# On some variations of extremal graph problems

• Volume: 17, Issue: 1, page 67-76
• ISSN: 2083-5892

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## Abstract

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A set P of graphs is termed hereditary property if and only if it contains all subgraphs of any graph G belonging to P. A graph is said to be maximal with respect to a hereditary property P (shortly P-maximal) whenever it belongs to P and none of its proper supergraphs of the same order has the property P. A graph is P-extremal if it has a the maximum number of edges among all P-maximal graphs of given order. The number of its edges is denoted by ex(n, P). If the number of edges of a P-maximal graph is minimum, then the graph is called P-saturated and its number of edges is denoted by sat(n, P). In this paper, we consider two famous problems of extremal graph theory. We shall translate them into the language of P-maximal graphs and utilize the properties of the lattice of all hereditary properties in order to establish some general bounds and particular results. Particularly, we shall investigate the behaviour of sat(n,P) and ex(n,P) in some interesting intervals of the mentioned lattice.

## How to cite

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Gabriel Semanišin. "On some variations of extremal graph problems." Discussiones Mathematicae Graph Theory 17.1 (1997): 67-76. <http://eudml.org/doc/270170>.

@article{GabrielSemanišin1997,
abstract = { A set P of graphs is termed hereditary property if and only if it contains all subgraphs of any graph G belonging to P. A graph is said to be maximal with respect to a hereditary property P (shortly P-maximal) whenever it belongs to P and none of its proper supergraphs of the same order has the property P. A graph is P-extremal if it has a the maximum number of edges among all P-maximal graphs of given order. The number of its edges is denoted by ex(n, P). If the number of edges of a P-maximal graph is minimum, then the graph is called P-saturated and its number of edges is denoted by sat(n, P). In this paper, we consider two famous problems of extremal graph theory. We shall translate them into the language of P-maximal graphs and utilize the properties of the lattice of all hereditary properties in order to establish some general bounds and particular results. Particularly, we shall investigate the behaviour of sat(n,P) and ex(n,P) in some interesting intervals of the mentioned lattice. },
author = {Gabriel Semanišin},
journal = {Discussiones Mathematicae Graph Theory},
keywords = {hereditary properties of graphs; maximal graphs; extremal graphs; saturated graphs; hereditary graph properties},
language = {eng},
number = {1},
pages = {67-76},
title = {On some variations of extremal graph problems},
url = {http://eudml.org/doc/270170},
volume = {17},
year = {1997},
}

TY - JOUR
AU - Gabriel Semanišin
TI - On some variations of extremal graph problems
JO - Discussiones Mathematicae Graph Theory
PY - 1997
VL - 17
IS - 1
SP - 67
EP - 76
AB - A set P of graphs is termed hereditary property if and only if it contains all subgraphs of any graph G belonging to P. A graph is said to be maximal with respect to a hereditary property P (shortly P-maximal) whenever it belongs to P and none of its proper supergraphs of the same order has the property P. A graph is P-extremal if it has a the maximum number of edges among all P-maximal graphs of given order. The number of its edges is denoted by ex(n, P). If the number of edges of a P-maximal graph is minimum, then the graph is called P-saturated and its number of edges is denoted by sat(n, P). In this paper, we consider two famous problems of extremal graph theory. We shall translate them into the language of P-maximal graphs and utilize the properties of the lattice of all hereditary properties in order to establish some general bounds and particular results. Particularly, we shall investigate the behaviour of sat(n,P) and ex(n,P) in some interesting intervals of the mentioned lattice.
LA - eng
KW - hereditary properties of graphs; maximal graphs; extremal graphs; saturated graphs; hereditary graph properties
UR - http://eudml.org/doc/270170
ER -

## References

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10. [10] M. Simonovits, Extremal graph problems with symmetrical extremal graphs. Additional chromatical conditions, Discrete Math. 7 (1974) 349-376; MR49#2459. Zbl0274.05113
11. [11] M. Simonovits, Extremal graph theory, in: L.W. Beineke and R.J. Wilson, eds., Selected Topics in Graph Theory vol. 2 (Academic Press, London, 1983) 161-200.
12. [12] P. Turán, On an extremal problem in graph theory, Mat. Fiz. Lapok 48 (1941) 436-452 (Hungarian); MR8,284j.
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14. [14] L. Kászonyi and Z. Tuza, Saturated graphs with minimal number of edges, J. Graph Theory 10 (1986) 203-210, doi: 10.1002/jgt.3190100209. Zbl0593.05041

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