On the state complexity of scattered substrings and superstrings. / Okhotin, Alexander.
In: Fundamenta Informaticae, Vol. 99, No. 3, 02.07.2010, p. 325-338.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - On the state complexity of scattered substrings and superstrings
AU - Okhotin, Alexander
PY - 2010/7/2
Y1 - 2010/7/2
N2 - It is proved that the set of scattered substrings of a language recognized by an n-state DFA requires a DFA with at least 2{n/2-2} states (the known upper bound is 2n), with witness languages given over an exponentially growing alphabet. For a 3-letter alphabet, scattered substrings are shown to require at least 2{sqrt{2n+30}-6} states. A similar state complexity function for scattered superstrings is determined to be exactly 2{n-2} + 1 for an alphabet of at least n-2 letters, and strictly less for any smaller alphabet. For a 3-letter alphabet, the state complexity of scattered superstrings is at least 1/5 4sqrt{n/2}n-3/4.
AB - It is proved that the set of scattered substrings of a language recognized by an n-state DFA requires a DFA with at least 2{n/2-2} states (the known upper bound is 2n), with witness languages given over an exponentially growing alphabet. For a 3-letter alphabet, scattered substrings are shown to require at least 2{sqrt{2n+30}-6} states. A similar state complexity function for scattered superstrings is determined to be exactly 2{n-2} + 1 for an alphabet of at least n-2 letters, and strictly less for any smaller alphabet. For a 3-letter alphabet, the state complexity of scattered superstrings is at least 1/5 4sqrt{n/2}n-3/4.
KW - descriptional complexity
KW - finite automata
KW - Higman-Haines sets
KW - state complexity
KW - subsequence
KW - substring
KW - subword
UR - http://www.scopus.com/inward/record.url?scp=77954061045&partnerID=8YFLogxK
U2 - 10.3233/FI-2010-252
DO - 10.3233/FI-2010-252
M3 - Article
AN - SCOPUS:77954061045
VL - 99
SP - 325
EP - 338
JO - Fundamenta Informaticae
JF - Fundamenta Informaticae
SN - 0169-2968
IS - 3
ER -
ID: 41142137