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Ở đây có ai có cuốn "Diferential Topology " from John W. Milnor không, share cho mình với.

With Love!

Let P be a finite projective plane of order k. Define < by p<l for a point p and a line l iff p l.

Add a least element below all the points and a greatest element above all the lines. Show that the result is a lattice L.