MathOverflow will be down for maintenance for approximately 3 hours, starting Monday evening (06/24/2013) at approximately 9:00 PM Eastern time (UTC-4).
    Post Made Community Wiki by Scott Morrison
show/hide this revision's text 1

The Noncommutative Torus in non-commutative geometry. (Maybe it has just shaped the subject because it is about the only thing one can handle explicitly)