Popis: |
We will say that two subshifts are essentially conjugate if they are topologically conjugate on the complement of their periodic points. In 1990, Susan Williams presented an example of a sofic shift that is not topologically conjugate to a renewal system. We show that the example of Williams is essentially conjugate to a renewal system. We also present an example of a renewal system that is essentially conjugate to a shift of finite type but not topologically conjugate to a shift of finite type. Finally, we prove that all renewal systems that meet a certain technical condition are essentially conjugate to a shift of finite type. |