A New Rapid Incremental Algorithm for Constructing Concept Lattices

Formal concept analysis has proven to be a very effective method for data analysis and rule extraction, but how to build formal concept lattices is a difficult and hot topic. In this paper, an efficient and rapid incremental concept lattice construction algorithm is proposed. The algorithm, named FastAddExtent, is seen as a modification of AddIntent in which we improve two fundamental procedures, including fixing the covering relation and searching the canonical generator. The proposed algorithm can locate the desired concept quickly by adding data fields to every concept. The algorithm is depicted in detail, using a formal context to show how the new algorithm works and discussing time and space complexity issues. We also present an experimental evaluation of its performance and comparison with AddExtent. Experimental results show that the FastAddExtent algorithm can improve efficiency compared with the primitive AddExtent algorithm.

Fast Möbius Inversion in Semimodular Lattices and ER-labelable Posets

We consider the problem of fast zeta and Möbius transforms in finite posets, particularly in lattices. It has previously been shown that for a certain family of lattices, zeta and Möbius transforms can be computed in $O(e)$ elementary arithmetic operations, where $e$ denotes the size of the covering relation. We show that this family is exactly that of geometric lattices. We also extend the algorithms so that they work in $e$ operations for all semimodular lattices, including chains and divisor lattices. Finally, for both transforms, we provide a more general algorithm that works in $e$ operations for all ER-labelable posets.

Alignments, crossings, cycles, inversions, and weak Bruhat order in permutation tableaux of type $B$

International audience Alignments, crossings and inversions of signed permutations are realized in the corresponding permutation tableaux of type $B$, and the cycles of signed permutations are understood in the corresponding bare tableaux of type $B$. We find the relation between the number of alignments, crossings and other statistics of signed permutations, and also characterize the covering relation in weak Bruhat order on Coxeter system of type $B$ in terms of permutation tableaux of type $B$. De nombreuses statistiques importantes des permutations signées sont réalisées dans les tableaux de permutations ou ”bare” tableaux de type $B$ correspondants : les alignements, croisements et inversions des permutations signées sont réalisés dans les tableaux de permutations de type $B$ correspondants, et les cycles des permutations signées sont comprises dans les ”bare” tableaux de type $B$ correspondants. Cela nous mène à relier le nombre d’alignements et de croisements avec d’autres statistiques des permutations signées, et aussi de caractériser la relation de couverture dans l’ordre de Bruhat faible sur des systèmes de Coxeter de type $B$ en termes de tableaux de permutations de type $B$.

A Content-Based Routing Algorithm in WInternet Pipe Communication Protocol

In this paper, we propose a content-based routing algorithm for WInternet Pipe Communication Protocol. A filter model based on a multilevel index structure is established to judge the covering relation between two subscription criteria. Furthermore, our routing algorithm takes advantage of covering relations and link status among nodes to build a virtual message distribution tree for each OutGate. Meanwhile, it supports nodes join and leave dynamically without impacting the routing accuracy. Analysis result shows it can reduce the message matching costs, keep the load balance among nodes and improve the transmission performance of WInternet to some extent.

Variable Precision Rough Set Model Based on Covering Relation and Uncertainty Measure

The variable precision probabilistic rough set model is based on equivalent relation and probabilistic measure. However, the requirements of equivalent relation and probabilistic measure are too strict to satisfy in some practical applications. In order to solve the above problem, a variable precision rough set model based on covering relation and uncertainty measure is proposed. Moreover, the upper and lower approximation operators of the proposed model are given, while the properties of the operators are discussed.

Maximal 0-1-fillings of moon polyominoes with restricted chain lengths and rc-graphs

International audience We show that maximal 0-1-fillings of moon polynomials, with restricted chain lengths, can be identified with certain rc-graphs, also known as pipe dreams. In particular, this exhibits a connection between maximal 0-1-fillings of Ferrers shapes and Schubert polynomials. Moreover, it entails a bijective proof showing that the number of maximal fillings of a stack polyomino $S$ with no north-east chains longer than $k$ depends only on $k$ and the multiset of column heights of $S$. Our main contribution is a slightly stronger theorem, which in turn leads us to conjecture that the poset of rc-graphs with covering relation given by generalised chute moves is in fact a lattice. Nous démontrons que les remplissages maximaux avec 0 et 1 des polyominos $L$-convexes, avec longueurs de chaînes restreintes, peuvent être identifiés avec certains $\textit{rc-graphes}$, également connus sous le nom de $\textit{pipe dreams}$. En particulier, ceci montre un lien entre ces remplissages d'un diagramme de Ferrers et les polynômes de Schubert. On en déduit en outre une preuve bijective du fait que le nombre de remplissages maximaux d'un $\textit{stack polyomino}$ $S$, avec longueurs de chaînes bornées par un entier $k$, dépend seulement de $k$ et du multi-ensemble des tailles des colonnes de $S$. Notre contribution principale est un énoncé un peu plus fort, qui nous mène à conjecturer que l'ensemble ordonné (poset) des $\textit{rc-graphes}$ est en fait un treillis.

Ordered Structures and Projections

We associate a covering relation to the usual order relation defined in the set of all idempotent endomorphisms (projections) of a finite-dimensional vector space. A characterization is given of it. This characterization makes this order an order verifying the Jordan-Dedekind chain condition. We give also a property for certain finite families of this order. More precisely, the family of parts intervening in the linear representation of diagonalizable endomorphism, that is, the orthogonal families forming a decomposition of the identity endomorphism.