An infinite hierarchy of intersections of context-free languages
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- Liu, L.Y. & Weiner, P. Math. Systems Theory (1973) 7: 185. doi:10.1007/BF01762237
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The class of languages expressible as the intersection ofk context-free languages is shown to be properly contained within the class of languages expressible as the intersection ofk + 1 context-free languages. Hence an infinite hierarchy of classes of languages is exhibited between the class of context-sensitive languages and the class of context-free languages.