special functions arising from discrete painleve equations a survey this article is a survey on recent studies on special solutions of the discrete painleve equations especially on hypergeometric solutions of the q painleve equations the main part of this survey is based on the joint work k kajiwara t masuda m noumi y ohta y yamada hypergeometric solutions to the q painleve equations imrn 2004 47 2004 2497 2521 k kajiwara t masuda m noumi y ohta y yamada construction of hypergeometric solutions to the q painleve equations imrn 2005 24 2005 1439 1463 with kajiwara masuda ohta and yamada after recalling some basic facts concerning painleve equations for comparison we give an overview of the present status of studies on difference discrete painleve equations as a source of special functions

creating and relating three dimensional integrable maps we show how some integrable third order difference equations recently given in the literature are related to one another by the process of interchanging parameters and integrals using the same process we then create a 21 parameter family of integrable third order difference equations that contains the previous examples as special cases our methodology illustrates that the combination of finding 2 integrals i e integrals of the second iterate of the map exploiting linear parameter dependence and using the interchange process provides a powerful way to relate and create higher dimensional discrete integrable systems

time frequency localization operators a geometric phase space approach the author defines a set of operators which localize in both time and frequency these operators are similar to but different from the low pass time limiting operator the singular functions of which are the prolate spheroidal wave functions the author s construction differs from the usual approach in that she treats the time frequency plane as one geometric whole phase space rather than as two separate spaces for disk shaped or ellipse shaped domains in time frequency plane the associated localization operators are remarkably simple their eigenfunctions are hermite functions and the corresponding eigenvalues are given by simple explicit formulas involving the incomplete gamma functions

multiplicative equations related to the affine weyl group e8 we derive integrable equations starting from autonomous mappings with a general form inspired by the multiplicative systems associated with the affine weyl group e8 1 five such systems are obtained three of which turn out to be linearisable and the remaining two are integrable in terms of elliptic functions in the case of the linearisable mappings we derive non autonomous forms which contain a free function of the independent variable and we present the linearisation in each case the two remaining systems are deautonomised to new discrete painleve equations we show that these equations are in fact special forms of much richer systems associated with the affine weyl groups e7 1 and e8 1 respectively

degeneration through coalescence of the q painleve vi equation starting from the q discrete form of the painleve vi equation we obtain its degenerate forms by applying the procedure of coalescence of singularities the whole cascade of degenerate forms is thus obtained leading to new forms for the discrete painleve iv and v equations the lax pairs of these discrete painleve equations are explicitly constructed thus confirming their integrability

discretising systematically the painleve equations we apply a method that we have already proposed for the systematic discretisation of differential systems to the construction of discrete analogues of the painleve equations the important point is that in the case of the painleve equations one needs to preserve the integrability we show that this is indeed possible using our systematic procedure applied to the equations obtained from the hamiltonian description of the painleve equations

ultradiscrete painleve ii equation and a special function solution ultradiscretization with parity variables which keeps the information of original variables sign is applied to the q painleve ii equation of type a6 q pii a special solution of the resulting ultradiscrete system which corresponds to the special function solution of q pii is constructed ultradiscrete analogues of the q airy equation and its special solutions are also discussed in the process

painleve equations nonlinear special functions the six painleve equations pi pvi were first discovered about a hundred years ago by painleve and his colleagues in an investigation of nonlinear second order ordinary differential equations recently there has been considerable interest in the painleve equations primarily due to the fact that they arise as reductions of the soliton equations which are solvable by inverse scattering consequently the painleve equations can be regarded as completely integrable equations and possess solutions which can be expressed in terms of solutions of linear integral equations despite being nonlinear equations although first discovered from strictly mathematical considerations the painleve equations have arisen in a variety of important physical applications including statistical mechanics plasma physics nonlinear waves quantum gravity quantum field theory general relativity nonlinear optics and fibre optics the painleve equations may be thought of a nonlinear analogues of the classical special functions they possess hierarchies of rational solutions and one parameter families of solutions expressible in terms of the classical special functions for special values of the parameters further the painleve equations admit symmetries under affine weyl groups which are related to the associated backlund transformations in this paper i discuss some of the remarkable properties which the painleve equations possess including connection formulae backlund transformations associated discrete equations and hierarchies of exact solutions in particular the second painleve equation pii is used to illustrate these properties and some of the applications of pii are also discussed

