Claudia Chiriţă
University of Bucharest, Bucharest, Romania

Goguen and Burstall's institution theory has reshaped areas such as model theory and formal specification by providing category-theoretic abstractions of concepts from mathematical logic. One of the main advantages of this approach is that it declutters the workspace by allowing us to study logical phenomena unhindered by unnecessary details: many results in institution theory are agnostic to the structure of sentences or models. But this kind of abstraction is sometimes excessive when we want to illuminate specific features of logics, and calls for extensions of the original notion of institution. For example, stratified institutions recover local satisfaction as in possible-world semantics, capturing a wide class of modal logics. We continue this line of work by introducing an abstract concept of selection of connectives to deal with syntax in a modular manner, arriving at an intermediate level between concrete logics and institutions. To illustrate its use, we show how logics with typed modalities can be obtained through combinations of connectives.