Rational Surface
where n is 0 for the projective plane, and 1 for Hirzebruch surfaces and greater than 1 for other rational surfaces.
The Picard group is the odd unimodular lattice I1,n, except for the Hirzebruch surfaces Σ2m when it is the even unimodular lattice II1,1.
Read more about Rational Surface: Castelnuovo's Theorem, Examples of Rational Surfaces
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