Recursive coalgebras of finitary functors
For finitary set functors preserving inverse images, recursive coalgebras A of Paul Taylor are proved to be precisely those for which the system described by A always halts in finitely many steps.
Regularising natural dualities.
Relational structures and dependence spaces
Relative congruence distributivity within quasivarieties of nearly associative Φ-algebras
Remarks on quasivarieties of algebras
Representation of ordered classes by classes of connected unary algebras
Retract varieties of monounary algebras
Ring-like operations is pseudocomplemented semilattices
Ring-like operations are introduced in pseudocomplemented semilattices in such a way that in the case of Boolean pseudocomplemented semilattices one obtains the corresponding Boolean ring operations. Properties of these ring-like operations are derived and a characterization of Boolean pseudocomplemented semilattices in terms of these operations is given. Finally, ideals in the ring-like structures are defined and characterized.