Tetration Forum
The mystery of 2 fixpoints. - Printable Version

+- Tetration Forum (https://tetrationforum.org)
+-- Forum: Tetration and Related Topics (https://tetrationforum.org/forumdisplay.php?fid=1)
+--- Forum: Mathematical and General Discussion (https://tetrationforum.org/forumdisplay.php?fid=3)
+--- Thread: The mystery of 2 fixpoints. (/showthread.php?tid=856)



The mystery of 2 fixpoints. - tommy1729 - 05/03/2014

Hello tetration freaks !

Karlin and Mcgregor showed that:

If \( f \) is a function holomorphic and single valued on the complement of a closed countable set in the extended complex plane. Let \( s_1\neq s_2 \) two fixed points of \( f \) such that \( |f'(s_0)|,|f'(s_1)|\neq 0,1 \) and \( f([s_1,s_2])\subseteq [s_1,s_2] \). Then the regular iterations at \( s_1 \) and \( s_2 \) are equal if and only if \( f \) is a fractional linear function.

[1] Karlin, S., & Mcgregor, J. ( 1968 ). Embedding iterates of analytic functions with two fixed points into continuous groups. Trans. Am. Math. Soc., 132, 137–145.

However if \( f([s_1,s_2])\subseteq [s_1,s_2] \) is not true , can we have regular iterations that are independant of the fixpoint used ?

regards

tommy1729