L-偏序集上的闭包系统

给出L-幂集上LK-闭包系统的等价刻画。提出L-偏序集上闭包系统的概念并讨论其基本性质。最后,将经典偏序集和L-幂集上关于闭包算子和闭包系统的对应理论推广到L-偏序集上。     

L-偏序集中L_k-素闭包算子和L_k-素内部算子

本文在完备剩余格上引入了L-偏序集,给出了L-偏序集上L_k-素闭包算子和L_k-素内部算子的概念及其等价刻画,在此基础上推广得出了n重L_k-素闭包算子和n重L_k-素内部算子的概念及其等价刻画。     

L-闭包空间的s-连通性(英文)

在L-闭包空间中引入了s-连通性的概念,讨论了s-连通性的基本性质,推广了模糊拓扑分子格里关于s-连通性的相关结果.     

L-余拓扑Vs.广义粗集

引入L-余覆盖广义粗集的概念,证明研究该广义粗集的上、下近似与研究L-余拓扑的余子基生成的闭包和内部是等价的,并且以此为基础,讨论该广义粗集的性质.     

Fuzzifying闭包系统的研究

在Fuzzifying(模糊化)数学的框架下,建立了Fuzzifying闭包系统和Birkhoff型Fuzzifying闭包算子的概念; 引入了Fuzzifying闭包空间范畴和Fuzzifying闭包系统空间范畴,并从范畴论的角度证明Birkhoff型Fuzzifying闭包算子与Fuzzifying闭包系统是协调的.最后文中还得到Fuzzifying闭包空间范畴和Fuzzifying闭包系统空间范畴可以嵌入到Birkhoff型L-闭包空间范畴这一重要结果.     

L-抽象基与模糊Round理想完备化

首先引入了L-抽象基和模糊Round理想,并给出模糊Round理想的等价刻画,证明了一个模糊Domain的模糊Round理想同构于该模糊Domain。其次,研究了L-抽象基的模糊Round理想完备化,且证明了模糊偏序集的模糊Round理想完备化是模糊Domain。最后证明了模糊Domain的连续收缩是模糊Domain。     

有限格，闭包系统和闭包算子

本文引进了新的闭包系统,新的闭包算子等概念,研究了它们之间的相互关系,给出了由闭包系统来表示有限原子格的表示定理,证明了分别以这些数学结构为对象,以它们之间的同态映射作为态射,所对应的格范畴和对应的闭包系统范畴是范畴等价的.     

L-模糊弱理想与L-模糊近理想

给出了L-模糊弱理想与L-模糊近理想的概念并借助于L-模糊集的几种截集给出了它们的刻画,研究了它们的运算性质。     

L-闭包空间的βc-紧性

在L-闭包空间中给出了βc-开集、La-βc-开覆盖的概念,引入了βc-紧集和βc-紧空间.证明它保持了L-拓扑空间中的主要结论:如闭遗传性、好的推广和弱拓扑不变性等好的性质.     

FS-偏序集和连续L-偏序集

引入了FS-偏序集和连续L-偏序集概念,探讨了FS-偏序集和连续L-偏序集的性质.主要结果有(1)每一FS-偏序集都是有限上集生成的,因而是Scott紧的;(2)证明了FS-偏序集(连续L-偏序集)的定向完备化是FS-偏序集(连续L-偏序集);(3)一个偏序集是一个FS-Domain当且仅当它为Lawson紧的FS-偏序集;(4)FS-偏序集(连续L-偏序集)去掉部分极大元后还是FS-偏序集(连续L-偏序集).     

Uniquely Complemented Posets

We study complementation in bounded posets. It is known and easy to see that every complemented distributive poset is uniquely complemented. The converse statement is not valid, even for lattices. In the present paper we provide conditions that force a uniquely complemented poset to be distributive. For atomistic resp. atomic posets as well as for posets satisfying the descending chain condition we find sufficient conditions in the form of so-called LU-identities. It turns out that for finite posets these conditions are necessary and sufficient.     

