Does This Property of Words Have a Name?












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Let us say an infinite word $w=w_1w_2cdots$ over a finite alphabet ${a_1,ldots,a_r}$ is good if there exists a positive integer $m$ such that none of the words $a_1^m,ldots,a_r^m$ appear as factors of $w$. Equivalently, saying $w$ is good means that it does not contain arbitrarily long factors that use only one letter. Does this "good" property already have a different name in the literature?










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  • $begingroup$
    It's an example of "shift of finite type" . But there are other examples not of this form.
    $endgroup$
    – kimchi lover
    Jan 28 at 23:42










  • $begingroup$
    As mentioned, the set of sequences $X_{mathcal{F}}$ such that no word in the finite set $mathcal{F} = {a_i^m mid 1 leq i leq r}$ appears in any sequence in $X_{mathcal{F}}$ is called a shift of finite type (SFT) or topological Markov shift. You might also be interested in the related notion of square-free and $k$-free sequences (not quite the same, but of the same spirit).
    $endgroup$
    – Dan Rust
    Jan 28 at 23:48


















1












$begingroup$


Let us say an infinite word $w=w_1w_2cdots$ over a finite alphabet ${a_1,ldots,a_r}$ is good if there exists a positive integer $m$ such that none of the words $a_1^m,ldots,a_r^m$ appear as factors of $w$. Equivalently, saying $w$ is good means that it does not contain arbitrarily long factors that use only one letter. Does this "good" property already have a different name in the literature?










share|cite|improve this question









$endgroup$












  • $begingroup$
    It's an example of "shift of finite type" . But there are other examples not of this form.
    $endgroup$
    – kimchi lover
    Jan 28 at 23:42










  • $begingroup$
    As mentioned, the set of sequences $X_{mathcal{F}}$ such that no word in the finite set $mathcal{F} = {a_i^m mid 1 leq i leq r}$ appears in any sequence in $X_{mathcal{F}}$ is called a shift of finite type (SFT) or topological Markov shift. You might also be interested in the related notion of square-free and $k$-free sequences (not quite the same, but of the same spirit).
    $endgroup$
    – Dan Rust
    Jan 28 at 23:48
















1












1








1


0



$begingroup$


Let us say an infinite word $w=w_1w_2cdots$ over a finite alphabet ${a_1,ldots,a_r}$ is good if there exists a positive integer $m$ such that none of the words $a_1^m,ldots,a_r^m$ appear as factors of $w$. Equivalently, saying $w$ is good means that it does not contain arbitrarily long factors that use only one letter. Does this "good" property already have a different name in the literature?










share|cite|improve this question









$endgroup$




Let us say an infinite word $w=w_1w_2cdots$ over a finite alphabet ${a_1,ldots,a_r}$ is good if there exists a positive integer $m$ such that none of the words $a_1^m,ldots,a_r^m$ appear as factors of $w$. Equivalently, saying $w$ is good means that it does not contain arbitrarily long factors that use only one letter. Does this "good" property already have a different name in the literature?







reference-request terminology definition combinatorics-on-words






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share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Jan 28 at 23:40









Colin DefantColin Defant

712312




712312












  • $begingroup$
    It's an example of "shift of finite type" . But there are other examples not of this form.
    $endgroup$
    – kimchi lover
    Jan 28 at 23:42










  • $begingroup$
    As mentioned, the set of sequences $X_{mathcal{F}}$ such that no word in the finite set $mathcal{F} = {a_i^m mid 1 leq i leq r}$ appears in any sequence in $X_{mathcal{F}}$ is called a shift of finite type (SFT) or topological Markov shift. You might also be interested in the related notion of square-free and $k$-free sequences (not quite the same, but of the same spirit).
    $endgroup$
    – Dan Rust
    Jan 28 at 23:48




















  • $begingroup$
    It's an example of "shift of finite type" . But there are other examples not of this form.
    $endgroup$
    – kimchi lover
    Jan 28 at 23:42










  • $begingroup$
    As mentioned, the set of sequences $X_{mathcal{F}}$ such that no word in the finite set $mathcal{F} = {a_i^m mid 1 leq i leq r}$ appears in any sequence in $X_{mathcal{F}}$ is called a shift of finite type (SFT) or topological Markov shift. You might also be interested in the related notion of square-free and $k$-free sequences (not quite the same, but of the same spirit).
    $endgroup$
    – Dan Rust
    Jan 28 at 23:48


















$begingroup$
It's an example of "shift of finite type" . But there are other examples not of this form.
$endgroup$
– kimchi lover
Jan 28 at 23:42




$begingroup$
It's an example of "shift of finite type" . But there are other examples not of this form.
$endgroup$
– kimchi lover
Jan 28 at 23:42












$begingroup$
As mentioned, the set of sequences $X_{mathcal{F}}$ such that no word in the finite set $mathcal{F} = {a_i^m mid 1 leq i leq r}$ appears in any sequence in $X_{mathcal{F}}$ is called a shift of finite type (SFT) or topological Markov shift. You might also be interested in the related notion of square-free and $k$-free sequences (not quite the same, but of the same spirit).
$endgroup$
– Dan Rust
Jan 28 at 23:48






$begingroup$
As mentioned, the set of sequences $X_{mathcal{F}}$ such that no word in the finite set $mathcal{F} = {a_i^m mid 1 leq i leq r}$ appears in any sequence in $X_{mathcal{F}}$ is called a shift of finite type (SFT) or topological Markov shift. You might also be interested in the related notion of square-free and $k$-free sequences (not quite the same, but of the same spirit).
$endgroup$
– Dan Rust
Jan 28 at 23:48












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