scholarly journals Jörgensen’s inequality and purely loxodromic two-generator free Kleinian groups

2019 ◽  
Vol 43 (2) ◽  
pp. 833-861 ◽  
Author(s):  
İlker Savaş YÜCE
Author(s):  
Hala Alaqad ◽  
Jianhua Gong ◽  
Gaven Martin

The principal character of a representation of the free group of rank two into [Formula: see text] is a triple of complex numbers that determines an irreducible representation uniquely up to conjugacy. It is a central problem in the geometry of discrete groups and low dimensional topology to determine when such a triple represents a discrete group which is not virtually abelian, that is, a Kleinian group. A classical necessary condition is Jørgensen’s inequality. Here, we use certain shifted Chebyshev polynomials and trace identities to determine new families of such inequalities, some of which are best possible. The use of these polynomials also shows how we can identify the principal character of some important subgroups from that of the group itself.


2019 ◽  
Vol 2019 (746) ◽  
pp. 149-170
Author(s):  
Pekka Pankka ◽  
Juan Souto

Abstract We prove that Kleinian groups whose limit sets are Cantor sets of Hausdorff dimension < 1 are free. On the other hand we construct for any ε > 0 an example of a non-free purely hyperbolic Kleinian group whose limit set is a Cantor set of Hausdorff dimension < 1 + ε.


1998 ◽  
Vol 3 (4) ◽  
pp. 355-374
Author(s):  
L. Potyagailo
Keyword(s):  

2005 ◽  
Vol 25 (4) ◽  
pp. 1305-1323 ◽  
Author(s):  
MANUEL STADLBAUER ◽  
BERND O. STRATMANN

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