Binary forms and orders of algebraic number fields.
For any Eichler order of level in an indefinite quaternion algebra of discriminant there is a Fuchsian group and a Shimura curve . We associate to a set of binary quadratic forms which have semi-integer quadratic coefficients, and we develop a classification theory, with respect to , for primitive forms contained in . In particular, the classification theory of primitive integral binary quadratic forms by is recovered. Explicit fundamental domains for allow the characterization...
Let , with a positive integer, be a pure cubic number field. We show that the elements whose squares have the form for rational numbers form a group isomorphic to the group of rational points on the elliptic curve . This result will allow us to construct unramified quadratic extensions of pure cubic number fields .
The aim of the paper is to present the binomial transformation formulae of Fibonacci numbers scaled by complex multipliers. Many of these new and nontrivial relations follow from the fundamental properties of the so-called delta-Fibonacci numbers defined by Wituła and Słota. The paper contains some original relations connecting the values of delta-Fibonacci numbers with the respective values of Chebyshev polynomials of the first and second kind.
We construct new birational maps between quadrics over a field. The maps apply to several types of quadratic forms, including Pfister neighbors, neighbors of multiples of a Pfister form, and half-neighbors. One application is to determine which quadrics over a field are ruled (that is, birational to the projective line times some variety) in a larger range of dimensions. We describe ruledness completely for quadratic forms of odd dimension at most 17, even dimension at most 10, or dimension 14....