The group of (integral) automorphs of a ternary integral quadratic form f acts properly discontinuously as a group of isometries of the Riemann’s sphere (resp. the hyperbolic plane) if f is definite (resp. indefinite) and the quotient has a natural structure of spherical (resp. hyperbolic) orbifold, denoted by Qf\documentclass[12pt]{minimal}
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\begin{document}$$Q_{f}$$\end{document}. Then fis aB-covering of the formg if Qf\documentclass[12pt]{minimal}
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\begin{document}$$Q_{f}$$\end{document} is an orbifold covering of Qg\documentclass[12pt]{minimal}
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\begin{document}$$Q_{g}$$\end{document}, induced by T′fT=ρg\documentclass[12pt]{minimal}
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\begin{document}$$\begin{aligned} T^{\prime }fT=\rho g \end{aligned}$$\end{document}where T is an integral matrix and ρ>0\documentclass[12pt]{minimal}
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\begin{document}$$\rho >0$$\end{document} is an integer. Given an integral ternary quadratic form f a number Πf\documentclass[12pt]{minimal}
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\begin{document}$$\Pi _{f}$$\end{document}, called the B-invariant of the form f, is defined. It is conjectured that if f is a B-covering of the form g then both forms have the same B-invariant. The purpose of this paper is to reduce this conjecture to the case in which g is a form with square-free determinant. This reduction is based in the following main Theorem. Any definite (resp. indefinite) formfis aB-covering of a, unique up to genus (resp. integral equivalence), formgwith square-free determinant such thatfandghave the sameB-invariant. To prove this, a normal form of any definite (resp. indefinite) integral, ternary quadratic form f is introduced. Some examples and open questions are given.