universal character and q difference painleve equations the universal character is a polynomial attached to a pair of partitions and is a generalization of the schur polynomial in this paper we introduce an integrable system of q difference lattice equations satisfied by the universal character and call it the lattice q uc hierarchy we regard it as generalizing both q kp and q uc hierarchies suitable similarity and periodic reductions of the hierarchy yield the q difference painleve equations of types a 2g 1 a 1 1 g geq 1 d 5 1 and e 6 1 as its consequence a class of algebraic solutions of the q painleve equations is rapidly obtained by means of the universal character in particular we demonstrate explicitly the reduction procedure for the case of type e 6 1 via the framework of based on the geometry of certain rational surfaces

evolution equations for phase separation and ordering in binary alloys we explore two phenomenological approaches leading to systems of coupled cahn hilliard and cahn allen equations for describing the dynamics of systems which can undergo first order phase separation and order disorder transitions simultaneously starting from the same discrete lattice free energy function in the first approach a quasicontinuum limit is taken for this discrete energy and the evolution of the system is then assumed to be given by gradient flow in the second approach a discrete set of gradient flow evolution equations is derived for the lattice dynamics and a quasicontinuum limit is then taken we demonstrate in the context of bcc fe al binary alloys that it is important that variables be chosen that accommodate the variations in the average concentration as well as the underlying ordered structure of the possible coexistent phases only then will the two approaches lead to roughly the same continuum descriptions we conjecture that in general the number of variables necessary to describe the dynamics of such systems is equal ton 1 n 2 1 wheren 1 is given by the dimension of the span of the bases of the irreducible representations needed to describe the symmetry groups of the possible equilibrium phases andn 2 is the number of chemical components n 1 of these variables are nonconserved and the remaining are conserved and represent the average concentrations for the fe al alloys this implies a description of one conserved order parameter and one nonconserved order parameter the resultant description is given by a cahn hilliard equation coupled to a cahn allen equation via the lower order nonlinear terms the rough equivalence of the two phenomenological methods adds credibility to the validity of the resulting evolution equations a similar description should also be valid for alloy systems in which the structure of the competing phases is more complicated

10e9 solution to the elliptic painleve equation a function formalism for sakai s elliptic painleve equation is presented this establishes the equivalence between the two formulations by sakai and by ohta ramani grammaticos we also give a simple geometric description of the elliptic painleve equation as a non autonomous deformation of the addition formula on elliptic curves by using these formulations we construct a particular solution of the elliptic painleve equation expressed in terms of the elliptic hypergeometric function 10e9

integrable fourth order difference equations in this paper an attempt is made to find four dimensional analogs of two dimensional quispel roberts and thompson mappings and identified four distinct cases have been identified the obtained mappings are measure preserving the integrability of the isolated mappings is examined by constructing a sufficient number of integrals and their symplectic structure wherever possible

the surface induced spatial temporal structures in confined binary alloys abstract this paper examines surface induced ordering in confined binary alloys the hyperbolic initial boundary value problem ibvp is used to describe a scenario of spatiotemporal ordering in a disordered phase for concentration of one component of binary alloy and order parameter with non linear dynamic boundary conditions this hyperbolic model consists of two coupled second order differential equations for order parameter and concentration it also takes into account effects of the memory on the ordering of atoms and their densities in the alloy the boundary conditions characterize surface velocities of order parameter and concentration changing which is due to surface super cooling on walls confining the binary alloy it is shown that for large times there are three classes of dynamic non linear boundary conditions which lead to three different types of attractor s elements for the ibvp namely the elements of attractor are the limit periodic simple shock waves with fronts of discontinuities if is finite then the attractor contains spatiotemporal functions of relaxation type if is infinite and countable then we observe the functions of pre turbulent type if is infinite and uncountable then we obtain the functions of turbulent type

special solutions of discrete painleve equations through direct linearisation abstract we study the special solutions of discrete painleve equations which can be expressed through the discrete equivalent of quadratures the discrete painleve equations examined are the ones which appear in the classification based on affine weyl groups and which can be written as a system of two first order mappings the solutions obtained are the discrete equivalents of solutions which have been shown to exist for the continuous painleve equations

