IF YOU CAN SEE THIS go to http://www.cs.cornell.edu/Info/People/sfa/Nuprl/Shared/Xindentation_hack_doc.html
At:
one one corr 2 inversion A,B:Type. (A ~ B) (B ~ A)
By:
Def of Sym x,y:Type. x ~ y THEN BackThru: Thm* EquivRel X,Y:Type. X ~ Y
Generated subgoals:
None
About:
IF YOU CAN SEE THIS go to http://www.cs.cornell.edu/Info/People/sfa/Nuprl/Shared/Xindentation_hack_doc.html
A,B:Type. (A ~ B) 
(B ~ A)
Def of Sym x,y:Type. x ~ y THEN BackThru: Thm* EquivRel X,Y:Type. X ~ Y
