Building Logic Toolboxes Juan Heguiabehere Abstract: The last few years have seen a huge increase in the efficiency of theorem provers for modal and modal-like logics, and together with it the field of evaluation of these theorem provers has matured considerably. We will see some of the strategies used to develop automatic reasoning tools for these logics, and the role of empirical evaluation in this process. We will also see how Dynamic Predicate Logic (DPL) can be interpreted as a programming language, and how programs written in that language can be easily subjected to formal verification. Finally, we will see how automated reasoning can actually be used as a computation engine. This work is, then, about tools: their development, evaluation, and possible uses. Keywords: modal logic, automated reasonoing, dynamic predicate logic