%0 Journal Article
%T Presentation by conjugation for $A_1$-type extended affine Weyl groups
%A Saeid Azam
%A Valiollah Sahsanaei
%J Mathematics
%D 2006
%I arXiv
%X There is a well-known presentation for finite and affine Weyl groups called the {\it presentation by conjugation}. Recently, it has been proved that this presentation holds for certain sub-classes of extended affine Weyl groups, the Weyl groups of extended affine root systems. In particular, it is shown that if nullity is $\leq 2$, an $A_1$-type extended affine Weyl group has the presentation by conjugation. We set up a general framework for the study of simply laced extended affine Weyl groups. As a result, we obtain certain necessary and sufficient conditions for an $A_1$-type extended affine Weyl group of arbitrary nullity to have the presentation by conjugation. This gives an affirmative answer to a conjecture that there are extended affine Weyl groups which are not presented by "presentation by conjugation".
%U http://arxiv.org/abs/math/0607149v2