Universality for Context-Free Grammars is Undecidable
Here we show that the "universality" problem for context-free grammars is undecidable. It is similar to the E_LBA video but we instead embed strings NOT enco...
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About this video
Here we show that the "universality" problem for context-free grammars is undecidable. It is similar to the E_LBA video but we instead embed strings NOT encoding "reversed" accepting computation histories into the CFG.
What is a context-free grammar? It is a set of 4 items: a set of "variables," a set of "terminals," a "start variable," and a set of rules. Each rule must involve a single variable on its "left side", and any combination of variables and terminals on its right side. See https://www.youtube.com/watch?v=h1OSmLSacNA&ab_channel=EasyTheory for more details.
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Jan 20, 2021
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#easy theory #allcfg undecidable #all_cfg undecidable #undecidable #undecidable problems #undecidable problems about turing machine #undecidable language example #easy theory pumping lemma #easy theory turing machine #easy theory pushdown automata #allcfg #all_cfg #all cfg #undecidable problems in toc #undecidable language #easy theory undecidable
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