Ordered Tree-Pushdown Systems

Lorenzo Clemente, Pawel Parys, Sylvain Salvati, Igor Walukiewicz, Marc Herbstritt
2015 Foundations of Software Technology and Theoretical Computer Science  
We define a new class of pushdown systems where the pushdown is a tree instead of a word. We allow a limited form of lookahead on the pushdown conforming to a certain ordering restriction, and we show that the resulting class enjoys a decidable reachability problem. This follows from a preservation of recognizability result for the backward reachability relation of such systems. As an application, we show that our simple model can encode several formalisms generalizing pushdown systems, such as
more » ... ordered multi-pushdown systems, annotated higher-order pushdown systems, the Krivine machine, and ordered annotated multipushdown systems. In each case, our procedure yields tight complexity.
doi:10.4230/lipics.fsttcs.2015.163 dblp:conf/fsttcs/ClementePSW15 fatcat:nk3iigwctzbyfasttkojjjhxoa