Reconstruction of the Neighborhood Deck of an Ordered Set

We show that the neighborhood deck of an ordered set can be reconstructed from the deck of one point deleted subsets. As a consequence of the above results we reconstruct some maximal cards and present short new proofs of the reconstructibility of ordered sets of width 2 and of the recognizability of N-free ordered sets. We also reconstruct the maximal cards of N-free ordered sets.     

Reconstruction of N-free Ordered Sets

We prove that N-free ordered sets are reconstructible.     

On Ordered Sets with Isomorphic Marked Maximal Cards

We prove a necessary condition for two nonisomorphic ordered sets to have two isomorphic marked maximal cards. This condition is used to prove that ordered sets of width 3 with 2 maximal elements are reconstructible and that ordered sets of width 3 are reconstructible if we can reconstruct the marked maximal deck.     

Being a Proper Trapezoid Ordered Set Is a Comparability Invariant

It is proved that if we replace an autonomous subset of a finite proper trapezoid ordered set with a proper trapezoid ordered set, then we obtain a proper trapezoid ordered set provided the autonomous subset is not an antichain, and analogously in the k-dimensional case. As corollaries we obtain that being a proper trapezoid ordered set is a comparability invariant, more generally, proper interval dimension is a comparability invariant.     

偏序集上蕴涵代数的素滤子

偏序集上的蕴涵代数是取值于偏序集上的蕴涵逻辑联结词的一种代数抽象.以偏序集上蕴涵代数中由蕴涵算子引入的逻辑运算t-余范为工具,讨论了偏序集上蕴涵代数的一些性质,然后引入了偏序集上蕴涵代数的素滤子的概念,讨论了素滤子在一定条件下的性质,并给出了一个MP滤子成为素滤子的条件.     

On Pseudocomplemented and Stone Ordered Sets

The aim of this paper is to characterize both the pseudocomplemented and Stone ordered sets in a manner similar to that used previously for Boolean and distributive ordered sets. The sublattice G(A) of the Dedekind–Mac Neille completion DM(A) of an ordered set A generated by A is said to be the characteristic lattice of A. We will show that there are distributive pseudocomplemented ordered sets whose characteristic lattices are not pseudocomplemented. We can define a stronger notion of pseudocomplementedness by demanding that both A and G(A) be pseudocomplemented. It turns out that the two concepts are the same for finite and Stone ordered sets.     

3-连通3-正则图中的可序子集

图G的k元点集X={x1,x2,…,xk}被称为G的k-可序子集,如果X的任意排列都按序排在G的某个圈上.称G是k-可序图,如果G的每一个k元子集都是G的k-可序子集.称G为k-可序Hamilton图,如果X的任意排列都位于G的Hamilton圈上.研究了3-连通3-正则图的可序子集的存在性问题.     

序半环的序理想

An ordered semiring is a semiring S equipped with a partial order ≤ such that the operations are monotonic and constant 0 is the least element of S.In this paper,several notions,for example,ordered ideal,minimal ideal,and maximal ideal of an ordered semiring,simple ordered semirings,etc.,are introduced.Some properties of them are given and characterizations for minimal ideals are established.Also,the matrix semiring over an ordered semiring is consid-ered.Partial results obtained in this paper are analogous to the corresponding ones on ordered semigroups,and on the matrix semiring over a semiring.     

Splittability for Partially Ordered Sets

A topological space X is said to be splittable over a class P of spaces if for every AX there exists continuous f:XYP such that f(A)f(XA) is empty. A class P of topological spaces is said to be a splittability class if the spaces splittable over P are precisely the members of P. We extend the notion of splittability to partially ordered sets and consider splittability over some elementary posets. We identify precisely which subsets of a poset can be split along over an n-point chain. Using these results it is shown that the union of two splittability classes need not be a splittability class and a necessary condition for P to be a splittability class is given.     

Identities in Ordered Sets

The concept of identities in ordered sets is introduced.     

关于序超半群的左超理想的研究

本文在序超半群中引入了极小左超理想和极大左超理想的概念, 并讨论了它们的一些相关性质. 进一步地, 引入了序超半群的弱素左超理想、拟素左超理想、拟半素左超理想及弱拟素左超理想的概念, 并讨论这四种素超理想之间的关系. 而且通过左超理想和弱~$m$-系刻画了序超半群的弱拟素左超理想. 同时, 借助于$m$-系对序超半群的拟素左超理想给出刻画. 尤其证明了序超半群$S$是强半单的当且仅当$S$的每个左超理想是$S$的包含它的所有拟素左超理想的交.     

