3 ms·
It has been formally verified: http://us.metamath.org/mpegif/canth2.html http://us.metamath.org/mpegif/canth2.html So, if you don't accept the proof, you have
by dooglius 8y ago
It has been formally verified: http://us.metamath.org/mpegif/canth2.html http://us.metamath.org/mpegif/canth2.html
So, if you don't accept the proof, you have to reject some axiom used. Which one do you have a problem with?