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Some examples of true F σ δ sets

Marek Balcerzak, Udayan Darji (2000)

Colloquium Mathematicae

Let K(X) be the hyperspace of a compact metric space endowed with the Hausdorff metric. We give a general theorem showing that certain subsets of K(X) are true F σ δ sets.

Some issues of fuzzy querying in relational databases

Miroslav Hudec, Miljan Vučetić (2015)

Kybernetika

Fuzzy logic has been used for flexible database querying for more than 30 years. This paper examines some of the issues of flexible querying which seem to have potential for further research and development from theoretical and practical points of view. More precisely, defining appropriate fuzzy sets for queries, calculating matching degrees for commutative and non-commutative query conditions, preferences, merging constraints and wishes, empty and overabundant answers, and views on practical realizations...

Some methods to obtain t-norms and t-conorms on bounded lattices

Gül Deniz Çaylı (2019)

Kybernetika

In this study, we introduce new methods for constructing t-norms and t-conorms on a bounded lattice L based on a priori given t-norm acting on [ a , 1 ] and t-conorm acting on [ 0 , a ] for an arbitrary element a L { 0 , 1 } . We provide an illustrative example to show that our construction methods differ from the known approaches and investigate the relationship between them. Furthermore, these methods are generalized by iteration to an ordinal sum construction for t-norms and t-conorms on a bounded lattice.

Some new versions of an old game

Vladimir Vladimirovich Tkachuk (1995)

Commentationes Mathematicae Universitatis Carolinae

The old game is the point-open one discovered independently by F. Galvin [7] and R. Telgársky [17]. Recall that it is played on a topological space X as follows: at the n -th move the first player picks a point x n X and the second responds with choosing an open U n x n . The game stops after ω moves and the first player wins if { U n : n ω } = X . Otherwise the victory is ascribed to the second player. In this paper we introduce and study the games θ and Ω . In θ the moves are made exactly as in the point-open game, but the...

Some notes on the category of fuzzy implications on bounded lattices

Amin Yousefi, Mashaallah Mashinchi, Radko Mesiar (2021)

Kybernetika

In this paper, we introduce the product, coproduct, equalizer and coequalizer notions on the category of fuzzy implications on a bounded lattice that results in the existence of the limit, pullback, colimit and pushout. Also isomorphism, monic and epic are introduced in this category. Then a subcategory of this category, called the skeleton, is studied. Where none of any two fuzzy implications are Φ -conjugate.

Some notes on U-partial order

M. Nesibe Kesicioğlu, Ü. Ertuğrul, F. Karaçal (2019)

Kybernetika

In this paper, an equivalence on the class of uninorms on a bounded lattice is discussed. Some relationships between the equivalence classes of uninorms and the equivalence classes of their underlying t-norms and t-conorms are presented. Also, a characterization for the sets admitting some incomparability w.r.t. the U-partial order is given.

Some properties concerning the quasi-inverse of a t-norm.

Dionís Boixader (1998)

Mathware and Soft Computing

Some properties of the quasi-inverse operators are presented. They are basic tools in order to reduce complex expressions involving several of such operators. An effective calculation for the quasi-inverse of a continuous t-norm is also provided.

Some properties of B -operations

Bohdan Butkiewicz (2007)

Kybernetika

In the paper the problem of mathematical properties of B -operations and weak W B -operations introduced by the author for interpretation of connectives “and”, “or”, and “also” in fuzzy rules is considered. In previous author’s papers some interesting properties of fuzzy systems with these operations were shown. These operations are weaker than triangular norms used commonly for a fuzzy system described by set of rules of the type if – then. Monotonicity condition, required for triangular norms, is...

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