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Your search keyword '"Teo, K.L."' showing total 13 results
Start Over Author "Teo, K.L." Journal discrete mathematics
13 results on '"Teo, K.L."'

5. Chromatic equivalence classes of certain generalized polygon trees

Author

Peng, Yee-Hock, Little, C.H.C., Teo, K.L., and Wang, H.

Subjects
Mathematics::Combinatorics, Computer Science::Discrete Mathematics, Discrete Mathematics and Combinatorics, Theoretical Computer Science
Abstract

Let P(G) denote the chromatic polynomial of a graph G. Two graphs G and H are chromatically equivalent, written G ∼ H, if P(G) = P(H). Let g denote the family of all generalized polygon trees with three interior regions. Xu (1994) showed that g is a union of chromatic equivalence classes under the equivalence relation ‘∼’. In this paper, we determine infinitely many chromatic equivalence classes in g under ‘∼’. As a byproduct, we obtain a family of chromatically unique graphs established by Peng (1995).

Published
1997

6. Preface

Author

Chen, C.C., Chia, G.L., Koh, K.M., Li, N.Z., and Teo, K.L.

Subjects
Discrete Mathematics and Combinatorics, Theoretical Computer Science
Published
1997
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11. <atl>Non-chordal graphs having integral-root chromatic polynomials II

Author

Dong, F.M., Teo, K.L., Koh, K.M., and Hendy, M.D.

Subjects
*GRAPHIC methods, *POLYNOMIALS
Abstract

It is known that the chromatic polynomial of any chordal graph has only integer roots. However, there also exist non-chordal graphs whose chromatic polynomials have only integer roots. Dmitriev asked in 1980 if for any integer p&ges;4, there exists a graph with chordless cycles of length p whose chromatic polynomial has only integer roots. This question has been given positive answers by Dong and Koh for p=4 and p=5. In this paper, we construct a family of graphs in which all chordless cycles are of length p for any integer p&ges;4. It is shown that the chromatic polynomial of such a graph has only integer roots iff a polynomial of degree p−1 has only integer roots. By this result, this paper extends Dong and Koh''s result for p=5 and answer the question affirmatively for p=6 and 7. [Copyright &y& Elsevier]

Published
2002
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13. Chromatic classes of 2-connected (n, n+ 3)-graphs with at least two triangles

Author

Koh, K.M. and Teo, K.L.

Abstract

Let P(G) denote the chromatic polynomial of a graph G. Two graphs Gand Hare chromatically equivalent, written G∼ H, if P(G) = P(H). A graph Gis chromatically unique if G≅ Hfor any graph Hsuch that H∼ G. Let Hdenote the class of 2-connected graphs with nvertices and n+ 3 edges which contain at least two triangles. It follows that if G ϵ Hand H∼ G, then H ϵ H. In this paper, we determine all equivalence classes in Hunder the equivalence relation ∼ and characterize the structure of the graphs in each class. As a by-product of these, we obtain various new families of chromatically equivalent graphs and chromatically unique graphs.

Published
1994
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