Geometry of Continued Fractions — Sail statistics
v1.3 research notesFor every positive integer constant $C$ there exist only finitely many pairwise integer non-congruent faces with frequencies exceeding $C$....
Geometry of Continued Fractions — Sail statistics
v1.3 research notesIs that true that sum of all relative frequencies for all possible faces is finite for higher dimensions $(n\ge 3)$?...
Geometry of Continued Fractions — Sail statistics
v1.3 research notesIn case of positive answer to the above question find the generalization of the Gauss map and compare the corresponding frequencies of faces with the ...
Geometry of Continued Fractions — Further open questions
v1.3 research notesStudy geometric properties of Markov spectrum....
Some Open Problems in Elasticity — Testing convexity conditions
v1.3 research notesFind useful ways of verifying polyconvexity and quasiconvexity for stored-energy functions arising in anisotropic nonlinear elasticity....
Some Open Problems in Elasticity — Regularity of minimizers
v1.3 research notesDetermine when the minimizer $y^*$ in Theorem 2.1 of the source is smooth....
Some Open Problems in Elasticity — A positive Jacobian bound
v1.3 research notesProve or disprove that, under reasonable growth conditions on $W$, an energy-minimizing deformation satisfies $\det Dy^*(x)\ge\varepsilon>0$....
Some Open Problems in Elasticity — Nonglobal local minimizers
v1.3 research notesDevise general methods for proving the existence of local but nonglobal minimizers and other weak equilibria in nonlinear elastostatics....
Some Open Problems in Elasticity — Qualitative dynamics
v1.3 research notesDevelop a qualitative dynamics for dynamic theories of elasticity....
Some Open Problems in Elasticity — Atomistic foundations
v1.3 research notesEstablish the status of elasticity theory with respect to atomistic models....
Some Open Problems in Elasticity — Elastic-crystal free energies
v1.3 research notesFor free-energy functions $\psi(A,\theta)$ of elastic crystals, determine boundary conditions under which the minimum is attained and conditions under...
Open Problems in Integrable Systems — Topology of integrable systems, Lagrangian fibrations, and their invariants
v1.3 research notesUnder which additional assumptions does this principle become a rigorous theorem?...
Open Problems in Integrable Systems — Topology of integrable systems, Lagrangian fibrations, and their invariants
v1.3 research notesDescribe the symplectic invariants of stable rank-one singularities described by V. V. Kalashnikov. For such singularities, one of the action variable...
Open Problems in Integrable Systems — Topology of integrable systems, Lagrangian fibrations, and their invariants
v1.3 research notes[N. T. Zung] Study the topology and geometry of these singular fibers and their small neighbourhoods....
Open Problems in Integrable Systems — Topology of integrable systems, Lagrangian fibrations, and their invariants
v1.3 research notes[N. T. Zung] Give a clear description of these special singular fibers....
Open Problems in Integrable Systems — Two-dimensional case.
v1.3 research notesComplete the above table: {\rm (1)} construct new examples of natural Hamiltonian systems on closed two-dimensional surfaces admitting polynomial inte...
Open Problems in Integrable Systems — Polynomial in momenta integrals in higher dimensions.
v1.3 research notesConstruct stationary axially symmetric 4-dimensional Einstein metrics admitting Killing tensors of higher order....
Open Problems in Integrable Systems — Polynomial in momenta integrals in higher dimensions.
v1.3 research notes[Gilkey ] In the Riemannian case, is every $1$-homogeneous manifold locally homogeneous?...
Open Problems in Integrable Systems — Superintegrable systems
v1.3 research notes{\it Construct a natural Hamiltonian system on the 2-sphere with a nonconstant potential which is superintegrable by integrals of degree $\ge 3$ and a...
Open Problems in Integrable Systems — Around the Birkhoff conjecture
v1.3 research notesProve the algebraic version of Birkhoff conjecture for outer billiards in a non-Euclidean surface of constant curvature....
Open Problems in Integrable Systems — Around the Birkhoff conjecture
v1.3 research notesProve Conjecture [source label: Descon] it the case that the foliation admits (i) a rational, (ii) an algebraic first integral....
Open Problems in Integrable Systems — Around the Birkhoff conjecture
v1.3 research notesIs it possible to choose the domain so that the dynamics of the corresponding billiard map are locally (near the 2-periodic orbit) conjugated to the d...
Open Problems in Integrable Systems — Geometry of caustics, invariant surfaces, and commuting billiard maps
v1.3 research notesAre there plane billiards, other than ellipses, that possess rational caustics with two different values of the rotation numbers? Same question for ou...
Open Problems in Integrable Systems — Noncommutative integrable maps
v1.3 research notes{\rm (V. Retakh) Establish complete integrability of the noncommutative version of the leapfrog map. Define noncommutative versions of the pentagram m...
Open Problems in Integrable Systems — Bi-Poisson vector spaces
v1.3 research notesConsider the action of $ Aut (V,J)$ on $V$. Describe the partition of $V$ into $ Aut (V,J)$-orbits. More generally, describe the action of $ Aut (V,J)...
Open Problems in Integrable Systems — Bi-Poisson vector spaces
v1.3 research notesFind necessary and sufficient conditions for the bi-Lagrangian Grassmannian $LG(V,J)$ to be a smooth algebraic variety. Describe the partition of $LG(...
Open Problems in Integrable Systems — Bi-Poisson vector spaces
v1.3 research notesDo bi-integrable systems exist for each algebraic type?...
