ON SOME FREE GROUPS, GENERATED BY MATRICES
Piotr Słanina · Demonstratio Mathematica · 2004
The interest to free groups generated by 2 x 2 matricesis known since 1947 when Sanov proved that for A = 2 the group G\ = gp{A\, C\) is a free group [22].For |A| > 2 the proof of this fact can be found in [3], The aim of this paper is to show that if A is outside of four unit circles |A ± 1| > 1 and |A ± > 1 then also G\ is a free group.