is mentioned by

Thm* l:IdLnk, p:IdLnk List. Thm* lpath([l / p]) Thm*  Thm* lpath(p) Thm* & (||p|| = 0    destination(l) = source(hd(p)) & hd(p) = lnk-inv(l))	[lpath_cons]
Thm* l:IdLnk. destination(lnk-inv(l)) = source(l)	[ldst-inv]
Thm* l:IdLnk. source(lnk-inv(l)) = destination(l)	[lsrc-inv]
Def lpath(p) Def == i:(||p||-1).  Def == destination(p[i]) = source(p[(i+1)]) & p[(i+1)] = lnk-inv(p[i])  IdLnk	[lpath]

In prior sections: mb event system 1

Try larger context: EventSystems IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html