کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4624542 1631619 2016 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Families of multiweights and pseudostars
ترجمه فارسی عنوان
خانواده هایی از چند وزن و شبه جزیره
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه ریاضیات ریاضیات کاربردی
چکیده انگلیسی

Let T=(T,w)T=(T,w) be a weighted finite tree with leaves 1,…,n1,…,n. For any I:={i1,…,ik}⊂{1,…,n}I:={i1,…,ik}⊂{1,…,n}, let DI(T)DI(T) be the weight of the minimal subtree of T   connecting i1,…,iki1,…,ik; the DI(T)DI(T) are called k  -weights of TT. Given a family of real numbers parametrized by the k  -subsets of {1,…,n}{1,…,n}, {DI}I∈({1,…,n}k), we say that a weighted tree T=(T,w)T=(T,w) with leaves 1,…,n1,…,n realizes the family if DI(T)=DIDI(T)=DI for any I.In [14] Pachter and Speyer proved that, if 3≤k≤(n+1)/23≤k≤(n+1)/2 and {DI}I∈({1,…,n}k) is a family of positive real numbers, then there exists at most one positive-weighted essential tree TT with leaves 1,…,n1,…,n that realizes the family (where “essential” means that there are no vertices of degree 2). We say that a tree P   is a pseudostar of kind (n,k)(n,k) if the cardinality of the leaf set is n and any edge of P divides the leaf set into two sets such that at least one of them has cardinality ≥k  . Here we show that, if 3≤k≤n−13≤k≤n−1 and {DI}I∈({1,…,n}k) is a family of real numbers realized by some weighted tree, then there is exactly one weighted essential pseudostar P=(P,w)P=(P,w) of kind (n,k)(n,k) with leaves 1,…,n1,…,n and without internal edges of weight 0, that realizes the family; moreover we describe how any other weighted tree realizing the family can be obtained from PP. Finally we examine the range of the total weight of the weighted trees realizing a fixed family.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Advances in Applied Mathematics - Volume 77, June 2016, Pages 86–100
نویسندگان
, ,