[mizar] copy/paste detection in MML

[Josef Urban <urban@ktilinux.ms.mff.cuni.cz>]

Hi,

at http://lipa.ms.mff.cuni.cz/~urban/mmlcpd/mmlcpd.4.87.985/cpd/ are 
results of running the CPD (Copy/paste Detector, 
http://pmd.sourceforge.net/cpd.html) on each MML article. About four 
thousands copied blocks were detected, use 
http://lipa.ms.mff.cuni.cz/~urban/mmlcpd/mmlcpd.4.87.985/cpd/?C=S;O=D to 
sort the articles by their amount of copying.

I'll probably also add info about inter-article copying later. The 
detection could be also improved by writing a special Mizar parser for 
CPD, and using normalized versions of articles (e.g. with normalized 
identifier names - could be done by simple postprocessing of the XML 
representation).

I hope this info will be used to gradually get rid of the worst copyings. 
I also suggest to use tools like CPD as a part of the reviewing process 
for MML articles.

Best,
Josef Urban