This is a survey paper on various weak systems of Feferman’s explicit mathematics and their proof theory. The strength of the systems considered in measured in terms of their provably terminating operations typically belonging to some natural classes of computational time or space complexity.

We investigate with German data how the use of temporary agency work has helped establishments to manage the economic and financial crisis in 2008/09. We examine the (regular) workforce development, use of short-time work, and business performance of establishments that made differential use of temporary agency work prior to the crisis. Overall, our results suggest that establishments with a gr...

Scanning recent news sources, anyone preparing for the upcoming celebration of Christmas might wonder how exactly we can manage to celebrate wholeheartedly in a global climate of terrorist attacks, massive migrations of traumatized war victims and economic refugees, and generalized fear for the future. Commentators, syndicated columnists and political cartoonists in recent times have highlighte...

In Spescha and Strahm [15], a system PET of explicit mathematics in the style of Feferman [7, 8] is introduced, and in Spescha and Strahm [16] the addition of the join principle to PET is studied. Changing to intuitionistic logic, it could be shown that the provably terminating operations of PETJ are the polytime functions on binary words. However, although strongly conjectured, it remained ope...

The development of the infrastructure for ubiquitous computing is progressing rapidly, yet the applications that will be built on this new infrastructure remain largely ill defined. What will we do with these emerging capabilities? Stock quotes in 3-D on your heads-up display? Sports scores in stereo sound? We believe that the new kinds of services will result from three primary capabilities of...