Absent Subsequences in Words

@article{Kosche2021AbsentSI,
  title={Absent Subsequences in Words},
  author={Maria Kosche and Tore Ko{\ss} and Florin Manea and Stefan Siemer},
  journal={ArXiv},
  year={2021},
  volume={abs/2108.13968}
}
An absent factor of a string w is a string u which does not occur as a contiguous substring (a.k.a. factor) insidew. We extend this well-studied notion and define absent subsequences: a string u is an absent subsequence of a string w if u does not occur as subsequence (a.k.a. scattered factor) inside w. Of particular interest to us are minimal absent subsequences, i.e., absent subsequences whose every subsequence is not absent, and shortest absent subsequences, i.e., absent subsequences of… 

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