Editing Extremal graph theory (section)

==History==

{{Quote box|quote=Extremal graph theory, in its strictest sense, is a branch of graph theory developed and loved by Hungarians.|source=
Bollobás (2004)
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{{Citation | last1=Bollobás | first1=Béla | author1-link=Béla Bollobás | title=Extremal Graph Theory | publisher=[[Dover Publications]] | location=New York | isbn=978-0-486-43596-1 | year=2004}}
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Mantel's Theorem (1907) and [[Turán's theorem|Turán's Theorem]] (1941) were some of the first milestones in the study of extremal graph theory.
<ref name="b104">
{{Citation | last1=Bollobás | first1=Béla | author1-link=Béla Bollobás | title=Modern Graph Theory | publisher=[[Springer-Verlag]] | location=Berlin, New York | isbn=978-0-387-98491-9 | year=1998 | pages=103–144}}
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In particular, Turán's theorem would later on become a motivation for the finding of results such as the [[Erdős–Stone theorem]] (1946).<ref name=":0" /> This result is surprising because it connects the chromatic number with the maximal number of edges in an <math>H</math>-free graph. An alternative proof of Erdős–Stone was given in 1975, and utilised the [[Szemerédi regularity lemma]], an essential technique in the resolution of extremal graph theory problems.<ref name="b104" />
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