This book on theoretical linguistics is perceived as a kind of Platonic dialogue between two conceptual frameworks, that of post-Montagovian formal semantics, represented by P., and Prague School linguistics, represented by H. and S, in which the participants work towards a synthesis. Examining the relation between tripartite structures and topic-focus articulation (TFA), they for instance conclude that embedded TFA happens only if there is an embedded clause and withold the idea that the counterpart of the focalizer is the operator, that of its background the restrictor and that of its focus the nuclear scope.