A Ternary Square-free Sequence Avoiding Factors Equivalent to $abcacba$

[摘要] We solve a problem of Petrova, finalizing the classification of letter patterns avoidable by ternary square-free words; we show that there is a ternary square-free word avoiding letter pattern $xyzxzyx$. In fact, we

[学科分类] 离散数学和组合数学

[关键词] Words avoiding patterns;Square-free words