Idempotent generated algebras and Boolean pairs
The maximal column rank of an m by n matrix is the maximal number of the columns of A which are linearly independent. We compare the maximal column rank with rank of matrices over a nonbinary Boolean algebra. We also characterize the linear operators which preserve the maximal column ranks of matrices over nonbinary Boolean algebra.
We study free sequences and related notions on Boolean algebras. A free sequence on a BA is a sequence of elements of , with an ordinal, such that for all with we have . A free sequence of length exists iff the Stone space has a free sequence of length in the topological sense. A free sequence is maximal iff it cannot be extended at the end to a longer free sequence. The main notions studied here are the spectrum function and the associated min-max function Among the results...
Let τ be a type of algebras without nullary fundamental operation symbols. We call an identity φ ≈ ψ of type τ clone compatible if φ and ψ are the same variable or the sets of fundamental operation symbols in φ and ψ are nonempty and identical. For a variety of type τ we denote by the variety of type τ defined by all clone compatible identities from Id(). We call the clone extension of . In this paper we describe algebras and minimal generics of all subvarieties of , where is the variety of...
We introduce a very weak version of the square principle which may hold even under failure of the generalized continuum hypothesis. Under this weak square principle, we give a new characterization (Theorem 10) of partial orderings with κ-Freese-Nation property (see below for the definition). The characterization is not a ZFC theorem: assuming Chang’s Conjecture for , we can find a counter-example to the characterization (Theorem 12). We then show that, in the model obtained by adding Cohen reals,...