We explore the relations between Langford (2, m, 3m)-sequences on the one hand and complete and addtive permutations on the other. We consider in this context permutations with a certain "splitting" property and report on the results of some computer studies.
Extended Langford Sequences with Small Defects
✍ Scribed by Václav Linek; Zhike Jiang
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 284 KB
- Volume
- 84
- Category
- Article
- ISSN
- 0097-3165
No coin nor oath required. For personal study only.
✦ Synopsis
A k-extended Langford sequence of defect d and length m is a sequence s 1 , s 2 , ..., s 2m+1 in which s k ==, where = is the null symbol, and each other member of the sequence comes from the set [d, d+1, ..., d+m&1]. Each j # [d, d+1, ..., d+m&1] occurs exactly twice in the sequence, and the two occurrences are separated by exactly j&1 symbols. In this paper we prove that when d=2, 3, the necessary conditions for the existence of such a sequence are sufficient. 1998 Academic Press Theorem 1.1 [3]. A Langford sequence of defect d and length m exists if and only if (1) m 2d&1 and
(2) m#0, 1 (mod 4) for d odd and m#0, 3 (mod 4) for d even.
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