third order integrable difference equations generated by a pair of second order equations we show that the third order difference equations proposed by hirota kimura and yahagi are generated by a pair of second order difference equations in some cases the pair of the second order equations are equivalent to the quispel robert thomson qrt system but in the other cases they are irrelevant to the qrt system we also discuss an ultradiscretization of the equations

bilinear trilinear forms and exact solution of certain fourth order integrable difference equations a systematic investigation of finding bilinear or trilinear representations of fourth order autonomous ordinary difference equation x n 4 f x n x n 1 x n 2 x n 3 or xn 4 f xn xn 1 xn 2 xn 3 is made as an illustration we consider fourth order symplectic integrable difference equations reported by capel and sahadevan physica a 289 86 2001 and derived their bilinear or trilinear forms also it is shown that the obtained bilinear representations admit exact solution of rational form

an uncertainty principle for quaternion fourier transform we review the quaternionic fourier transform qft using the properties of the qft we establish an uncertainty principle for the right sided qft this uncertainty principle prescribes a lower bound on the product of the effective widths of quaternion valued signals in the spatial and frequency domains it is shown that only a gaussian quaternion signal minimizes the uncertainty

on the lattice geometry and birational group of the six point multi ratio equation the inherent self consistency properties of the six point multi ratio equation allow it to be considered on a domain associated with a t shaped coxeter dynkin diagram this extends the kadomtsev pe

the weyl correspondence and time frequency analysis describes the weyl correspondence and its properties showing how it gives a window independent definition of time frequency concentration for use in models in signal detection the definition of concentration is justified by showing that it gives reasonable answers in certain intuitive cases the weyl correspondence expresses a linear transformation as a weighted superposition of time frequency shifts of the signal and then authors explain why this is not the same as transforming a signal into the time frequency domain multiplying by a weight in the transform domain and taking the inverse the investigation into time frequency concentration and the weyl correspondence is justified by a new result the authors show that convolving the wigner distribution with a general smoothing function is equivalent to evaluating a weighted sum of spectrograms this is a new interpretation of the process of smoothing the wigner distribution to reduce cross terms it relates smoothing of the wigner distribution to the multiple window technique pioneered by thomson 1982

meromorphic solutions of difference equations integrability and the discrete painleve equations the painlev e property is closely connected to differential equations that are integrable via related iso monodromy problems many apparently integrable discrete analogues of the painlev e equations have appeared in the literature the existence of sufficiently many finite order meromorphic solutions appears to be a good analogue of the painlev e property for discrete equations in which the independent variable is taken to be complex a general introduction to nevanlinna theory is presented together with an overview of recent applications to meromorphic solutions of difference equations and the difference and q difference operators new results are presented concerning equations of the form w z 1 w z 1 r z w where r is rational in w with meromorphic coefficients

gravitational instantons with faster than quadratic curvature decay iii this is our third paper in a series on the gravitational instantons in this paper we classify alg and alh gravitational instantons in alg case we extend tian yau hein s construction slightly and show that it is the only alg gravitational instanton in alh case we prove a torelli type theorem

elliptic painleve equations from next nearest neighbor translations on the e_8 1 lattice the well known elliptic discrete painleve equation of sakai is constructed by a standard translation on the lattice given by nearest neighbor vectors in this paper we give a new elliptic discrete painleve equation obtained by translations along next nearest neighbor vectors this equation is a generic 8 parameter version of a 2 parameter elliptic difference equation found by reduction from adler s partial difference equation the so called q4 equation we also provide a projective reduction of the well known equation of sakai

a geometrical description of the discrete painleve vi and v equations we present a geometrical approach for the discrete painleve equations based on weyl groups the method relies on the bilinear formalism and assumes that the multidimensional function lives on the weight lattice of the appropriate affine weyl group the equations for the function a system of nonautonomous hirota miwa equations govern the evolution along the independent variable and the parameters of the equation the latter evolution induced by the schlesinger transformations in the present paper we analyse the case of the e 1 7 group using the geometrical description we derive the nonlinear discrete equations we find that in the case of the e 1 7 group these are the asymmetric q pvi and d pv that were recently proposed

