>python cky.py --h
usage: cky.py [-h] [--ntrules NT_RULES] [--trules T_RULES] [--output OUTPUT]
              [--start_symbol START_SYMBOL] [--sentences SENTENCES]

Script which implements the Cocke-Younger-Kasami parsing algorithm with
probabilistic rules.

optional arguments:
  -h, --help            show this help message and exit
  --nt_rules NT_RULES   name of file with non-terminating rules
  --t_rules T_RULES     name of file with terminating rules of form
  --output OUTPUT       name of output-file (prints to stdout if not
                        specified)
  --start_symbol START_SYMBOL
                        Start-symbol in Grammar
  --sentences SENTENCES
                        name of file with sentences (new line after each
                        sentence)
                        
Non-terminal rules represent rules where one non-terminal creates at least one new non-terminal, i.e. rules of format:
A -> B
A -> B C 
A -> A A
A -> B A
A -> A B
with non-terminals {A, B, C}.

Terminal rules represent rules where one non-terminal creates exactly one terminal, i.e. rules of format:
A -> a
with non-terminal A and terminal a.

Format for specifying rules (new line after each rule):
[probability] [producer] [produced]
[probability] [producer] [produced] [produced]

e.g. non-terminal:
1.0	S	NP	VP
0.1 NP	Pron

e.g. terminal:
0.4	Pron	I