We introduce the notion of diagonal ranks of semigroups, which are numerical characteristics of semigroups. Some base properties of diagonal ranks are obtained. A new criterion for a monoid being a group is obtained using diagonal ranks. For some semigroup classes we investigate whether their diagonal acts are finitely generated or not. For the semigroups of full transformations, partial transf...

OBJECTIVE To review the evidence on the efficacy of different types of existential therapies: a family of psychological interventions that draw on themes from existential philosophy to help clients address such issues in their lives as meaning and death anxiety. METHOD Relevant electronic databases, journals, and reference lists were searched for eligible studies. Effects on meaning, psychopa...

We propose an ownership types system with existential quantification of owners, similar to the existential quantification of types in models of Java wildcards. This produces a system with variant ownership types. Using explicit existential types for variance is more expressive, less ad hoc, and easier to understand and reason about than previous solutions. Furthermore, we propose using both typ...

We investigate a SAT-based bounded model checking (BMC) method for EMTLK (the existential fragment of the metric temporal logic with knowledge) that is interpreted over timed models generated by timed interpreted systems. In particular, we translate the existential model checking problem for EMTLK to the existential model checking problem for a linear temporal logic (called HLTLK), and we provi...