منابع مشابه
Out-branchings with Extremal Number of Leaves
An out-tree T in a digraph D is subgraph of D which is an orientation of a tree that has only one vertex of in-degree 0 (root). A vertex of T is a leaf if it has out-degree 0. A spanning out-tree is called an out-branching. We’ll overview some recent algorithmic and theoretical results on out-branchings with minimum and maximum number of leaves.
متن کاملSpanning Trees with a Bounded Number of Leaves
In 1998, H. Broersma and H. Tuinstra proved that: Given a connected graph G with n ≥ 3 vertices, if d(u) + d(v) ≥ n − k + 1 for all non-adjacent vertices u and v of G (k ≥ 1), then G has a spanning tree with at most k leaves. In this paper, we generalize this result by using implicit degree sum condition of t (2 ≤ t ≤ k) independent vertices and we prove what follows: Let G be a connected graph...
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We show that for any two values α, β ∈ (0, 1) for which α+β > 1 then there exists a value N so that for all n ≥ N , and any binary phylogenetic tree T on n leaves there exists a set of at most n characters that capture T , and for which each character has at most n states. Here ‘capture’ means that T is the only phylogenetic tree that is compatible with the characters. Our short proof of this c...
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wall carbohydrates, and organic acids. The hydroxycinnamic acid amides with tyramine and octopamine are also common types of conjugates.2) The formation of the amides serves a defensive purpose in solanaceous plants such as potato,3・4) tobacco5) and tomato.6) Various forms of stress, including physical injury, infection with pathogens and elicitor-treatments, induce the accumulation of hydroxyc...
متن کاملMercury removal from aqueous solutions by palm leaves adsorbent
Mercury is a carcinogenic and teratogenic compound that tends to accumulate in water solutions. In this research, the removal of mercury from an aqueous solution was evaluated by using palm leaves. Experiments were performed to study the adsorption efficiency, the effect of the adsorbent amount, the balance time, the adsorbate concentration, and the pH on mercury removal. The experimental appar...
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ژورنال
عنوان ژورنال: Nature
سال: 2003
ISSN: 0028-0836,1476-4687
DOI: 10.1038/426237a