On the semigroup of binary relations on a finite set
On the semigroup of fully indecomposable relations
On tolerance analysis
On types of fuzzy numbers under addition
We consider the question whether, for given fuzzy numbers, there are different pairs of -norm such that the resulting membership function within the extension principle under addition are identical. Some examples are given.
Operations, homomorphism and update versus relational database systems
Ordering D-classes and computing Schein rank is hard.
Ordinal ultrafilters versus P-hierarchy
An earlier paper [Starosolski A., P-hierarchy on βω, J. Symbolic Logic, 2008, 73(4), 1202–1214] investigated the relations between ordinal ultrafilters and the so-called P-hierarchy. The present paper focuses on the aspects of characterization of classes of ultrafilters of finite index, existence, generic existence and the Rudin-Keisler-order.