[mizar] PVS GPLed

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

Hi,

I just noted that PVS has been licensed under GPL since Dec 2006: 
http://pvs.csl.sri.com/mail-archive/pvs-announce/msg00007.html .

Mizar is thus the last major proof assistant whose sources are closed, and 
licensing unclear.

Josef