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Linguistic Perception
Published in Konar Amit, Artificial Intelligence and Soft Computing, 2018
A context free grammar G is generally defined by a 4 tuple, given by G = {Vn,Vt,S,P }, where Vn is a set of non-terminal symbols, Vt denotes a set of terminal symbols, S denotes the starting symbol and P represents a set of production rules that cause a change. It may further be noted that Vn ∪ Vt denotes the entire set of symbols. The above definition of context free grammar is prevalent in automata theory and compilers. The tuples in G are illustrated below with an example.
C
Published in Phillip A. Laplante, Dictionary of Computer Science, Engineering, and Technology, 2017
context-free grammar a phrase structure grammar that is a Type 2 grammar in the Chomsky hierarchy. Characterized by productions of the form N → x, where N is a member of the nonterminal symbols of the grammar and x is a sequence of zero or more symbols from the grammar’s vocabulary, V; that is, x can be defined as a member of V*, where * is the Kleene Star. See also pushdown automaton.
*
Published in K. S. Fu, Pattern Recognition, 2019
If each production in P is of the form A → α, where A is in N and α is in (NUΣ)*, then the grammar G is a context-free grammar. The set of languages generated by context-free grammars is called context-free languages.
Coding-theorem like behaviour and emergence of the universal distribution from resource-bounded algorithmic probability
Published in International Journal of Parallel, Emergent and Distributed Systems, 2019
Hector Zenil, Liliana Badillo, Santiago Hernández-Orozco, Francisco Hernández-Quiroz
As the results demonstrate (supported by Figure 5), by varying the allowed execution time for the space of Turing Machines we can approximate the CTM distribution corresponding to each level of the Chomsky hierarchy. For instance, regular languages (Type-3 grammars) can be decoded in linear time, given that each transition and state in a finite automaton can be encoded by a corresponding state and transition in a Turing Machine. Context-free grammars (Type-2) can be decoded in polynomial time with parsing algorithms such as CYK (Section 2.3.2).