An Extension Theorem for Closing Maps of Shifts of Finite Type
Jonathan J. Ashley · Transactions of the American Mathematical Society · 1993
If there exists some right-closing factor map $\pi :{\Sigma _A} \to {\Sigma _B}$ between aperiodic shifts of finite type, then any right-closing map $\varphi :X \to {\Sigma _B}$ from any shift of finite type $X$ contained in ${\Sigma _A}$ can be extended to a right-closing factor map from all of ${\Sigma _A}$ onto ${\Sigma _B}$. We prove this and give some consequences.