The rank-generating functions of upho posets

Upper homogeneous finite type (upho) posets are a large class of partially ordered sets with the property that the principal order filter at every vertex is isomorphic to the whole poset. Well-known examples include k-ary trees, the grid graphs, and the Stern poset. Very little is known about upho posets in general. In this paper, we construct upho posets with Schur-positive Ehrenborg quasisymmetric functions, whose rank-generating functions have rational poles and zeros. We also categorize the rank-generating functions of all planar upho posets. Finally, we prove the existence of an upho poset with an uncomputable rank-generating function.     

A note on random k-dimensional posets

In 2009, Janson [Poset limits and exchangeable random posets, Institut Mittag-Leffler preprint, 36pp, arXiv:0902.0306] extended the recent theory of graph limits to posets, defining convergence for poset sequences and proving that every such sequence has a limit object. In this paper, we focus on k-dimensional poset sequences. This restriction leads to shorter proofs and to a more intuitive limit object. As before, the limit object can be used as a model for random posets, which generalizes the well known random k-dimensional poset model. This investigation also leads to a definition of quasirandomness for k-dimensional posets, which can be captured by a natural distance that measures the discrepancy of a k-dimensional poset.     

Prime, irreducible elements and coatoms in posets

In this paper, some properties of prime elements, pseudoprime elements, irreducible elements and coatoms in posets are investigated. We show that the four kinds of elements are equivalent to each other in finite Boolean posets. Furthermore, we demonstrate that every element of a finite Boolean poset can be represented by one kind of them. The example presented in this paper indicates that this result may not hold in every finite poset, but all the irreducible elements are proved to be contained in each order generating set. Finally, the multiplicative auxiliary relation on posets and the notion of arithmetic poset are introduced, and some properties about them are generalized to posets.     

Reversible and Bijectively Related Posets

Call a poset reversible if every of its order-preserving self-bijections is an automorphism. Call two posets bijectively related if from each of the two posets exists an order-preserving bijection to the other. We present two examples of pairs of non-isomorphic, bijectively related posets and an example of a non-reversible poset that is bijectively related only to itself. Also, three classes of reversible posets are described and a sufficient condition for an order-preserving bijection to be an isomorphism is presented.     

Prime ideals in 0-distributive posets

In the first section of this paper, we prove an analogue of Stone’s Theorem for posets satisfying DCC by using semiprime ideals. We also prove the existence of prime ideals in atomic posets in which atoms are dually distributive. Further, it is proved that every maximal non-dense (non-principal) ideal of a 0-distributive poset (meet-semilattice) is prime. The second section focuses on the characterizations of (minimal) prime ideals in pseudocomplemented posets. The third section deals with the generalization of the classical theorem of Nachbin. In fact, we prove that a dually atomic pseudocomplemented, 1-distributive poset is complemented if and only if the poset of prime ideals is unordered. In the last section, we have characterized 0-distributive posets by means of prime ideals and minimal prime ideals.     

Order varieties generated by finite posets

In a 1981 paper, Duffus and Rival define an order variety as a class of posets that is closed under the formation of products and retracts. They also introduce the notion of an irreducible poset. In the present paper we define nonextendible colored posets and certain minimal nonextendible colored posets that we call zigzags. We characterize via nonextendible colored posets the order varieties generated by a set of posets. If the generating set contains only finite posets our characterization is via zigzags. By using these theorems we give a characterization of finite irreducible posets.As an application we show that two different finite irreducible posets generate two different order varieties. We also show that there is a poset which has two different representations by irreducible posets. We thereby settle two open problems listed in the Duffus and Rival paper.     

A Poset Fiber Theorem for Doubly Cohen-Macaulay Posets and Its Applications

This paper studies topological properties of the lattices of non-crossing partitions of types A and B and of the poset of injective words. Specifically, it is shown that after the removal of the bottom and top elements (if existent) these posets are doubly Cohen-Macaulay. This strengthens the well-known facts that these posets are Cohen-Macaulay. Our results rely on a new poset fiber theorem which turns out to be a useful tool to prove double (homotopy) Cohen- Macaulayness of a poset. Applications to complexes of injective words are also included.     

Hypercontinuous Posets

The concepts of hypercontinuous posets and generalized completely continuous posets are introduced. It is proved that for a poset P the following three conditions are equivalent:(1) P is hypercontinuous;(2) the dual of P is generalized completely continuous;(3) the normal completion of P is a hypercontinuous lattice. In addition, the relational representation and the intrinsic characterization of hypercontinuous posets are obtained.