The circle method and pairs of quadratic forms
We give non-trivial upper bounds for the number of integral solutions, of given size, of a system of two quadratic form equations in five variables.
The Lefschetz number of an involution on the space of classes of positive definite quadratic forms.
The level of real projective spaces.
The reduced Wittring
The u-invariant of fields with 16 and 32 square classes I
We discuss here the conjectures of Kaplansky and of Lam concerning the ii-univariant of a field of characteristic different from two. Both conjectures are shown t.o hold true for any field having at most 32 square classes.
Théorème sur les formes quadratiques