Geometric function theory: Difference between revisions

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{{Short description|Study of space and shapes locally given by a convergent power series}}
'''Geometric function theory''' is the study of [[Geometry|geometric]] properties of [[analytic function]]s. A fundamental result in the theory is the [[Riemann mapping theorem]].
 
==Topics in geometric function theory==
The following are some of the most important topics in geometric function theory:<ref>Hurwitz-Courant, ''Vorlesunger über allgemeine Funcktionen Theorie'', 1922 (4th ed., appendix by H. Röhrl, vol. 3, ''Grundlehren der mathematischen Wissenschaften''. Springer, 1964.)</ref><ref>MSC classification for 30CXX, Geometric Function Theory, retrieved from http://www.ams.org/msc/msc2010.html on September 16, 2014.</ref>
 
===Conformal maps===
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[[Image:Conformal map.svg|right|thumb|A rectangular grid (top) and its image under a conformal map ''f'' (bottom). It is seen that ''f'' maps pairs of lines intersecting at 90° to pairs of curves still intersecting at 90°.]]
 
A '''conformal map''' is a [[function (mathematics)|function]] which preserves [[angle]]s locally. In the most common case the function has a [[Domain of a function|___domain]] and [[Range (mathematics)of a function|range]] in the [[complex plane]].
 
More formally, a map,
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Then, |''f''(''z'')| ≤ |''z''| for all ''z'' in '''D''' and |''f′''(0)| ≤ 1.
 
Moreover, if |''f''(''z'')| = |''z''| for some non-zero ''z'' or if |''f′''(0)| = 1, then ''f''(''z'') = ''az'' for some ''a'' in '''C''' with |''a''| =(necessarily) equal to 1.</blockquote>
 
===Maximum principle===
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==References==
{{Reflist}}
* {{Citation |last=Ahlfors |first=Lars |author-link=Lars Ahlfors |title=Zur Theorie der Überlagerungsflächen |journal=[[Acta Mathematica]] |volume=65 |issue=1 |pages=157–194 |year=1935 |issn=0001-5962 |language=de |doi=10.1007/BF02420945 |jfm=61.0365.03 |zbl=0012.17204 |doi-access=free}}.
* Hurwitz-Courant, ''Vorlesunger über allgemeine Funcktionen Theorie'', 1922 (4th ed.,appendix by H. Röhrl, vol. 3, ''Grundlehren der mathematischen Wissenschaften''. Springer, 1964.)
*{{Citation |last=Grötzsch |first=Herbert |author-link=Herbert Grötzsch |title=Über einige Extremalprobleme der konformen Abbildung. I, II. |language=de |year=1928 |journal=[[Berichte über die Verhandlungen der Königlich Sächsischen Gesellschaft der Wissenschaften zu Leipzig. Mathematisch-Physische Classe]] |volume=80 |pages=367–376, 497–502 |jfm=54.0378.01}}.
* Hurwitz-Courant, ''Vorlesunger über allgemeine Funcktionen Theorie'', 1922 (4th ed., appendix by H. Röhrl, vol. 3, ''Grundlehren der mathematischen Wissenschaften''. Springer, 1964.)
*{{cite book |title=Geometric Function Theory: Explorations in Complex Analysis|
first=Steven|last=Krantz|publisher=Springer|year=2006|isbn=0-8176-4339-7}}
*{{Cite journal | last1 = Bulboacă | first1 = T. | last2 = Cho | first2 = N. E. | last3 = Kanas | first3 = S. A. R. | title = New Trends in Geometric Function Theory 2011 | doi = 10.1155/2012/976374 | journal = International Journal of Mathematics and Mathematical Sciences | volume = 2012 | pages = 11–2 | year = 2012 | pmidurl = http://downloads.hindawi.com/journals/ijmms/2010/906317.pdf | pmcdoi-access = free }}
*{{cite book | isbn = 978-0821852705 | title = Conformal Invariants: Topics in Geometric Function Theory | last1 = Ahlfors | first1 = Lars | year = 2010 | publisher = AMS Chelsea Publishing | pages = }}
 
[[Category:Analytic functions|*]]