singularity confinement and full deautonomisation a discrete integrability criterion abstract we present a new approach to singularity confinement which makes it an efficient and reliable discrete integrability detector our method is based on the full deautonomisation procedure which consists in analysing non autonomous extensions of a given discrete system obtained by adding terms that are initially absent but whose presence does not alter the singularity pattern a justification for this approach is given through an algebro geometric analysis we also introduce the notions of early and late confinement while the former is a confinement that may exist already for the autonomous system the latter corresponds to a singularity pattern longer than that of the autonomous case late confinement will be shown to play an important role in the singularity analysis of systems with non trivial gauge freedom for which the existence of an undetected gauge in conjunction with a sketchy analysis might lead to erroneous conclusions as to their integrability an algebro geometric analysis of the role of late confinement in this context is also offered this novel type of singularity confinement analysis will be shown to allow for the exact calculation of the algebraic entropy of a given mapping

tropical geometric interpretation of ultradiscrete singularity confinement using the interpretation of the ultradiscretization procedure as a non archimedean valuation we use results of tropical geometry to show how roots and poles manifest themselves in piece wise linear systems as points of non differentiability this will allow us to demonstrate a correspondence between singularity confinement for discrete integrable systems and ultradiscrete singularity confinement for ultradiscrete integrable systems

two variations on a3 a1 a1 1 type discrete painlev equations by considering the normalizers of reflection subgroups of types a 1 1 and a 1 3 in w d5 1 two subgroups w a3 a1 1 w a1 1 and w a1 a1 1 w a3 1 can be constructed from a a3a1a1 1 ty

integrable mappings and soliton equations ii abstract some simple solutions of discrete soliton equations are shown to satisfy 2d mappings we show that these belong to a recently introduced 18 parameter family of integrable reversible mappings of the plane thus lending weight to a previous conjecture we also give an example of an integrable mapping occuring in an exactly solvable model in statistical mechanics finally we discuss the notion of generalized reversibility

discretising the painleve equations a la hirota mickens we present a systematic method for discretising the painleve equations inspired by the method of hirota while extending it and by that of mickens by specifying it to the case at hand we derive various discrete analogues of painleve i and ii we obtain forms that have been previously derived as well as new ones in particular equations with a geometry described by the affine weyl group e8 1 as a by product we obtain also linearisable equations some of which are new

a classification of two dimensional integrable mappings and rational elliptic surfaces we classify two dimensional integrable mappings by investigating the actions on the fiber space of rational elliptic surfaces while the qrt mappings can be restricted on each fiber there exist several classes of integrable mappings which exchange fibers we also show an equivalent condition when a generalized halphen surface becomes a halphen surface of index m

direct method to construct integrals for nth order autonomous ordinary difference equations a direct method to construct integrals for an nth order autonomous ordinary difference equation oe wnnf wn wnn1 is presented as an illustration we first consider third order autonomous oe wn3

singularity analysis for difference painleve equations associated with the affine weyl group e 8 we propose a new expression for the generic additive discrete painleve equation associated with the affine weyl group this expression makes the singularity analysis of the mapping perfectly straightforward and allows the implementation of the singularity confinement criterion in an extremely simple way using this new approach we derive new classes of discrete painleve equations related to

connection matrices for ultradiscrete linear problems we present theory outlining associated linear problems for ultradiscrete equations the appropriate domain for these problems is the max plus semiring our main result is that despite the restrictive nature of the max plus semiring it is still possible to define a theory of connection matrices analogous to that of birkhoff and his school for systems of linear difference equations we use such theory to provide evidence for the integrability of an ultradiscrete difference equation

transformations of elliptic hypergeometric integrals we prove a pair of transformations relating elliptic hypergeometric integrals of different dimensions corresponding to the root systems bc n and a n as a special case we recover some integral identities conjectured by van diejen and spiridonov for bc n we also consider their type ii integral their proof of that integral together with our transformation gives rise to pairs of adjoint integral operators a different proof gives rise to pairs of adjoint difference operators these allow us to construct a family of biorthogonal abelian functions generalizing the koornwinder polynomials and satisfying the analogues of the macdonald conjectures finally we discuss some transformations of type ii style integrals in particular we find that adding two parameters to the type ii integral gives an integral invariant under an appropriate action of the weyl group e 7

