Section: New Results
Managing Dynamic Linked Data
Complex Event Processing
In his PhD project , Sakho supervised by Niehren and Boneva proposes studies the complexity of answering automata queries on hyperstreams. A hyperstream is collections of streams that are connected with each other. The motivation for hyperstreams is to avoid blocking when composing of several stream processes. They show that the problem of deciding whether a tuple can is certain for selection on a hyperstream by query defined by finite automaton is Pspace -complete.
Symbolic tree transducers define transformations of data trees Adrien Boiret, Vincent Hugot and Joachim Niehren could show at at DLT  that the equivalence problem of symbolic top-down tree transducers can be reduced to that of standard top-down tree transducers. Thereby, the existing equivalence testers can be lifted to the symbolic tree transducers, yielding the algorithms needed for verification tasks in the ANR projec CoLiS. An implementation of such an algorithm by Nicolas Bacquey is on the way.
P. Gallot and S. Salvati presented their work on 1-register streaming string transducers at STACS . This work is a collaboration with University of Bordeaux. Streaming String Transducers have recently gained a growing interest since they can be used to model transformations on data streams. In this work, P. Gallot, S. Salvati and their co-authors prove that 1-register streaming string transducers can be decomposed as a finite union of functional transducers. An immediate corollary of this result is that the equivalence of such transducers is decidable, which means that we can check if two given transducers represent the same transformation on data streams.