On the computational power of context-free PC grammar systems

On the Degree Complexity of Special Non-Context-Free Languages with Respect to PC Grammar Systems

When modeling natural languages, three languages are of special interest. In natural languages, there occur phenomena like multiple agreements, crossed agreements and replication. These aspects are represented by the three languages K1 = {abc |n ≥ 1}, K2 = {abcd |m,n ≥ 1} and K3 = {ww |w ∈ {a, b}}, respectively. In the present paper, we give parallel communicating grammar systems (PC grammar sy...

On the Size Complexity of Non-Returning Context-Free PC Grammar Systems

Improving the previously known best bound, we show that any recursively enumerable language can be generated with a non-returning parallel communicating (PC) grammar system having six contextfree components. We also present a non-returning universal PC grammar system generating unary languages, that is, a system where not only the number of components, but also the number of productions and the...

On the Computational Completeness of Context-Free Parallel Communicating Grammar Systems

We prove that all recursively enumerable languages can be generated by context-free returning parallel communicating grammar systems by showing how the parallel communicating grammars can simulate two-counter machines, a class of Turing machine variants which is known to be computationally complete. Moreover, we prove that systems with a bounded number of components are suucient to reach this g...

Studying impressive parameters on the performance of Persian probabilistic context free grammar parser

In linguistics, a tree bank is a parsed text corpus that annotates syntactic or semantic sentence structure. The exploitation of tree bank data has been important ever since the first large-scale tree bank, The Penn Treebank, was published. However, although originating in computational linguistics, the value of tree bank is becoming more widely appreciated in linguistics research as a whole. F...

PC grammar systems with five context-free components generate all recursively enumerable languages