2 citations · 2 across the 2 of their papers we have counts for
4 papers
Determinantal quartic surfaces with a definite Hermitian representation
Martin Helsø
We give a bound on the number of isolated, essential singularities of determinantal quartic surfaces in 3-space. We also provide examples of different configurations of real singul…
Maximality of quartic symmetroids with a double quadric of codimension 1
Martin Helsø
We prove that the dimension of a quartic symmetroid singular along a quadric of codimension 1 is at most 4, if it is not a cone. In the maximal case, the quadric is reducible and c…
Rational Quartic Spectrahedra
Martin Helsø, Kristian Ranestad
Rational quartic spectrahedra in 3-space are semialgebraic convex subsets in of semidefinite, real symmetric -matrices, whose boundary admits a rationa…
Rational Quartic Symmetroids
Martin Helsø
We classify rational, irreducible quartic symmetroids in projective 3-space. They are either singular along a line or a smooth conic section, or they have a triple point or a tacno…