A proof of the extended Duval's conjecture
We give a short and elementary proof of the following stronger version of Duval's conjecture: let it be an unbordered word, and v a word of length |u| - 1, such that v is not a prefix of u. Then uv contains an unbordered word of length at least |u| + 1. (c) 2005 Elsevier B.V. All rights reserved.
unbordered words combinatorics on words duval's conjecture