W e prove that any graph with maximum degree n which can be obtained by removing exactly 2n -1 edges from the join K? -K, ,, is n-critical This generalizes special constructions of critical graphs by S Fiorini and H P Yap, and suggests a possible extension of another general construction due to Yap
Constructions of bipartite graphs from finite geometries
β Scribed by Keith E. Mellinger; Dhruv Mubayi
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 99 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0364-9024
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β¦ Synopsis
Abstract
We construct an incidence structure using certain points and lines in finite projective spaces. The structural properties of the associated bipartite incidence graphs are analyzed. These n Γ n bipartite graphs provide constructions of C~6~βfree graphs with Ξ©(n^4/3^ edges, C~10~βfree graphs with Ξ©(n^6/5^) edges, and Ξ(7,7,7)βfree graphs with Ξ©(n^8/7^) edges. Each of these bounds is sharp in order of magnitude. Β© 2005 Wiley Periodicals, Inc. J Graph Theory 49: 1β10, 2005
π SIMILAR VOLUMES
d 2,n 2 ) is a bipartite graphical sequence, if there is a bipartite graph G with degrees {D 1 , D 2 } (i.e., G has two independent vertex sets In other words, {D 1 , D 2 } is a bipartite graphical sequence if and only if there is an n 1 1 n 2 matrix of 0's and 1's having d 1j 1 1's in row j 1 and
In 1998 Mathon constructed algebraically a class of partial geometries pg(q -1, (q 2 -1)/2, (q -1)/2), where q is an even power of 3. The point graph of these partial geometries is the Hermitian graph constructed by Taylor. In this paper a geometric construction of Mathon's partial geometries is giv
We generalize the construction of F. R. Chung of graphs from finite fields and estimate their parameters with the help of a new bound of exponential sums due to G. I. Perel'muter and the author.