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12:27 PM
@Raphael @Gilles Hello!!

I have to write an O(n^3) algorithm to determine whether a given string w=a_1 a_2 ... a_n is in L(G), where G=(N, Σ ,P, S) is a context-free grammar in Chomsky normal form.

Could you give me some hints how to do that??
 
 
5 hours later…
vzn
5:19 PM
MS chomsky normal form is a std form with a lot of known algorithms (going back decades). its nearly just a research question to go look up an efficient chomsky parser algorithm etc and some standard one will be O(n^3)... although a gifted student could probably figure out the algorithm by studying the chomsky normal form dynamics.
suggest you start by stating what is the input format.
re choosing areas of CS to specialize in, did you do any research or reading on that? curious what you found
it seems you did write out an "input form" for the problem above but it doesnt quite make sense to me.
its too generic.
 
6:11 PM
@vzn Could you maybe give me the general idea of such an algorithm??
 
 
2 hours later…
vzn
8:23 PM
MS you say you are a grad student. what about doing your hw? have you done any research on this problem or any other problem? "research" meaning simply, eg, a google search. you can try posting the question & will consider answering it although there are a bunch of other highrep users on here who are much more "FGITW"
what school are you going to? US or outside? what is your undergrad degree in? plz answer my questions if you want my personal help/ time/ attn
 
 
3 hours later…
11:34 PM
@vzn I am in an university outside, not in US. My undergrad degree is in applied mathematics.
 

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