Barwise and Perry's system was a top-down approach which foundered on practical issues which were early identified by Angelika Kratzer and others. She subsequently developed a considerable body of theory bottom-up by addressing a variety of issues in the areas of context dependency in discourse and the syntax–semantics interface.[4] Because of its practical nature and ongoing development this body of work "with possible situations as parts of possible worlds, now has much more influence than Barwise and Perry’s ideas".[5]