Foreward for special issue of philosophical magazine on: topological correlated insulators and SmB6

This Foreward briefly surveys the recent burst of research on the mixed valent insulator SmB6 in the context of two questions, (1) is SmB6 in fact the first example of a strongly correlated topological insulator, and (2) if so are there unique features of special interest for both topology and strong correlations? Accordingly, the papers of this special issue are situated within this general rubric.