Def unsolvable M.pre(a,s)
Def == P != 1of(2of(2of(2of(M))))(a) ==> v:M.da(locl(a)). P(s,v)

is mentioned

In prior sections: mb event system 5

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