born jordan quantization and the uncertainty principle the weyl correspondence and the related wigner formalism lie at the core of traditional quantum mechanics we discuss here an alternative quantization scheme the idea of which goes back to born and jordan and which has recently been revived in another context namely time frequency analysis we show in particular that the uncertainty principle does not enjoy full symplectic covariance properties in the born and jordan scheme as opposed to what happens in the weyl quantization

globally nilpotent differential operators and the square ising model we recall various multiple integrals with one parameter related to the isotropic square ising model and corresponding respectively to the n particle contributions of the magnetic susceptibility to the lattice form factors to the two point correlation functions and to their extensions the univariate analytic functions defined by these integrals are holonomic and even g functions they satisfy fuchsian linear differential equations with polynomial coefficients and have some arithmetic properties we recall the explicit forms found in previous work of these fuchsian equations as well as their russian doll and direct sum structures these differential operators are selected fuchsian linear differential operators and their remarkable properties have a deep geometrical origin they are all globally nilpotent or sometimes even have zero p curvature we also display miscellaneous examples of globally nilpotent operators emerging from enumerative combinatorics problems for which no integral representation is yet known focusing on the factorized parts of all these operators we find out that the global nilpotence of the factors resp p curvature nullity corresponds to a set of selected structures of algebraic geometry elliptic curves modular curves curves of genus five six and even a remarkable weight 1 modular form emerging in the three particle contribution 3 of the magnetic susceptibility of the square ising model noticeably this associated weight 1 modular form is also seen in the factors of the differential operator for another n fold integral of the ising class 3 h for the staircase polygons counting and in ap ry s study of 3 g functions naturally occur as solutions of globally nilpotent operators in the case where we do not have g functions but hamburger functions one irregular singularity at 0 or that correspond to the confluence of singularities in the scaling limit the p curvature is also found to verify new structures associated with simple deformations of the nilpotent property

some properties of the k dimensional lyness map this paper is devoted to study some properties of the k dimensional lyness map f x1 xk x2 xk a ki 2xi x1 our main result presents a rational vector field that gives a lie symmetry for f this vector field is used for k 5 to give information about the nature of the invariant sets under f when k is odd we also present a new as far as we know first integral for ff which allows us to deduce in a very simple way several properties of the dynamical system generated by f in particular for this case we prove that except on a given codimension one algebraic set none of the positive initial conditions can be a periodic point of odd period

studying discrete dynamical systems through differential equations abstract in this paper we consider dynamical systems generated by a diffeomorphism f defined on u an open subset of r n and give conditions over f which imply that their dynamics can be understood by studying the flow of an associated differential equation x x x also defined on u in particular the case where f has n 1 functionally independent first integrals is considered in this case x is constructed by imposing that it shares with f the same set of first integrals and that the functional equation f x det d f x x x u has some non zero solution several examples for n 2 3 are presented most of them coming from several well known difference equations

discrete dynamical systems associated with the configuration space of 8 points in ℙ3 ℂ a 3 dimensional analogue of sakai s theory concerning the relation between rational surfaces and discrete painleve equations is studied for a family of rational varieties obtained by blow ups at 8 points in general position in 3 we define its symmetry group using the inner product that is associated with the intersection numbers and show that the group is isomorphic to the weyl group of type e7 1 by parametrizing the configuration space by means of elliptic curves the action of the weyl group and the dynamical system associated with a translation are explicitly described as a result it is found that the action of the weyl group on 3 preserves a one parameter family of quadratic surfaces and that it can therefore be reduced to the action on 1 1

quantum discrete dubrovin equations the discrete equations of motion for the quantum mappings of kdv type are given in terms of the sklyanin variables which are also known as quantum separated variables both temporal discrete time evolutions and spatial along the lattice at a constant time level evolutions are considered in the classical limit the temporal equations reduce to the classical discrete dubrovin equations as given in a previous publication nijhoff f w 2000 chaos solitons fractals 11 19 28 the reconstruction of the original dynamical variables in terms of the sklyanin variables is also achieved

integrable mappings via rational elliptic surfaces we present a geometric description of the qrt map which is an integrable mapping introduced by quispel roberts and thompson in terms of the addition formula of a rational elliptic surface by this formulation we classify all the cases when the qrt map is periodic and show that its period is 2 3 4 5 or 6 a generalization of the qrt map which acts birationally on a pencil of k3 surfaces or calabi yau manifolds is also presented

