Given a Context-Free-Grammar the script will convert it into the selected Normal Form

[“形式语言与自动机”实验：给定任意上下文无关文法，将其转换为Greibach范式，再转换为NPDA，并能验证给定句子是否属于该文法。][Given an context-free grammar, convert it to Greibach paradigm, then to NPDA(i.e. Non-deterministic PushDown Automaton), and verify whether any sentence belongs to the grammar.]

In the theory of computation, a pushdown automaton (PDA) is a type of automaton that employs a stack. In this program, a PDA is going to be constructed by the input grammar.