Dynamic semantics as a compositional alternative for the representational framework of discourse representation theory originated in the late 1980's, early 1990's. Several joint papers with Jeroen Groenendijk and Frank Veltman on both theoretical and applied issues in this area are available in the Papers section.
The work with Jeroen Groenendijk on questions goes back to our joint dissertation of 1984, Studies on the Semantic of Questions and the Pragmatics of Answers, which is available as a (searchable) pdf. Partitioning Logical Space, the annotated Leuven handout from 1991, gives a reasonably comprehensive overview of the work. Along with several other papers on questions both are available in the Papers section.
Check out the "Inquisitive Semantics" site for recent work by Jeroen Groenendijk and associates.
Work here deals with the relationship between philosophical theories of interpretation (radical interpretation à la Quine and Davidson, but also the hermeneutics of Heidegger and Gadamer and the "practical" approach of Wittgenstein's later work) and various theories of formal semantics (classical Montague grammar, discourse representation theory, dynamic semantics), and with conceptual and methodological issues in formal semantics, such as compositionality, grammatical and logical form, and semantic competence. Cf., the material in the Papers section.
Wittgenstein has been an ongoing interest, in particular the contents of his ethical and religious views and their ontological and epistemological status. In 2002 World and Life as One. Ethics and Ontology in Wittgenstein's Early Thought, appeared with Stanford University Press. Currently the main focus is on the relationship between values and realism in the later work, in particular On Certainty. Cf., the Papers section for material on various issues concerning Wittgenstein's work.