public static ProbContextFreeGrammar buildWumpusGrammar()
{
ProbContextFreeGrammar g = new ProbContextFreeGrammar();
ICollection <Rule> rules = CollectionFactory.CreateQueue <Rule>();
// Start Rules
rules.Add(new Rule("S", "NP,VP", (float)0.90));
rules.Add(new Rule("S", "CONJ,S", (float)0.10));
// Noun Phrase Rules
rules.Add(new Rule("NP", "PRONOUN", (float)0.30));
rules.Add(new Rule("NP", "NAME", (float)0.10));
rules.Add(new Rule("NP", "NOUN", (float)0.10));
rules.Add(new Rule("NP", "ARTICLE,NOUN", (float)0.25));
rules.Add(new Rule("NP", "AP,NOUN", (float)0.05));
rules.Add(new Rule("NP", "DIGIT,DIGIT", (float)0.05));
rules.Add(new Rule("NP", "NP,PP", (float)0.10));
rules.Add(new Rule("NP", "NP,RELCLAUSE", (float)0.05));
// add verb phrase rules
rules.Add(new Rule("VP", "VERB", (float)0.40));
rules.Add(new Rule("VP", "VP,NP", (float)0.35));
rules.Add(new Rule("VP", "VP,ADJS", (float)0.05));
rules.Add(new Rule("VP", "VP,PP", (float)0.10));
rules.Add(new Rule("VP", "VP,ADVERB", (float)0.10));
// add adjective rules
rules.Add(new Rule("AJD", "AJDS", (float)0.80));
rules.Add(new Rule("AJD", "AJD,AJDS", (float)0.20));
// add Article Phrase
// This deviates from the text because the text provides the rule:
// NP -> Article Adjs Noun, which is NOT in Chomsky Normal Form
//
// We instead define AP (Article Phrase) AP -> Article Adjs, to get around this
rules.Add(new Rule("AP", "ARTICLE,ADJS", (float)1.0));
// add preposition phrase
rules.Add(new Rule("PP", "PREP,NP", (float)1.00));
// add relative clause
rules.Add(new Rule("RELCLAUSE", "RELPRO,VP", (float)1.00));
// Now we can add all rules that derive terminal symbols, which are in
// this case words.
Lexicon wumpusLex = LexiconExamples.buildWumpusLex();
ICollection <Rule> terminalRules = CollectionFactory.CreateQueue <Rule>(wumpusLex.getAllTerminalRules());
rules.AddAll(terminalRules);
// Add all these rules into the grammar
if (!g.addRules(rules))
{
return(null);
}
return(g);
}
/**
* A more restrictive phrase-structure grammar, used in testing and demonstrating
* the CYK Algorithm.
* Note: It is complemented by the "trivial lexicon" in LexiconExamples.java
* @return
*/
public static ProbCNFGrammar buildTrivialGrammar()
{
ProbCNFGrammar g = new ProbCNFGrammar();
ICollection <Rule> rules = CollectionFactory.CreateQueue <Rule>();
rules.Add(new Rule("S", "NP,VP", (float)1.0));
rules.Add(new Rule("NP", "ARTICLE,NOUN", (float)0.50));
rules.Add(new Rule("NP", "PRONOUN,ADVERB", (float)0.5));
rules.Add(new Rule("VP", "VERB,NP", (float)1.0));
// add terminal rules
Lexicon trivLex = LexiconExamples.buildTrivialLexicon();
ICollection <Rule> terminalRules = CollectionFactory.CreateQueue <Rule>(trivLex.getAllTerminalRules());
rules.AddAll(terminalRules);
// Add all these rules into the grammar
if (!g.addRules(rules))
{
return(null);
}
return(g);
}
public void setUp()
{
l = new Lexicon();
wumpusLex = LexiconExamples.buildWumpusLex();
}
