reserve AFV for WeakAffVect;
reserve a,b,c,d,e,f,a9,b9,c9,d9,f9,p,q,r,o,x99 for Element of AFV;

theorem Th32:
  a,b // PSym(p,b),PSym(p,a)
proof
  Mid a,p,PSym(p,a) & Mid b,p,PSym(p,b) by Def4;
  hence thesis by Th25;
end;