isomonodromy transformations of linear systems of difference equations we introduce and study isomonodromy transformations of the matrix linear difference equation y z 1 a z y z with polynomial a z our main result is construction of an isomonodromy action of zm n 1 1 on the space of coefficients a z here m is the size of matrices and n is the degree of a z the birational action of certain rank n subgroups can be described by difference analogs of the classical schlesinger equations and we prove that for generic initial conditions these difference schlesinger equations have a unique solution we also show that both the classical schlesinger equations and the schlesinger transformations known in isomonodromy theory can be obtained as limits of our action in two different limit regimes similarly to the continuous case for m n 2 the difference schlesinger equations and their q analogs yield discrete painlev e equations examples include dpii dpiv dpv and q pvi

finite branch solutions to painleve vi around a fixed singular point every finite branch local solution to the sixth painleve equation around a fixed singular point is an algebraic branch solution in particular a global solution is an algebraic solution if and only if it is finitely many valued globally the proof of this result relies on algebraic geometry of painleve vi riemann hilbert correspondence geometry and dynamics on cubic surfaces resolutions of kleinian singularities and power geometry of algebraic differential equations in the course of the proof we are also able to classify all finite branch solutions up to backlund transformations

tomographic time frequency analysis and its application toward time varying filtering and adaptive kernel design for multicomponent linear fm signals since line integrals through the wigner spectrum can be calculated by dechirping calculation of the wigner spectrum may be viewed as a tomographic reconstruction problem in the paper the authors show that all time frequency transforms of cohen s class may be achieved by simple changes in backprojection reconstruction filtering the resolution cross term tradeoff that occurs in time frequency kernel selection is shown to be analogous to the resolution ringing tradeoff that occurs in computed tomography ct ideal reconstruction using a purely differentiating backprojection filter yields the wigner distribution whereas low pass differentiating filters produce cross term suppressing distributions such as the spectrogram or the born jordan distribution it is also demonstrated how this analogy can be exploited to tune the reconstruction filtering or time frequency kernel to improve the ringing resolution tradeoff some properties of the projection domain which is also known as the radon wigner transform are characterized including the response to signal delays or frequency shifts and projection masking or convolution last time varying filtering by shift varying convolution in the radon wigner domain is shown to yield superior results to its analogous cohen s class adaptive transform shift invariant convolution for the multicomponent linear fm signals that are investigated

an algebraic geometric approach to integrable maps of the plane we show that the dynamics of a birational map on an elliptic curve over a field is typically conjugate to addition by a point under the associated group law when the field is taken to be the function field of rational complex functions of one variable this amounts to an algebraic geometric version of the arnold liouville integrability theorem for planar integrable maps by products of this approach are that birational maps preserving foliations are necessarily the composition of two involutions and that relationships between birational maps preserving the same foliation can be described in terms of the respective points they add on the corresponding weierstrass curves when the result is applied to finite fields it helps explain some universal features of the periodic orbit distribution function for the reductions of integrable maps

new airy type solutions of the ultradiscrete painleve ii equation with parity variables the q difference painleve ii equation admits special solutions written in terms of determinants whose entries are the general solution of the q airy equation an ultradiscrete limit of the special solutions is studied using the procedure of ultradiscretization with parity variables then we obtain new airy type solutions of the ultradiscrete painleve ii equation with parity variables and the solutions have a richer structure than the known solutions

solution of the equivalence problem for the third painleve equation we find necessary conditions for a second order ordinary differential equation to be equivalent to the painleve iii equation under a general point transformation their sufficiency is established by reduction to known results for the equations of the form y f x y we consider separately the generic case and the case of reducibility to an autonomous equation the results are illustrated by the primary resonance equation

folding transformations of the painleve equations new symmetries of the painleve differential equations called folding transformations are determined these transformations are not birational but algebraic transformations of degree 2 3 or 4 these are associated with quotients of the spaces of initial conditions of each painleve equation we make the complete list of such transformations up to birational symmetries we also discuss correspondences of special solutions of painleve equations