Open Problems in Integrable Systems — Argument shift method and Jordan-Kronecker invariants of Lie algebras
v1.3 research notesAre there any restrictions on the algebraic type of the pencils $\mathcal{A}_{x+\lambda a}$? Which algebraic types can be realised by means of an appr...
Open Problems in Integrable Systems — Argument shift method and Jordan-Kronecker invariants of Lie algebras
v1.3 research notesStudy examples of ``quadratic $+$ linear'' Poisson pencils. Compute their algebraic types and construct complete families of polynomials in bi-involut...
Open Problems in Integrable Systems — Argument shift method and Jordan-Kronecker invariants of Lie algebras
v1.3 research notesIs it true that for any quadratic Poisson bracket (defined on a vector space), there exists a polynomial integrable system?...
Open Problems in Integrable Systems — Nijenhuis operators: singular points and global properties
v1.3 research notesDescribe closed manifolds $M$ which admit Nijenhuis operators $L(x)$ that are algebraically regular at each point $x\in M$....
Open Problems in Integrable Systems — Nijenhuis operators: singular points and global properties
v1.3 research notesLet us fix a certain algebraic type of a linear operator, i.e., its Segre characteristic (see above). Does there exist a Nijenhuis operator $L$ in $\m...
Open Problems in Integrable Systems — Nijenhuis operators: singular points and global properties
v1.3 research notesDescribe all the functions $f(x,y)$ of two variables defined in a neighbourhood of $(0,0)\in\mathbb{R}^2$ such that ; $f_y(0,0)\not\equiv 0$; ; $f_y(0...
Open Problems in Integrable Systems — Nijenhuis operators: singular points and global properties
v1.3 research notesConsider a smooth map $\Phi=(\sigma_1,\dots,\sigma_n): U(0) \to \mathbb{R}^n$, where $U(0)$ is a neighbourhood of the origin $0\in \mathbb{R}^n$. We a...
Open Problems in Integrable Systems — Nijenhuis operators: singular points and global properties
v1.3 research notesDescribe/classify the collections of algebraically independent homogeneous polynomials $\sigma_1, \dots, \sigma_n$, $\deg \sigma_k = k$, in $n$ variab...
Open Problems in Integrable Systems — Nijenhuis operators: singular points and global properties
v1.3 research notesDescribe the structure of singularities of $\Phi=(\sigma_1,\dots,\sigma_n): M \to \mathbb{R}^n$ in terms of the singular points of the recursion opera...
Open Problems in Integrable Systems — Poisson geometry and action-angle variables
v1.3 research notesWhich foliations with affine leaves can be described as the image of the moment map?...
Open Problems in Integrable Systems — Poisson geometry and action-angle variables
v1.3 research notesConsider a Poisson manifold $M$ of even dimension such that it is symplectic on a dense set $U\subset M$. Assume that $M$ is endowed with a toric acti...
Open Problems in Integrable Systems — Integrability and Quantisation
v1.3 research notes[S. V\ u Ng{\d o}c] Given a set of semiclassical operators that verify conditions [source label: item:self-adjoint ] and [source label: item:commute] ...
Open Problems in Integrable Systems — Integrability and Quantisation
v1.3 research notes[S. V\ u Ng{\d o}c] Define (and detect) the quantum Chern class....
Open Problems in Integrable Systems — Integrability and Quantisation
v1.3 research notes[\'{A}. Pelayo] Can one make progress in counting the number of fixed points by studying the spectrum of the quantisation of $\mu \colon M \to S^1$?...
Open Problems in Integrable Systems — Quantum integrability for polynomial in momenta integrals
v1.3 research notesWhat are necessary and/or sufficient conditions on a metric $g$ such that every polynomial integral of its geodesic flow is quantisable?...
Open Problems in Integrable Systems — Integrable systems and geometric quantisation
v1.3 research notes[Miranda-Presas-Solha ] Modify this scheme to get finite dimensional representation spaces for focus-focus and hyperbolic singularities that still cap...
Problems Around Polynomials — Conjecture 2
v1.3 research notes[folklore, very irritating] For any set of charges of the same sign in $\mathbb{R}^n$, the set of its points of equilibrium is finite....
Problems Around Polynomials — Conjecture 3
v1.3 research notes[A. Gabrielov, D. Novikov, B. Sh., seems good, but no progress] Let $(x_1,y_1),(x_2,y_2),\dots, (x_N,y_N)$ be a collection of points in $\mathbb{R}^2$...
Problems Around Polynomials — Problem 1
v1.3 research notes[B. Sh., looks bad, but very important] Does there exist an upper bound for the number of real roots valid for all non-trivial solutions of all equati...
Problems Around Polynomials — Problem 2
v1.3 research notes[D. Khavinson, I. Itenberg, B. Sh., apparently bad] Find the maximal possible number $\#(2k, l)$ of isolated zeros for real non-negative polynomials o...
Problems Around Polynomials — Problem 3
v1.3 research notes[G. Ottaviani, B. Sh., seems good] Find the maximal possible number $\widetilde\#(2k, l)$ of isolated zeros for real non-negative polynomials of degre...
Problems Around Polynomials — Conjecture 4
v1.3 research notes[G. Ottaviani, B. Sh., seems good] For any number of variables, $\widetilde\#(2k,l)=k^l$....
Problems Around Polynomials — Problem 4
v1.3 research notes[S. Fisk, seems bad, see , p. 575] Given a pair of real polynomials $(p,q),$ give restrictions on the location of the roots of $p+iq$ in terms of the ...