Discussiones Mathematicae Graph Theory 27(3) (2007) 389-400
doi: 10.7151/dmgt.1369

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Hortensia Galeana-Sánchez

Instituto de Matemáticas
Universidad Nacional Autónoma de México
Ciudad Universitaria, México, D.F. 04510, México

Luis Alberto Jiménez Ramírez

Facultad de Ciencias
Universidad Nacional Autónoma de México
Ciudad Universitaria, México, D.F. 04510, México


In this paper, we introduce the concept of monochromatic kernel-perfect digraph, and we prove the following two results:

(1) If D is a digraph without monochromatic directed cycles, then D and each αv,v ∈ V(D) are monochromatic kernel-perfect digraphs if and only if the composition over D of (αv)v ∈ V(D) is a monochromatic kernel-perfect digraph.

(2) D is a monochromatic kernel-perfect digraph if and only if for any B ⊆ V(D), the duplication of D over B, DB, is a monochromatic kernel-perfect digraph.

Keywords: kernel, kernel by monochromatic paths, composition, duplication.

2000 Mathematics Subject Classification: 05C20.


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Received 17 January 2006
Revised 11 June 2007
Accepted 11 June 2007