I am trying to solve the following context free grammar problem with hashtag approach but i can't figure it out. Can anyone help please?

Show a context-free grammar for the following languages: $$\{w\in\{a,b\}^*: \#_a(w)=2\#_b(w)\} $$

  • $\begingroup$ Can you explain what is hashtag approach? $\endgroup$ – John L. Dec 7 '18 at 11:37
  • $\begingroup$ The exercise has a hashtag and that's what is confusing me. $\endgroup$ – csandreas1 Dec 7 '18 at 11:43
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    $\begingroup$ $\#_a(w)$ probably means simply the number of "a"s in $w$... $\endgroup$ – dkaeae Dec 7 '18 at 13:09
  • $\begingroup$ Why do you copy-paste a grammar for the language $\{ a^ ib^ jc^k \mid i=j \text{ or } j=k\}$ in your question? $\endgroup$ – Hendrik Jan Dec 7 '18 at 18:49
  • $\begingroup$ My comment is irrelevant to the question, but what a veteran of formal grammar @HendrikJan is! $\endgroup$ – John L. Dec 7 '18 at 20:45

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