Polynomial universal traversing sequences for cycles are constructible
Polynomial universal traversing sequences for cycles are constructible
复制标题
循环的多项式通用运行序列是可构造的
DOI:
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发表时间:
1988
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通讯作者:
S. Istrail
中科院分区:
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作者:
S. Istrail
The paper constructs the first polynomial universal traversing sequences for cycles, solving an open problem of S. Cook and R. Aleliunas, R. Karp, R. Lipton, L. Lovasz, C. Rackoff (1979) [2] in the case of 2-regular graphs. The existence of universal traversing sequences of size <italic>&Ogr;</italic>(<italic>d</italic><supscrpt>2</supscrpt><italic>n</italic><supscrpt>3</supscrpt><italic>logn</italic>) for <italic>n</italic>-vertex <italic>d</italic>-regular graphs was established in [2] by a probabilistic argument, which was inherently non-constructive. For the cycles, the non-constructive upper bound was improved to <italic>&Ogr;</italic> (<italic>n</italic><supscrpt>3</supscrpt>) by Janowsky (1983) [13] and Cobham (1986) [8]. Previously, the best explicit constructions for cycles were due to Bridgland (1986) and A. Bar-Noy, A. Borodin, M. Karchmer, N. Linial, and M. Werman (1986), and have size <italic>&Ogr;</italic>(<italic>n<supscrpt>log n</supscrpt></italic>).
Our universal traversing sequence has size <italic>&Ogr;</italic>(<italic>n</italic><supscrpt>4.76</supscrpt>), and can be constructed in log-space.