منابع مشابه
Skew-merged Simple Permutations
The simple permutations in two permutation classes — the 321-avoiding permutations and the skew-merged permutations — are enumerated using a uniform method. In both cases, these enumerations were known implicitly, by working backwards from the enumeration of the class, but the simple permutations had not been enumerated explicitly. In particular, the enumeration of the simple skew-merged permut...
متن کاملFast property testing and metrics for permutations
The goal of property testing is to quickly distinguish between objects which satisfy a property and objects that are -far from satisfying the property. There are now several general results in this area which show that natural properties of combinatorial objects can be tested with “constant” query complexity, depending only on and the property, and not on the size of the object being tested. Th...
متن کاملPseudorandom permutations with the fast forward property
We describe an efficient construction of pseudorandom permutations P with the fast forward property, namely, such that for each m the computation of Pm(x) can be done with a constant number of calls to an underlying pseudorandom permutation. This solves an open problem of Naor and Reingold. 1. Ordered cycle structures Definition 1.1. Let Ω be a finite, well-ordered set. The ordered cycle struct...
متن کاملUniversal property of skew P BW extensions
In this paper we prove the universal property of skew PBW extensions generalizing this way the well known universal property of skew polynomial rings. For this, we will show first a result about the existence of this class of non-commutative rings. Skew PBW extensions include as particular examples Weyl algebras, enveloping algebras of finite-dimensional Lie algebras (and its quantization), Art...
متن کاملPermutations with a distinct difference property
The topic of this paper arose out of a consideration of Costas sequences, which are used in sonar and radar applications. These sequences have the de/ning property that all di!erences of elements the same distance apart, are di!erent. Several in/nite families of Costas sequences are known; but there are many existence questions for length ¿ 32. In this article, we restrict ourselves to sequence...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Journal of Combinatorial Theory, Series A
سال: 2019
ISSN: 0097-3165
DOI: 10.1016/j.jcta.2019.06.005