Commutative Derivation Context-free Language
The concepts of commutative derivation context-free grammar and of commutative derivation context-free language are presented. It is proofed that regular language and bound context-free language is a subset of the commutative derivation context-free language,while the commutative derivation context-free language is the subset of context-free language.The expression of commutative derivation context-free language is defined,and it is proofed that commutative derivation context-free grammar is equipollence with the expression of commutative derivation context-free language.