Direct definition of a ternary infinite square-free sequence
We propose a new ternary infinite (even full-infinite) square-free sequence. The sequence is defined both by an iterative method and by a direct definition. Both definitions are analogous to those of the Thue-Morse sequence. The direct definition is given by a deterministic finite automaton with output. In short, the sequence is automatic. (c) 2007 Elsevier B.V. All rights reserved.
square-free sequence thue--morse sequence automatic sequence combinatorial problems symbolic dynamics