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#################################################################
# #
# README file for evalb #
# #
# Satoshi Sekine (NYU) #
# Mike Collins (UPenn) #
# #
# October.1997 #
#################################################################
Contents of this README:
[0] COPYRIGHT
[1] INTRODUCTION
[2] INSTALLATION AND RUN
[3] OPTIONS
[4] OUTPUT FORMAT FROM THE SCORER
[5] HOW TO CREATE A GOLDFILE FROM THE TREEBANK
[6] THE PARAMETER FILE
[7] MORE DETAILS ABOUT THE SCORING ALGORITHM
[0] COPYRIGHT
The authors abandon the copyright of this program. Everyone is
permitted to copy and distribute the program or a portion of the program
with no charge and no restrictions unless it is harmful to someone.
However, the authors are delightful for the user's kindness of proper
usage and letting the authors know bugs or problems.
This software is provided "AS IS", and the authors make no warranties,
express or implied.
[1] INTRODUCTION
Evaluation of bracketing looks simple, but in fact, there are minor
differences from system to system. This is a program to parametarize
such minor differences and to give an informative result.
"evalb" evaluates bracketing accuracy in a test-file against a gold-file.
It returns recall, precision, tagging accuracy. It uses an identical
algorithm to that used in (Collins ACL97).
[2] Installation and Run
To compile the scorer, type
> make
To run the scorer:
> evalb -p Parameter_file Gold_file Test_file
For example to use the sample files:
> evalb -p sample.prm sample.gld sample.tst
[3] OPTIONS
You can specify system parameters in the command line options.
Other options concerning to evaluation metrix should be specified
in parameter file, described later.
-p param_file parameter file
-d debug mode
-e n number of error to kill (default=10)
-h help
[4] OUTPUT FORMAT FROM THE SCORER
The scorer gives individual scores for each sentence, for
example:
Sent. Matched Bracket Cross Correct Tag
ID Len. Stat. Recal Prec. Bracket gold test Bracket Words Tags Accracy
============================================================================
1 8 0 100.00 100.00 5 5 5 0 6 5 83.33
At the end of the output the === Summary === section gives statistics
for all sentences, and for sentences <=40 words in length. The summary
contains the following information:
i) Number of sentences -- total number of sentences.
ii) Number of Error/Skip sentences -- should both be 0 if there is no
problem with the parsed/gold files.
iii) Number of valid sentences = Number of sentences - Number of Error/Skip
sentences
iv) Bracketing recall = (number of correct constituents)
----------------------------------------
(number of constituents in the goldfile)
v) Bracketing precision = (number of correct constituents)
----------------------------------------
(number of constituents in the parsed file)
vi) Complete match = percentaage of sentences where recall and precision are
both 100%.
vii) Average crossing = (number of constituents crossing a goldfile constituen
----------------------------------------------------
(number of sentences)
viii) No crossing = percentage of sentences which have 0 crossing brackets.
ix) 2 or less crossing = percentage of sentences which have <=2 crossing brackets.
x) Tagging accuracy = percentage of correct POS tags (but see [5].3 for exact
details of what is counted).
[5] HOW TO CREATE A GOLDFILE FROM THE PENN TREEBANK
The gold and parsed files are in a format similar to this:
(TOP (S (INTJ (RB No)) (, ,) (NP (PRP it)) (VP (VBD was) (RB n't) (NP (NNP Black) (NNP Monday))) (. .)))
To create a gold file from the treebank:
tgrep -wn '/.*/' | tgrep_proc.prl
will produce a goldfile in the required format. ("tgrep -wn '/.*/'" prints
parse trees, "tgrep_process.prl" just skips blank lines).
For example, to produce a goldfile for section 23 of the treebank:
tgrep -wn '/.*/' | tail +90895 | tgrep_process.prl | sed 2416q > sec23.gold
[6] THE PARAMETER (.prm) FILE
The .prm file sets options regarding the scoring method. COLLINS.prm gives
the same scoring behaviour as the scorer used in (Collins 97). The options
chosen were:
1) LABELED 1
to give labelled precision/recall figures, i.e. a constituent must have the
same span *and* label as a constituent in the goldfile.
2) DELETE_LABEL TOP
Don't count the "TOP" label (which is always given in the output of tgrep)
when scoring.
3) DELETE_LABEL -NONE-
Remove traces (and all constituents which dominate nothing but traces) when
scoring. For example
.... (VP (VBD reported) (SBAR (-NONE- 0) (S (-NONE- *T*-1)))) (. .)))
would be processed to give
.... (VP (VBD reported)) (. .)))
4)
DELETE_LABEL , -- for the purposes of scoring remove punctuation
DELETE_LABEL :
DELETE_LABEL ``
DELETE_LABEL ''
DELETE_LABEL .
5) DELETE_LABEL_FOR_LENGTH -NONE- -- don't include traces when calculating
the length of a sentence (important
when classifying a sentence as <=40
words or >40 words)
6) EQ_LABEL ADVP PRT
Count ADVP and PRT as being the same label when scoring.
[7] MORE DETAILS ABOUT THE SCORING ALGORITHM
1) The scorer initially processes the files to remove all nodes specified
by DELETE_LABEL in the .prm file. It also recursively removes nodes which
dominate nothing due to all their children being removed. For example, if
-NONE- is specified as a label to be deleted,
.... (VP (VBD reported) (SBAR (-NONE- 0) (S (-NONE- *T*-1)))) (. .)))
would be processed to give
.... (VP (VBD reported)) (. .)))
2) The scorer also removes all functional tags attached to non-terminals
(functional tags are prefixed with "-" or "=" in the treebank). For example
"NP-SBJ" is processed to give "NP", "NP=2" is changed to "NP".
3) Tagging accuracy counts tags for all words *except* any tags which are
deleted by a DELETE_LABEL specification in the .prm file. (For example, for
COLLINS.prm, punctuation tagged as "," ":" etc. would not be included).
4) When calculating the length of a sentence, all words with POS tags not
included in the "DELETE_LABEL_FOR_LENGTH" list in the .prm file are
counted. (For COLLINS.prm, only "-NONE-" is specified in this list, so
traces are removed before calculating the length of the sentence).
5) There are some subtleties in scoring when either the goldfile or parsed
file contains multiple constituents for the same span which have the same
non-terminal label. e.g. (NP (NP the man)) If the goldfile contains n
constituents for the same span, and the parsed file contains m constituents
with that nonterminal, the scorer works as follows:
i) If m>n, then the precision is n/m, recall is 100%
ii) If n>m, then the precision is 100%, recall is m/n.
iii) If n==m, recall and precision are both 100%.
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