Q:

Do not understand NLTK Regex Parsing Format

I dont understand how does NLTK Regex Parsing Syntax works.  
Kindly see below.  
parser = RegexpParser('''
    NP: {<DT>?  <JJ>* <NN>*} # NP
    P: {<IN>}           # Preposition
    V: {<V.*>}          # Verb
    PP: {<P> <NP>}      # PP -> P NP
    VP: {<V> <NP|PP>*}  # VP -> V (NP|PP)*
    ''')

What does <DT>?  or * mean.  
Whats the difference between <V>.*  and <V.*> 
Thanks

A:

DT is a determiner like a,the ,...
Verb participle defintion - A participle (glossing abbreviation PTCP) is a form of a verb that is used in a sentence to modify a noun, noun phrase, verb, or verb phrase, and plays a role similar to an adjective or adverb. ...  It is one of the types of nonfinite verb forms. 
<V>.*  is for verb participle   example : drawn sword (drawn is vp)
<V.*> is a verb                example :going , go 

You can find more about them here :
https://www.ling.upenn.edu/courses/Fall_2003/ling001/penn_treebank_pos.html 
What does * mean ?   It's the same * that's used in regular expressions. *  denotes any set of characters (Ofcourse the set of characters that constitute the * should make sense upon combination)
Let's go into some examples - 
<V.*> A verb followed by anything in the same run like go(ing) mov(ing) 

