Let 1<q<2 and Λ(q)=k=0∑nakqk∣ak∈{−1,0,1},n≥1. It is well known that if q is not a root of a polynomial with
coefficients 0,±1, then Λ(q) is dense in R. We give
several sufficient conditions for the denseness of Λ(q) when q is a
root of such a polynomial. In particular, we prove that if q is not a Perron
number or it has a conjugate α such that q∣α∣<1, then
Λ(q) is dense in R.Comment: 10 pages, no figure