theorem
  p |-| q implies All(x,p) |-| All(y,q)
proof
  assume
A1: p |-| q;
A2: q |-| All(y,q) by Th36;
  All(x,p) |-| p by Th36;
  then All(x,p) |-| q by A1,Th28;
  hence thesis by A2,Th28;
end;
