cyk

How does the CYK algorithm work?

由 白昼怎懂夜的黑 提交于 2020-01-01 12:11:09
问题 I have to check if a string can be derived from a given context free that is in Chomsky normal form. I'm using C++. There is very nice pseudocode on the Wikipedia article covering the CYK algorithm, but I can't understand it very well. Would someone be so kind to help me out by giving me another pseudocode for CYK algorithm, or maybe explain the one in the wiki article? 回答1: The CYK algorithm takes as input a CFG that's in Chomsky normal form. That means that every production either has the

Equating a Sublist to Another Sublist for CYK table in Prolog

由 本小妞迷上赌 提交于 2019-12-24 01:58:33
问题 I'm currently working on a Prolog program that will generate a CYK parse table after being given a set of productions. However, I am having troubles checking two rows to see if they are equivalent. Here's what I have so far: answer(X,X). %Checks to see if it is equivalent equal(X,Y) :- sort(X,X1), sort(Y,Y1), X1 == Y1. %find the length of the lists total_length([],0). total_length([_|Xs],L) :- total_length(Xs,M), L is M+1. %storing length of lists and possible use of a decrement here to

Cannot understand CYK Algorithm pseudo-code

由 我的未来我决定 提交于 2019-12-10 14:55:48
问题 I was reading about the CYK algorithm, and there is one part of pseudo-code I cannot understand. The whole pseudo-code is: let the input be a string S consisting of n characters: a1 ... an. let the grammar contain r nonterminal symbols R1 ... Rr. This grammar contains the subset Rs which is the set of start symbols. let P[n,n,r] be an array of booleans. Initialize all elements of P to false. for each i = 1 to n for each unit production Rj -> ai set P[i,1,j] = true for each i = 2 to n --

Extract probabilities and most likely parse tree from cyk

由 回眸只為那壹抹淺笑 提交于 2019-12-08 13:50:37
问题 In order to understand cyk algorithm I've worked through example on : https://www.youtube.com/watch?v=VTH1k-xiswM&feature=youtu.be . The result of which is : How do I extract the probabilities associated with each parse and extract the most likely parse tree ? 回答1: These are two distinct problems for PCFG: recognition : does the sentence belong to the language generated by the CFG? (output: yes or no) parsing : what is the highest scoring tree for this sentence? (output: parse tree) The CKY

Steps to generate parse tree from CYK Algorithm (Natural Language Processing)

由 痴心易碎 提交于 2019-12-07 23:18:51
问题 I am currently working on a project involving NLP. I have implemented a CKY identifier as given in Jurafsky and Martin (algorithm on page 450). The table so produced actually stores the nonterminals in the table (instead of the usual boolean values). However, the only issue I am getting is to retrieve the parse tree. Here is an illustration of what my CKY identifier does: This is my grammar S -> NP VP S -> VP NP -> MODAL PRON | DET NP | NOUN VF | NOUN | DET NOUN | DET FILENAME MODAL -> 'MD'

Steps to generate parse tree from CYK Algorithm (Natural Language Processing)

由 夙愿已清 提交于 2019-12-06 07:12:23
I am currently working on a project involving NLP. I have implemented a CKY identifier as given in Jurafsky and Martin (algorithm on page 450). The table so produced actually stores the nonterminals in the table (instead of the usual boolean values). However, the only issue I am getting is to retrieve the parse tree. Here is an illustration of what my CKY identifier does: This is my grammar S -> NP VP S -> VP NP -> MODAL PRON | DET NP | NOUN VF | NOUN | DET NOUN | DET FILENAME MODAL -> 'MD' PRON -> 'PPSS' | 'PPO' VP -> VERB NP VP -> VERB VP VP -> ADVERB VP VP -> VF VERB -> 'VB' | 'VBN' NOUN ->
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