holonomy of the ising model form factors we study the ising model two point diagonal correlation function c n n by presenting an exponential and form factor expansion in an integral representation which differs from the known expansion of wu mccoy tracy and barouch we extend this expansion weighting by powers of a variable the j particle contributions f j n n in the form factor expansion the corresponding extension of the two point diagonal correlation function c n n is shown for arbitrary to be a solution of the sigma form of the painleve vi equation introduced by jimbo and miwa in their isomonodromic approach to the ising model fuchsian linear differential equations for the form factors f j n n are obtained for j 9 and shown to have both a russian doll nesting and a decomposition of the corresponding linear differential operators as a direct sum of operators equivalent to symmetric powers of the second order linear differential operator associated with the elliptic integral e from this we show that each f j n n is unexpectedly simple being expressed polynomially in terms of the elliptic integrals e and k in contrast we exhibit some mathematical objects built from these form factors f j n n which break the direct sum of symmetric powers decomposition with its associated polynomial expressions first we show that the scaling limit of these differential operators and form factors breaks the direct sum structure but not the russian doll structure secondly we show that the previous extension of two point diagonal correlation functions c n n is for singled out values cos m n m n integers also solutions of fuchsian linear differential equations these solutions of painleve vi are not polynomial in e and k but are actually algebraic functions being associated with modular curves

matrix painleve systems we study a class of the isomonodromic deformation equations which we call matrix painleve systems they can be written in hamiltonian form the hamiltonian is written as the trace of the hamiltonian of the sixth painleve equation with canonical variables replaced by matrices we also derive the matrix version of the fifth fourth third and second painleve equation from the sixth matrix painleve system by the degeneration

super integrable four dimensional autonomous mappings a systematic investigation of the complete integrability of a fourth order autonomous difference equation of the type w n 4 w n f w n 1 w n 2 w n 3 is presented we identify seven distinct families of four dimensional mappings which are super integrable and have three independent integrals via a duality relation as introduced in a recent paper by quispel capel and roberts 2005 j phys a math gen 38 3965 80 it is observed that these seven families can be related to the four dimensional symplectic mappings with two integrals including all the four dimensional periodic reductions of the integrable double discrete modified korteweg devries and sine gordon equations treated in an earlier paper by two of us capel and sahadevan 2001 physica a 289 86 106

third order difference equations with two rational integrals a systematic investigation to derive three dimensional analogs of two dimensional quispel roberts and thompson qrt mappings is presented the question of integrability of the obtained three dimensional mappings with two independent integrals is also analyzed it is also shown that there exist three dimensional qrt maps with three n dependent integrals

some uncertainty principles for time frequency transforms of the cohen class the question of how the time frequency concentration of transforms of the cohen class is affected by fundamental properties is addressed the investigated transform properties are the marginal property the property of energy conservation and moyal s relation we show that each of these transform properties imply restrictions on the time frequency concentration of the cohen class and is thus related to an uncertainty principle different notions of time frequency concentration adapted to the property under consideration are applied

an area preserving action of the modular group on cubic surfaces and the painleve vi equation we construct an area preserving action of the modular group on a general 4 parameter family of affine cubic surfaces we present a geometrical background behind this construction that is a natural symplectic structure on a moduli space of rank two linear monodromy representations over the 2 dimensional sphere with four punctures and a natural symplectic action upon it of the braid group on three strings studying this action as a discrete dynamical system will be important in discussing the monodromy of the painleve vi equation

discrete painleve equations with maximal periodicities we present the discrete painleve equations the coefficients of which have the maximal periodicity allowed by the geometric description in terms of affine weyl groups for each equation of the degeneration pattern obtained by sakai and which starts at the group we give the corresponding discrete painleve equation some of these systems were already known but here we proceed in a systematic way filling in all the gaps in particular we derive the equations with maximal periodicity associated to the affine weyl group which is the richest system in the sakai classification and which has yet to be studied in detail

a coalescent diagram of the painleve equations from the viewpoint of isomonodromic deformations we revise garnier okamoto s coalescent diagram of isomonodromic deformations and give a possible coalescent diagram from the viewpoint of isomonodromic deformations we have ten types of isomonodromic deformations and two of them give the same type of painleve equation we can naturally put the 34th painleve equation in our diagram which corresponds to the flaschka newell form of the second painleve equation

affine weyl groups discrete dynamical systems and painleve equations a new class of representations of affine weyl groups on rational functions are constructed in order to formulate discrete dynamical systems associated with affine root systems as an application some examples of difference and differential systems of painleve type are discussed

