255 research outputs found
Singular del Pezzo fibrations and birational rigidity
A known conjecture of Grinenko in birational geometry asserts that a Mori
fibre space with the structure of del Pezzo fibration of low degree is
birationally rigid if and only if its anticanonical class is an interior point
in the cone of mobile divisors. The conjecture is proved to be true for smooth
models (with a generality assumption for degree 3). It is speculated that the
conjecture holds for, at least, Gorenstein models in degree 1 and 2. In this
article, I present a (Gorenstein) counterexample in degree 2 to this
conjecture.Comment: This is essentially a more detailed version of the second section of
arXiv:1310.5548. To appear in the proceedings of the conference 'Groups of
Automorphisms in Birational and Affine Geometry', held in Trento, Italy, 201
Probing the hydrogen melting line at high pressures by dynamic compression
We investigate the capabilities of dynamic compression by intense heavy ion beams to yield information about the high pressure phases of hydrogen. Employing ab initio simulations and experimental data, a new wide range equation of state for hydrogen is constructed. The results show that the melting line up to its maximum as well as the transition from molecular fluids to fully ionized plasmas can be tested with the beam parameters soon to be available. We demonstrate that x-ray scattering can distinguish between phases and dissociation states
Birational automorphisms of a three-dimensional double quadric with an elementary singularity
It is proved that the group of birational automorphisms of a
three-dimensional double quadric with a singular point arising from a double
point on the branch divisor is a semidirect product of the free group generated
by birational involutions of a special form and the group of regular
automorphisms. The proof is based on the method of `untwisting' maximal
singularities of linear systems.Comment: 18 page
Social policy of corporation and its efficiency
Π ΠΎΠ·ΠΊΡΠΈΠ²Π°ΡΡΡΡΡ Π·ΠΌΡΡΡ ΠΊΠΎΡΠΏΠΎΡΠ°ΡΠΈΠ²Π½ΠΎΡ ΡΠΎΡΡΠ°Π»ΡΠ½ΠΎΡ ΠΏΠΎΠ»ΡΡΠΈΠΊΠΈ ΡΡ ΠΏΡΠ΅Π΄ΠΌΠ΅Ρ ΡΠ° ΠΌΠ΅ΡΠΎΠ΄ΠΈ ΠΎΡΡΠ½ΠΊΠΈ Ρ ΡΠΎΡΠΌΠ°ΡΡ ΡΠΎΡΡΠ°Π»ΡΠ½ΠΈΡ
ΡΠ½Π²Π΅ΡΡΠΈΡΡΠΉ. ΠΡΠΎΠΏΠΎΠ½ΡΡΡΡΡΡ ΠΏΠΎΠΊΠ°Π·Π½ΠΈΠΊΠΈ Π΅ΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ Π·Π° ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠΈΠ²Π½ΡΡΡΡ,
Π΅ΠΊΠΎΠ½ΠΎΠΌΡΡΠ½ΡΡΡΡ ΡΠ° Π΄ΠΎΡΡΠ»ΡΠ½ΡΡΡΡ Π²ΠΈΡΡΡΠ΅Π½Π½Ρ ΡΠ΅Π°Π»ΡΠ½ΠΈΡ
ΡΠΎΡΡΠ°Π»ΡΠ½ΠΈΡ
ΠΏΡΠΎΠ±Π»Π΅ΠΌ.Opens the contents corporative social politicians its subject and methods of the estimation in format social investment. They are offered factors to efficiency for result, economy and practicability of the decision of the real social problems
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