Davenport-Schinzel sequences are sequences that give rise to a hierarchy of functions that grow extremely close to linearly. An \((n,s)\) Davenport-Schinzel sequence is a sequence \(a_1,a_2,\ldots,a_m\) where \(a_i\) are integers in \([1,n]\), such that:
* \(a_i
eq a_{i+1}\)
* There is no sequence \(i_1 < i_2 < \cdots < i_{s + 2}\) such that \(a_{i_1} = a_{i_3} = a_{i_5} = \ldots
eq a_{i_2} = a_{i_4} = a_{i_6} = \ldots\).
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rdfs:label
| - Davenport-Schinzel sequence
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rdfs:comment
| - Davenport-Schinzel sequences are sequences that give rise to a hierarchy of functions that grow extremely close to linearly. An \((n,s)\) Davenport-Schinzel sequence is a sequence \(a_1,a_2,\ldots,a_m\) where \(a_i\) are integers in \([1,n]\), such that:
* \(a_i
eq a_{i+1}\)
* There is no sequence \(i_1 < i_2 < \cdots < i_{s + 2}\) such that \(a_{i_1} = a_{i_3} = a_{i_5} = \ldots
eq a_{i_2} = a_{i_4} = a_{i_6} = \ldots\).
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dcterms:subject
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abstract
| - Davenport-Schinzel sequences are sequences that give rise to a hierarchy of functions that grow extremely close to linearly. An \((n,s)\) Davenport-Schinzel sequence is a sequence \(a_1,a_2,\ldots,a_m\) where \(a_i\) are integers in \([1,n]\), such that:
* \(a_i
eq a_{i+1}\)
* There is no sequence \(i_1 < i_2 < \cdots < i_{s + 2}\) such that \(a_{i_1} = a_{i_3} = a_{i_5} = \ldots
eq a_{i_2} = a_{i_4} = a_{i_6} = \ldots\). Define \(\lambda_s(n)\) as the length of the longest \((n,s)\) Davenport-Schinzel sequence. Then \(\lambda_1(n) = n\), \(\lambda_2(n) = 2n - 1\), \(\lambda_3(n) = \Theta(n\alpha(n))\) where \(\alpha\) is the inverse Ackermann function. A large number function can be extracted by defining \( ext{DS}_3(n) = \min\{m : \lambda_3(m) \geq mn\}\).
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