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            John C. O'Neill and Edward C. Turner 
            Test Elements and the Retract Theorem in Hyperbolic Groups 
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                | Published: | 
                July 21, 2000 | 
               
              
                | Keywords: | 
                test words, test elements, endomorphisms, automorphisms, hyperbolic groups | 
               
              
                | Subject: | 
                20E36, 20F232 | 
               
              
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			  Abstract
			  
			       We prove that in many, perhaps all, torsion free
hyperbolic groups, test elements are precisely those elements not
contained in proper retracts. We also show that all Fuchsian
groups have this property. Finally, we show that all surface
groups except Z×Z  have test elements.
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			  | Author information
 John C. O'Neill: 
DFMS, United States Air Force Academy, CO 80840-6252 
John.Oneill@usafa.af.mil 
http://www.usafa.af.mil/dfms/people/oneill.htm 
Edward C. Turner: 
Dept. of Math., University at Albany, Albany, NY 12222 
ted@math.albany.edu 
http://nyjm.albany.edu:8000/~ted 
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