theorem
  s/.1 = N-min L~s & s/.1 = W-max L~s
proof
  consider D such that
A1: s = SpStSeq D by Def2;
A2: s/.1 = NW-corner D by A1,Th35;
  hence s/.1 = N-min L~s by A1,Th76;
  thus thesis by A1,A2,Th75;
end;
