The rational filling radius of complex projective space (Q1183661)

In this paper the author computes the filling radius with rational coefficients of the complex projective \(n\)-space as \({1\over 2} \arccos(- {1\over 3})\) by a straightforward homological calculation using the Serre-spectral sequence and the Schubert calculus. He also computes the integer filling radius of the complex projective 2-space as \({1\over 2}\arccos(-{1\over 3})\) again and exhibits a torsion obstruction to filling complex projective 3-space.