摘要
In this paper, we investigate the factor properties and gap sequence of the Tri- bonacci sequence, the fixed point of the substitution σ（a, b, c） = （ab, ac, a）. Let Wp be the p-th occurrence of w and Gp（ω） be the gap between Wp and Wp＋l. We introduce a notion of kernel for each factor w, and then give the decomposition of the factor w with respect to its kernel. Using the kernel and the decomposition, we prove the main result of this paper： for each factor w, the gap sequence {Gp（ω）}p≥1 is the Tribonacci sequence over the alphabet {G1 （ω）, G2（ω）, G4（ω）}, and the expressions of gaps are determined completely. As an application, for each factor w and p C ∈N, we determine the position of Wp. Finally we introduce a notion of spectrum for studying some typical combinatorial properties, such as power, overlap and separate of factors.
In this paper, we investigate the factor properties and gap sequence of the Tri- bonacci sequence, the fixed point of the substitution σ（a, b, c） = （ab, ac, a）. Let Wp be the p-th occurrence of w and Gp（ω） be the gap between Wp and Wp＋l. We introduce a notion of kernel for each factor w, and then give the decomposition of the factor w with respect to its kernel. Using the kernel and the decomposition, we prove the main result of this paper： for each factor w, the gap sequence {Gp（ω）}p≥1 is the Tribonacci sequence over the alphabet {G1 （ω）, G2（ω）, G4（ω）}, and the expressions of gaps are determined completely. As an application, for each factor w and p C ∈N, we determine the position of Wp. Finally we introduce a notion of spectrum for studying some typical combinatorial properties, such as power, overlap and separate of factors.
基金
supported by grants from the National Science Foundation of China(11431007
11271223
11371210)
