Block relations in formal fuzzy concept analysis

One of the main problems in formal concept analysis (especially in fuzzy setting) is to reduce a concept lattice of a formal context to appropriate size to make it graspable and understandable. A natural way to do it is to substitute the formal context by its block relation which is equivalent to factorization of the concept lattice by a complete tolerance. We generalize known results on the correspondence of block relations of formal contexts and complete tolerances on concept lattices to fuzzy setting and we provide an illustrative example of using block relations to reduce the size of a concept lattice.     

Closure-based constraints in formal concept analysis

We present a method of imposing constraints in extracting formal concepts (equivalently, closed itemsets or fixpoints of Galois connections) from a binary relation. The constraints are represented by closure operators and their purpose is to mimic background knowledge a user may have of the data. The idea is to consider and extract only these itemsets that are compatible with the background knowledge. As a result, the method extracts less clusters, those that are interesting from the user point of view, in a shorter time. The method makes it also possible to extract minimal bases of attribute dependencies in the input data that are compatible with the background knowledge. We provide examples of several particular types of constraints including those that appeared in the literature in the past and present algorithms to compute the constrained formal concepts and attribute implications.     

Ordinally equivalent data: A measurement-theoretic look at formal concept analysis of fuzzy attributes

We show that if two fuzzy relations, representing data tables with graded attributes, are ordinally equivalent then their concept lattices with respect to the Gödel operations on chains are (almost) isomorphic and that the assumption of Gödel operations is essential. We argue that measurement-theoretic results like this one are important for pragmatic reasons in relational data modeling and outline issues for future research.     

On computable automorphisms in formal concept analysis

Under study are the automorphism groups of computable formal contexts. We give a general method to transform results on the automorphisms of computable structures into results on the automorphisms of formal contexts. Using this method, we prove that the computable formal contexts and computable structures actually have the same automorphism groups and groups of computable automorphisms. We construct some examples of formal contexts and concept lattices that have nontrivial automorphisms but none of them could be hyperarithmetical in any hyperarithmetical presentation of these structures. We also show that it could be happen that two formal concepts are automorphic but they are not hyperarithmetically automorphic in any hyperarithmetical presentation.     

Fixed point property and formal concept analysis

The purpose of this paper is to interpret, with the language of formal concept analysis, the fixed point free and order-preserving self-mappings of ordered sets as formal concepts of a context. With this interpretation one can derive a practicable algorithm for determining if a given finite ordered set has the fixed point property. As a side product it is proved that dismantlability of finite ordered sets can be tested in polynomial time.     

Bands in lattices of operators

We consider the lattice of regular operators on a Dedekind complete Banach lattice. We show that in general the projection onto a band generated by a lattice homomorphism need not be continuous and that the principal bands need not be closed for the operator norm. In fact it is possible to find a convergent sequence of operators all the members of which are disjoint from the limit.

     

Hahn-Banach extension theorems over the space of fuzzy elements

The conventional Hahn-Banach extension theorem over a vector space has been widely used to derive many important and interesting results in nonlinear analysis, vector optimization and mathematical economics. Although the space of fuzzy elements is not a real vector space, the Hahn-Banach extension theorems over the space of fuzzy elements and the nonstandard normed space of fuzzy elements are presented in this paper. The work also shows the possible applications of the fuzzy-valued problems to nonlinear analysis, vector optimization and mathematical economics.     

Compact operators in Banach lattices

Disjoint sequence methods from the theory of Riesz spaces are used to study compact operators on Banach lattices. A principal new result of the paper is that each positive map from a Banach latticeE to a Banach latticeF with compact majorant is itself compact provided the norms onE′ andF are order continuous.     

The generalized doubling construction and formal concept analysis

Presented by R. Freese.     

Vector lattices of weakly compact operators on Banach lattices

A result of Aliprantis and Burkinshaw shows that weakly compact operators from an AL-space into a KB-space have a weakly compact modulus. Groenewegen characterised the largest class of range spaces for which this remains true whenever the domain is an AL-space and Schmidt proved a dual result. Both of these authors used vector-valued integration in their proofs. We give elementary proofs of both results and also characterise the largest class of domains for which the conclusion remains true whenever the range space is a KB-space. We conclude by studying the order structure of spaces of weakly compact operators between Banach lattices to prove results analogous to earlier results of one of the authors for spaces of compact operators.

     

On Banach lattices of operators

Let Λ₁ and Λ₂ be infinte-dimensional, Banach lattices such thatc _o is not finitely representable in Λ₂. Then the bounded linear operators from Λ₁ to Λ₂ form a lattice if and only if Λ₁ is an abstract AL space.     

Banach格上的b-几乎Dunford-Pettis算子

首先给出了Banah格上的b-几乎Dunford-Pettis算子的定义;其次,研究了b-几乎Dunford-Pettis算子的相关性质,如b-几乎Dunford-Pettis算子的等价刻画,构成空间的性质,以及控制性;最后,研究了b-几乎DunfordPettis算子与相关算子(b-弱紧算子,弱紧算子,几乎Dunford-Pettis算子)间的关系.     

An extension to possibilistic fuzzy cluster analysis

We explore an approach to possibilistic fuzzy clustering that avoids a severe drawback of the conventional approach, namely that the objective function is truly minimized only if all cluster centers are identical. Our approach is based on the idea that this undesired property can be avoided if we introduce a mutual repulsion of the clusters, so that they are forced away from each other. We develop this approach for the possibilistic fuzzy c-means algorithm and the Gustafson–Kessel algorithm. In our experiments we found that in this way we can combine the partitioning property of the probabilistic fuzzy c-means algorithm with the advantages of a possibilistic approach w.r.t. the interpretation of the membership degrees.     

Hahn-Banach extension operators and spaces of operators

Let be Banach spaces and let be closed operator ideals. Let be a Banach space having the Radon-Nikodým property. The main results are as follows. If is a Hahn-Banach extension operator, then there exists a set of Hahn-Banach extension operators , , such that , where . If is an ideal in for all equivalently renormed versions of , then there exist Hahn-Banach extension operators and such that .

     

Tensorial decomposition of concept lattices

A tensor product for complete lattices is studied via concept lattices. A characterization as a universal solution and an ideal representation of the tensor products are given. In a large class of concept lattices which contains all finite ones, the subdirect decompositions of a tensor product can be determined by the subdirect decompositions of its factors. As a consequence, one obtains that the tensor product of completely subdirectly irreducible concept lattices of this class is again completely subdirectly irreducible. Finally, applications to conceptual measurement are discussed.Dedicated to Ernst-August Behrens on the occasion of his seventieth birthday.     

模糊蕴涵格理论

模糊蕴涵代数,在文献中简称为FI代数,最初由吴望名先生于1990年提出,至今已经有许多研究成果.文中综述有关FI代数的概念,性质等主要研究工作,同时给出这类代数的一些新的性质.重点强调构成格结构的FI代数,称之为模糊蕴涵格,简称为FI格.这类代数结构与模糊逻辑中几个重要的代数系统具有紧密的联系,文中将揭示这些联系,一些重要的模糊逻辑代数系统都是FI格类的子类.另外,所有正则FI格构成代数簇,即等式代数类.这个代数簇将在模糊逻辑与近似推理中发挥重要的作用.