On Pseudocomplemented and Stone Ordered Sets,Addendum

The notion of pseudocomplementedness is weakened in order to obtain a tractable and consistent property of ordered sets, in particular lattices.     

On Equivalence Relations in Ordered Sets

A relationship between equivalence relations in finite ordered sets and linear decompositions is presented.     

Maximal and Minimal Semilattices on Ordered Sets

The map which takes an element of an ordered set to its principal ideal is a natural embedding of that ordered set into its powerset, a semilattice. If attention is restricted to all finite intersections of the principal ideals of the original ordered set, then an embedding into a much smaller semilattice is obtained. In this paper the question is answered of when this construction is, in a certain arrow-theoretic sense, minimal. Specifically, a characterisation is given, in terms of ideals and filters, of those ordered sets which admit a so-called minimal embedding into a semilattice. Similarly, a candidate maximal semilattice on an ordered set can be constructed from the principal filters of its elements. A characterisation of those ordered sets that extend to a maximal semilattice is given. Finally, the notion of a free semilattice on an ordered set is given, and it is shown that the candidate maximal semilattice in the embedding-theoretic sense is the free object.     

Combinatorial Criteria for Ramifiable Ordered Sets

The tree‐property (classica in cardina theory) and its variants make sense also for directed sets and even for partially ordered sets. A combinatoria approach is developed here, with characterizations and criteria involving (inter alia) adequate families of special substructures of directed sets. These substructures form a natural hierarchy that is also investigated.     

On C-left Hyp erideals of Ordered Semihyp ergroups

In this paper, the concept of C-left hyperideals is introduced in ordered semihypergroups, and several related properties are investigated. In particular, we discuss the relationships between the greatest left hyperideals and C-left hyperideals of ordered semihypergroups. Furthermore, we introduce the concept of left bases of an ordered semihypergroup, and give out the sufficient and necessary conditions of the existence of the greatest C-left hyperideal of an ordered semihypergroup by the properties of left bases. The result about C-left ideals in ordered semigroups is generalized to the ordered semihypergroups.     

偏序集最小顶点割算法与最小费用赶工问题

在网络计划问题中,一项大的工程由许多工序合成。工序与工序之间存在着一定的前后关系,每个工序有着自己的正常加工时间和通过赶工所能达到的最短加工时间以及每赶工一天的赶工费用。设一项工程的正常工期为T天,通过对所有可能的工序赶工,整个工程能达到的最短工期为S天。本文的问题是,对于任意给定的t(S t相似文献   

偏序集的关联环的同构问题

设Ｘ是局部有限偏序集（或拟序集），Ｒ是含１的结合环，Ⅰ（Ｘ，Ｒ）是Ｒ上Ｘ的关联环，关联环的同构问题是指：问题１：怎样的环，能使环同构Ⅰ（Ｘ，Ｒ）Ⅰ（Ｘ，Ｒ）推出偏序集之间的同构Ｘ芒Ｘ’？问题２：怎样的环或偏序集，能使环同构Ⅰ（Ｘ，Ｒ）Ⅰ（Ｘ，Ｓ）推出Ｒ　Ｓ？本文证明了对唯一幂等元环（非交换），问题１有正面回答；对问题２，我们证明了对交换不可分解环Ｒ、Ｓ，由环同构Ⅰ（Ｘ，Ｒ）Ⅰ（Ｘ，Ｒ）可得到Ｒ＝Ｓ，Ｘ＝Ｘ’。     

Whaley's Theorem for Finite Lattices

Whaley's Theorem on the existence of large proper sublattices of infinite lattices is extended to ordered sets and finite lattices. As a corollary it is shown that every finite lattice L with |L|≥3 contains a proper sublattice S with |S|≥|L|^1/3. It is also shown that that every finite modular lattice L with |L|≥3 contains a proper sublattice S with |S|≥|L|^1/2, and every finite distributive lattice L with |L|≥4 contains a proper sublattice S with |S|≥3/4|L|. This revised version was published online in June 2006 with corrections to the Cover Date.