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Algebraic Geometry Commons

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Full-Text Articles in Algebraic Geometry

On Hilbert Modular Threefolds Of Discriminant 49, Lev A. Borisov, Paul E. Gunnells Nov 2012

On Hilbert Modular Threefolds Of Discriminant 49, Lev A. Borisov, Paul E. Gunnells

Paul Gunnells

Let K be the totally real cubic field of discriminant 49 , let \fancyscriptO be its ring of integers, and let p⊂\fancyscriptO be the prime over 7 . Let Γ(p)⊂Γ=SL2(\fancyscriptO) be the principal congruence subgroup of level p . This paper investigates the geometry of the Hilbert modular threefold attached to Γ(p) and some related varieties. In particular, we discover an octic in P3 with 84 isolated singular points of type A2 .


The Secant Conjecture In The Real Schubert Calculus, Luis D. García-Puente, Nickolas Hein, Christopher Hillar, Abraham Martín Del Campo, James Ruffo, Frank Sottile, Zach Teitler Nov 2012

The Secant Conjecture In The Real Schubert Calculus, Luis D. García-Puente, Nickolas Hein, Christopher Hillar, Abraham Martín Del Campo, James Ruffo, Frank Sottile, Zach Teitler

Zach Teitler

We formulate the Secant Conjecture, which is a generalization of the Shapiro Conjecture for Grassmannians. It asserts that an intersection of Schubert varieties in a Grassmannian is transverse with all points real if the flags defining the Schubert varieties are secant along disjoint intervals of a rational normal curve. We present theoretical evidence for this conjecture as well as computational evidence obtained in over one terahertz-year of computing, and we discuss some of the phenomena we observed in our data.


Road Trips In Geodesic Metric Spaces And Groups With Quadratic Isoperimetric Inequalities, Rachel Bishop-Ross, Jon Corson Dec 2011

Road Trips In Geodesic Metric Spaces And Groups With Quadratic Isoperimetric Inequalities, Rachel Bishop-Ross, Jon Corson

Rachel E. Bishop-Ross

We introduce a property of geodesic metric spaces, called the road trip property, that generalizes hyperbolic and convex metric spaces. This property is shown to be invariant under quasi-isometry. Thus, it leads to a geometric property of finitely generated groups, also called the road trip property. The main result is that groups with the road trip property are finitely presented and satisfy a quadratic isoperimetric inequality. Examples of groups with the road trip property include hyperbolic, semihyperbolic, automatic and CAT(0) groups. DOI: 10.1142/S0218196712500506