| Title: | On $k$-pairable graphs from trees (English) | 
| Author: | Che, Zhongyuan | 
| Language: | English | 
| Journal: | Czechoslovak Mathematical Journal | 
| ISSN: | 0011-4642 (print) | 
| ISSN: | 1572-9141 (online) | 
| Volume: | 57 | 
| Issue: | 1 | 
| Year: | 2007 | 
| Pages: | 377-386 | 
| Summary lang: | English | 
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| Category: | math | 
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| Summary: | The concept of the $k$-pairable graphs was introduced by Zhibo Chen (On $k$-pairable graphs, Discrete Mathematics  287 (2004), 11–15) as an extension of hypercubes and graphs with an antipodal isomorphism. In the same paper, Chen also introduced a new graph parameter  $p(G)$, called the pair length of a graph  $G$, as the maximum  $k$ such that $G$ is $k$-pairable and $p(G)=0$ if $G$  is not $k$-pairable for any positive integer  $k$. In this paper, we answer the two open questions raised by Chen in the case that the graphs involved are restricted to be trees. That is, we characterize the trees  $G$ with $p(G)=1$ and prove that $p(G \square H)=p(G)+p(H)$ when both $G$ and $H$  are trees. (English) | 
| Keyword: | $k$-pairable graph | 
| Keyword: | pair length | 
| Keyword: | Cartesian product | 
| Keyword: | $G$-layer | 
| Keyword: | tree | 
| MSC: | 05C05 | 
| MSC: | 05C60 | 
| MSC: | 05C75 | 
| MSC: | 68R10 | 
| idZBL: | Zbl 1174.05106 | 
| idMR: | MR2309971 | 
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| Date available: | 2009-09-24T11:46:19Z | 
| Last updated: | 2020-07-03 | 
| Stable URL: | http://hdl.handle.net/10338.dmlcz/128177 | 
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| Reference: | [1] Z.  Chen: On $k$-pairable graphs.Discrete Math. 287 (2004), 11–15. Zbl 1050.05026, MR 2094052, 10.1016/j.disc.2004.04.012 | 
| Reference: | [2] N.  Graham, R. C. Entringer, L. A.  Székely: New tricks for old trees: maps and the pigeonhole principle.Amer. Math. Monthly 101 (1994), 664–667. MR 1289277, 10.2307/2974696 | 
| Reference: | [3] W.  Imrich, S.  Klavžar: Product Graphs: Structure and Recognition. Wiley-Interscience Series in Discrete Mathematics and Optimization.Wiley, Chichester, 2000. MR 1788124 | 
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