Homomorphisms of Trees into a Path
نویسندگان
چکیده
Let hom(G,H) denote the number of homomorphisms from a graph G to a graph H. In this paper we study the number of homomorphisms of trees into a path, and prove that hom(Pm, Pn) ≤ hom(Tm, Pn) ≤ hom(Sm, Pn), where Tm is any tree on m vertices, and Pm and Sm denote the path and star on m vertices, respectively. This completes the study of extremal problems concerning the number of homomorphisms between trees started in the paper Graph Homomorphisms Between Trees [Electron. J. Combin., 21 (2014), 4.9] written by the authors of the current paper.
منابع مشابه
Graph Homomorphisms between Trees
In this paper we study several problems concerning the number of homomorphisms of trees. We begin with an algorithm for the number of homomorphisms from a tree to any graph. By using this algorithm and some transformations on trees, we study various extremal problems about the number of homomorphisms of trees. These applications include a far reaching generalization and a dual of Bollobás and T...
متن کاملStructured Parallel Computation in Structured Documents
Document archives contain large amounts of data to which sophisticated queries are applied. The size of archives and the complexity of evaluating queries makes the use of parallelism attractive. The use of semantically-based markup such as SGML makes it possible to represent documents and document archives as data types. We present a theory of trees and tree homomorphisms, modelling structured ...
متن کاملA Certain Class of Character Module Homomorphisms on Normed Algebras
For two normed algebras $A$ and $B$ with the character space $bigtriangleup(B)neq emptyset$ and a left $B-$module $X,$ a certain class of bounded linear maps from $A$ into $X$ is introduced. We set $CMH_B(A, X)$ as the set of all non-zero $B-$character module homomorphisms from $A$ into $X$. In the case where $bigtriangleup(B)=lbrace varphirbrace$ then $CMH_B(A, X)bigcup lbrace 0rbrace$ is...
متن کاملMedian Structures on Asymptotic Cones and Homomorphisms into Mapping Class Groups
We prove that every asymptotic cone of a mapping class group has a bi-Lipschitz equivariant embedding into a product of real trees, with image a median subspace. We deduce several applications of this, one of which is that a group with Kazhdan’s property (T) can only have finitely many pairwise non-conjugate homomorphisms into a mapping class group.
متن کاملAutomatic continuity of surjective $n$-homomorphisms on Banach algebras
In this paper, we show that every surjective $n$-homomorphism ($n$-anti-homomorphism) from a Banach algebra $A$ into a semisimple Banach algebra $B$ is continuous.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- SIAM J. Discrete Math.
دوره 29 شماره
صفحات -
تاریخ انتشار 2015