of these trees. Throughout, we exploit connections between characteristic vertices, algebraic connectivity, and Perron values of certain positive matrices associated with the tree.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
7. Les a strom ve starověké Číně
- Creator:
- Lukáš Zádrapa
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Dějiny Asie. Orient, lesy, stromy, kultura, starověk, forests, trees, culture, antiquity, Čína, China, 8, and 94(5)
- Language:
- Czech
- Description:
- The article traces the role and image of the wood and the tree in the culture of Ancient China as emerging from the transmitted literature of the Warring States period. Although this topic has already been touched upon in some previous studies, such as Mark Elvin's The Retreat of the Elephants, no comprehensive description based on at least nearly exhaustive systematization of respective data available to us in primary sources has been presented yet, especially for trees. In this paper, virtually all recorded modes of approaching the phenomena by the learned men of the Warring States are summarized and supplied with extensive reference to ancient texts. Apart from other issues, it clearly demonstrates that the skeptical stance to ancient Chinese love for nature and to the ecological ethos of traditional Chinese culture is highly justified., Lukáš Zádrapa., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
8. Nezneužívejme broukoviště proti broukům!
- Creator:
- Boukal, Milan, Lukáš Čížek, Ondřej Konvička, Dedek, Pavel, Jiří Řehounek, and Martin Škorpík
- Format:
- bez média and svazek
- Type:
- article, text, články, journal articles, model:article, and TEXT
- Subject:
- Biologické vědy, biologie, brouci, stromy, kácení dřevin, mrtvé dřevo, ochrana živočichů, deklarace, beetles, biology, trees, tree felling, dead wood, animal conservation, declarations, Česko, Czechia, broukoviště, loggery, 2, and 57/59
- Language:
- Czech
- Description:
- Milan Boukal, Lukáš Čížek, Ondřej Konvička, Pavel Dedek, Jiří Řehounek, Martin Škorpík.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
9. On super vertex-graceful unicyclic graphs
- Creator:
- Lee, Sin-Min, Leung, Elo, and Ng, Ho Kuen
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- graceful, edge-graceful, super edge-graceful, super vertex-graceful, amalgamation, trees, and unicyclic graphs
- Language:
- English
- Description:
- A graph $G$ with $p$ vertices and $q$ edges, vertex set $V(G)$ and edge set $E(G)$, is said to be super vertex-graceful (in short SVG), if there exists a function pair $(f, f^+)$ where $f$ is a bijection from $V(G)$ onto $P$, $f^+$ is a bijection from $E(G)$ onto $Q$, $f^+((u, v)) = f(u) + f(v)$ for any $(u, v) \in E(G)$, $$ Q = \begin{cases} \{\pm 1,\dots , \pm \frac 12q\},&\text {if $q$ is even,}\\ \{0, \pm 1, \dots , \pm \frac 12(q-1)\},&\text {if $q$ is odd,} \end{cases} $$ and $$ P = \begin{cases} \{\pm 1,\dots , \pm \frac 12p\},&\text {if $p$ is even,}\\ \{0, \pm 1, \dots , \pm \frac 12(p-1)\},&\text {if $p$ is odd.} \end{cases} $$ \endgraf We determine here families of unicyclic graphs that are super vertex-graceful.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
10. Ordering the non-starlike trees with large reverse Wiener indices
- Creator:
- Li, Shuxian and Zhou, Bo
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- distance, diameter, Wiener index, reverse Wiener index, trees, starlike trees;, and caterpillars
- Language:
- English
- Description:
- The reverse Wiener index of a connected graph $G$ is defined as \[ \Lambda (G)=\frac {1}{2}n(n-1)d-W(G), \] where $n$ is the number of vertices, $d$ is the diameter, and $W(G)$ is the Wiener index (the sum of distances between all unordered pairs of vertices) of $G$. We determine the $n$-vertex non-starlike trees with the first four largest reverse Wiener indices for $n\ge 8$, and the $n$-vertex non-starlike non-caterpillar trees with the first four largest reverse Wiener indices for $n\ge 10$.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public