Talk:Elliptic complex

What's sigma(Pi) ?
what are sigma(Pi) ? — Preceding unsigned comment added by 86.170.58.71 (talk) 09:19, 22 April 2012 (UTC)
 * Symbol of a differential operator was linked even back when this was posted. User:1234qwer1234qwer4 (talk) 13:30, 25 December 2021 (UTC)