We consider n 9 n matrix whose elements are fuzzy numbers (hereinafter a fuzzy matrix) and we introduce notions of regularity of a fuzzy matrix and the inverse matrix of a fuzzy matrix (hereinafter the fuzzy inverse) in this paper. It is shown that the fuzzy inverse is a fuzzy matrix as well. Also we pay attention to the calculation of the fuzzy inverse in a special case. Main results are based on Rohn's results in the field of linear problems with inexact data.

The paper is devoted to a concept of aggregation of binary fuzzy relations. Consider two n-ary vectors, when we know the degrees to which corresponding components are in relation we can measure the degree to which vectors are in relation. Tasks with such background justify the necessity of aggregation of binary fuzzy relations and we contribute to the topic in this paper. First we recall the approach previously appeared in literature and then we introduce other approaches suitable for various practical applications. Later we study the property of T -transitivity since it indicates in some sense the consistency of aggregation.

Abstract. We explore questions related to the aggregation operators and aggregation of fuzzy sets. No preliminary knowledge of the aggregation operators theory and of the fuzzy sets theory are required, because all necessary information is given in Section 2. Later we introduce a new class of γ-aggregation operators, which "ignore" arguments less than γ. Due to this property γ-aggregation operators simplify the aggregation process and extend the area of possible applications. The second part of the paper is devoted to the generalized aggregation problem. We use the definition of generalized aggregation operator, introduced by A. Takaci in [7], and study the pointwise extension of a γ-agop.