On the number of frames in binary words |
| |
Authors: | Tero Harju Tomi Kärki |
| |
Affiliation: | Department of Mathematics and Turku Centre for Computer Science, University of Turku, 20014 Turku, Finland |
| |
Abstract: | A frame is a square uu, where u is an unbordered word. Let F(n) denote the maximum number of distinct frames in a binary word of length n. We count this number for small values of n and show that F(n) is at most ⌊n/2⌋+8 for all n and greater than 7n/30−? for any positive ? and infinitely many n. We also show that Fibonacci words, which are known to contain plenty of distinct squares, have only a few frames. Moreover, by modifying the Thue-Morse word, we prove that the minimum number of occurrences of frames in a word of length n is ⌈n/2⌉−2. |
| |
Keywords: | Frame Square Unbordered word Fibonacci word Thue-Morse word |
本文献已被 ScienceDirect 等数据库收录! |
|