theorem Th24:
  not p on K & not p on L & x on K & x on L implies IncProj (K,p,L ).x=x
proof
A1: ex A st p on A & x on A by INCPROJ:def 5;
  assume ( not p on K)& not p on L & x on K & x on L;
  hence thesis by A1,Def1;
end;
