theorem
  s/.2 = N-max L~s & s/.2 = E-max L~s
proof
  consider D such that
A1: s = SpStSeq D by Def2;
A2: s/.2 = NE-corner D by A1,Th36;
  hence s/.2 = N-max L~s by A1,Th77;
  thus thesis by A1,A2,Th79;
end;
