Emptiness Problems of eNCE Graph Languages

摘要

We consider the complexity of the emptiness problem for various classes of graph languages defined by eNCE (edge label neighborhood controlled embedding) graph grammars. In particular, we show that the emptiness problem is undecidable for general eNCE graph grammars, DEXPTIME-complete for confluent and boundary eNCE graph grammars, PSPACE-complete for linear eNCE graph grammars, NL-complete for deterministic confluent, deterministic boundary, and deterministic linear eNCE graph grammars. The exponential time algorithm for deciding emptiness of confluent eNCE graph grammars is based on an exponential time transformation of a confluent eNCE graph grammar into a nonblocking confluent eNCE graph grammar generating the same language.