Twisted conjugacy and commensurability invariance
Twisted conjugacy and commensurability invariance
Abstract A group ๐บ is said to have property <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:msub> <m:mi>R</m:mi> <m:mi mathvariant="normal">โ</m:mi> </m:msub> </m:math> R_{\infty} if, for every automorphism <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:mrow> <m:mi>ฯ</m:mi> <m:mo>โ</m:mo> <m:mrow> <m:mi>Aut</m:mi> <m:mo>โข</m:mo> <m:mrow> <m:mo stretchy="false">(</m:mo> <m:mi>G</m:mi> <m:mo stretchy="false">)</m:mo> </m:mrow> </m:mrow> </m:mrow> </m:math> \varphi\in\mathrm{Aut}(G) , the cardinality of the set of ๐-twisted conjugacy โฆ