The development and application of GIS ultimately creates the demand for spatial information security, and access control is our primary concern. Spatial information is mostly stored and managed by database technologies, and SDE/RDBMS and ORDBMS are the most popular two. Correspondingly, there are two possible solutions for restricting access to spatial… (More)
We prove that the family of Q-Fano threefolds with Picard number one is birationally unbounded.
abstract Let Hol n x 0 (CP 1 , X) be the space of based holomorphic maps of degree n from CP 1 into a simply connected algebraic variety X. Under some condition we prove that the map Hol n x 0 (CP 1 , X) −→ Hol dn x 0 (CP 1 , X) obtained by compositing f ∈ Hol n x 0 (CP 1 , X) with g(z) = z d , z ∈ CP 1 induces rational homotopy equivalence up to some… (More)
We provide a natural smooth projective compactification of the space of algebraic maps from P 1 to P n by adding a divisor with simple normal crossings.