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2. Simultaneous similarity of tuples of matrices over C. Problem 1 is notoriously difficult. We show that for the local ring H0 this problem reduces to a Problem 2 for certain kind of matrices. We then discuss certain special cases of Problem 2 as simultaneous similarity of tuples of matrices to upper triangular and diagonal matrices. L-property of pairs of matrices, that discussed next, is clo...

It is proved that the following conditions are equivalent: (a) there exists a complete, atomless, σ–centered Boolean algebra, which does not contain any regular, atomless, countable subalgebra, (b) there exists a nowhere dense ultrafilter on ω. Therefore the existence of such algebras is undecidable in ZFC. In ”forcing language” condition (a) says that there exists a non– trivial σ–centered for...

Starting with a σ-finite measure on an algebra, we define a pseudometric and show how measurable sets from the Caratheodory Extension Theorem can be thought of as limit points of Cauchy sequences in the algebra.