LABORATORY 4
Dobrushin Mathematics Laboratory
Head of Laboratory – Dr.Sc. (Mathematics) Robert Minlos
Tel.: (095) 299-83-54; E-mail: minl@iitp.ru
The leading researchers of the laboratory include:
Dr.Sc. (Math.) |
L. Bassalygo |
Dr.Sc. (Math.) |
V. Prelov |
Dr.Sc. (Math.) |
M. Blank |
Dr.Sc. (Math.) |
S. Shlosman |
Dr.Sc. (Math.) |
V. Blinovsky |
Dr.Sc. (Math.) |
Yu. Suhov |
Dr.Sc. (Math.) |
A. Kirillov |
Dr.Sc. (Math.) |
M. Tsfasman |
Dr.Sc. (Math.) |
G. Margulis |
Dr. |
A. Rybko |
Dr.Sc. (Math.) |
N. Nadirashvili |
Dr. |
V. Shehtman |
Dr.Sc. (Math.) |
G. Olshanski |
Dr. |
S. Vladuts |
Directions of activity:
MAIN RESULTS
The uniqueness of Gibbs measure (in a bounded range of temperatures) in the space of trajectories induced by the Feynmann-Kac representation is proved for a quantum system of angarmonic oscillators on the lattice.
The limiting Hamiltonian describing elementary excitations of bound states for a weak-coupled system of lattice planar rotators is constructed. Also one-particle invariant subspaces of this Hamiltonian are found. The limiting Hamiltonian and its one-particle subspaces are found for the case of a lattice quantum system of 3-D rotators (a quantum Heisenberg model).
The spectral structure (point spectrum with the localization of eigenvectors) and its position have been found for a generator of stochastic dynamic of 1-D Ising model with random interaction.
A cluster expansion for a system of quantum oscillator with multidimensional spin space is constructed.
A central limit theorem is proved for a random walk of a particle in a random environment which is a Markov random field with short memory.
The uniqueness of a Gibbs measure on trajectories induced my Feynmann-Kac representation is proved for a weak-coupled system of lattice spin from a compact manifold.
Spectral properties of a 1-D stochastic Ising model with random bounded couplings are studied. It is proved that the integrated density of states for the generator of the corresponding dynamics near the upper spectrum edge has the form of the Lifshitz' tail. The asymptotic formula for the relaxation to equilibrium in average over the disorder for the system is obtained.
For a classical gas of particles in R^d interacting via a pair potential a region of parameters (inverse temperature and chemical potential) for that the set of Gibbs states is unique or it does not exist is investigated.
Ergodic properties of random maps from a compact set into itself are studied. Under some assumptions the quasi-compactness of a corresponding Perron-Frobenius operator is proved and its spectrum is analyzed. In this case it is shown that its spectrum constist of not more than a countable number of isolated eigenvalues of finite multiplicity.
It is proved that Markov processes semigroups describing finite closed networks converge to a limiting determinant dynamical system. The attractors of the limiting dynamical system for a class of closed networks is described.
Ergodic properties for open networks (with increasing to the infinity trajectory of corresponding hydrodynamical models) are investigated. A non-ergodicity of the original random process is proved under the assumption of the existence of a stable trajectory.
A Poisson hypothesis for general closed symmetric networks in the thermodynamical limit on finite time intervals is proved.
A stationary channel with a random parameter which is a completely singular stationary process independent of an input signal is considered. It is shown that under rather weak additional conditions, the information rate between the input signal
and output signal of such a channel coincides with the conditional information rate.
The capacity of non-binary constant-weight codes of weight one correcting a single localized error was find. For nonbinary codes it is proved that the Hamming bound
is asymptotically sharp in some range of the code rate.
The proofs of several theorems on codes are clarified using the Radon transformation for the suitable pair of dual homogeneous spaces. The new lattice invariant is introduced, namely, the formal power series which generalises the theta function and which is close to the McWilliams weight enumerator in coding theory.
For sequences of number fields with growing discriminant we prove generalizations of the Odlyzko – Serre bounds and of the Brauer – Siegel theorem, taking into account archimedean places.
The probability that the group of points of an elliptic curve over a fixed finite field is cyclic is investigated. An asymptotic formula for this probability (the cardinality of the field tending to infinity) is given. A description is given for the finite fields over which the group of all elliptic curves is cyclic.
It is shown that the minimum r-weight d_r of an anticode can be expressed in terms of the maximum r-weight of the corresponding code. As examples, we consider anticodes from homogeneous hypersurfaces (quadrics and Hermitian varieties). In a number of cases, all differences (except for one) of the weight hierarchy of such an anticode meet an analog of the generalized Griesmer bound.
It is proved that the weight function of a linear code, that is, an integer function defined on the vector space of messages, uniquely determines the code up to equivalence.
An axiomatisation of modal logic of connected topological spaces with universal and local modal operators is proposed. Completeness and the finite model property of this logic is proved. Studies of compactness property of modal and intermediate logics with respect to topological semantics are continued. It is proved that every modal logic with a single transitive modality is strongly complete (compact) in topological semantics if it is complete in relational semantics. We give counterexample to this claim in the bimodal case.
For three-paramereters family of stochastic point processes on 1-D lattice (arising in the representation theory) it is proved that correlation functions of these processes are given by a determinant formula with a kernel expressed in terms of Gauss hypergeometric function.
It is shown that a serie of known results about the relation of asymptotic combinatoric promblems and point ensemble, arising from random matrices, can be obtained as degenerations of a model, related to representations of an infinite simmetric group.
For an asymptotic of Plansherel measures on big Young diagrams it is shown that the local structure of typical random diagrams "inside" of the limit curve converges to a point random process with determinant correlation functions.
A new deduction of results about correlation functions for point processes with different families of partitions is proposed.
A version of Bike-Deift-Johanson hypothesis is proved. This hypothesis associate the asymptotic of the string length of Young random diagram with the asymptotic of maximum eigenvalues of random matrices.
CRANTS FROM:
Publications in 1999