reserve x for set,
  p,q,r,s,t,u for ExtReal,
  g for Real,
  a for Element of ExtREAL;

theorem :: MEASURE5:28
  r <= p & r < s implies not [.r,s.[ c= ].p,q.[
proof
  assume that
A1: r <= p and
A2: r < s;
  take r;
  thus r in [.r,s.[ by A2,Th3;
  thus thesis by A1,Th4;
end;
