Pumping Lemma for CFG - If L is a context-free language, there is a pumping length p such that any string w ? L of length ? p can be written as w = uvxyz, where vy ? ?, |vxy| ? p, and for all i ? 0, uvixyiz ? L.
T,P,S)语法分析树，并且该树的产物为终结符ω。如果最长的路径长度为n，则|ω|≤2n−1 ...
we show that a pumping lemma for a class of languagesCCcan be used to study the computational complexity of the predicate “∈CC” via highly efficient many-one reductions. In this paper, we use extended regular expressions (EXREGs, introduced in Câmpeanu et al...