how to find the conserved quantities of nonlinear discrete equations a method of finding conserved quantities of nonlinear ordinary difference equations is briefly discussed the method is based on the hypothesis that the conserved quantities are expressed by a ratio of two polynomials of dependent variables we obtain the conserved quantities of the discrete equation of motion of an anharmonic oscillator and a nonlinear difference equation of third order

the spatial temporal lamellar structures in the confined ideal polymer blends we consider the formation of self organized spatial temporal oscillating structures in symmetric binary polymer blends confined by two flat walls an influence of these walls on the formation of the oscillating volume structures is studied this phenomenon is simulated by an initial boundary value problem for the conserved order parameter or the concentration of one of the components in a binary mixture under a special choice the dynamical puri binder s boundary conditions these structures look like the lamellar structures the behavior of the order parameter is described by the modified cahn hilliard equation which models so called the non fickian diffusion in the symmetric binary polymer blends the nonlinear dynamical boundary conditions correspond to the process of adsorption desorption on the walls as a result these nonlinear surface processes induce into the volume the spatial temporal asymptotically periodic structures of relaxation pre turbulent or turbulent type with finite countable or non countable points of discontinuities on the period correspondingly the frequency of oscillations on the period follows a power law for the relaxation type and increases exponentially in the other cases

singularity confinement and chaos in discrete systems we present a number of second order maps which pass the singularity confinement test commonly used to identify integrable discrete systems but which nevertheless are non integrable as a more sensitive integrability test we propose the analysis of the complexity algebraic entropy of the map using the growth of the degree of its iterates integrability is associated with polynomial growth while the generic growth is exponential for chaotic systems

2 parameter tau τ function for the first painleve equation topological recursion and direct monodromy problem via exact wkb analysis we show that a 2 parameter family of tau functions for the first painleve equation can be constructed by the discrete fourier transform of the topological recursion partition function for a family of elliptic curves we also perform an exact wkb theoretic computation of the stokes multipliers of associated isomonodromy system assuming certain conjectures

geometric reductions of abs equations on an n cube to discrete painleve systems in this paper we show how to relate n dimensional cubes on which abs equations hold to the symmetry groups of discrete painlev equations we here focus on the reduction from the four dimensional cube to the q discrete third painlev equation which is a dynamical system on a rational surface of type with the extended affine weyl group we provide general theorems to show that this reduction also extends to other discrete painlev equations at least of type a

the self duality of discrete short time fourier transform and its applications the self duality of short time fourier transform stft is an elegant property and is useful in shedding light on the construction of stft and its resolution capability in this paper the discrete version of self duality is studied and the property is interpreted in the context of resolution capabilities of time frequency distributions in addition two applications are provided as showcases of these insights obtained from the interpretation in the first application the problem of stft synthesis is considered and self duality serves as an important indication of whether the synthesis problem at hands is properly formulated in the second application a new kind of high resolution time frequency distribution is constructed based on the understandings obtained by contrasting two of the most popular time frequency analysis tools namely the stft and the wigner distribution

monodromy preserving deformation of linear ordinary differential equations with rational coefficients iii abstract a unified treatment of monodromy and spectrum preserving deformations is presented in particular a general procedure is described to reduce the latter into the former consistently the concept of the function previously introduced for the former 2 is extended to the isospectral context it is shown that the general monodromy and spectrum preserving deformation equations can be written as hirota s bilinear differential equations by using the functions as dependent variables

bilinear equations and q discrete painleve equations satisfied by variables and coefficients in cluster algebras we construct cluster algebras the variables and coefficients of which satisfy the discrete mkdv equation the discrete toda equation and other integrable bilinear equations several of which lead to q discrete painleve equations these cluster algebras are obtained from quivers with an infinite number of vertices or with the mutation period property we will also show that a suitable transformation of quivers corresponds to a reduction of the difference equation

the q painleve v equation and its geometrical description we study the q painleve v equation which can be obtained from the degeneration of the q pvi in the form of the asymmetric q piii equation and present its geometrical description based on the bilinear formulation we obtain the equations for the multi dimensional functions of q pv in the form of nonautonomous hirota miwa systems which lives in the weight lattice of the a4 affine weyl group this geometrical approach furnishes in a straightforward way the miuras and the schlesingers of q pv

a geometric approach to singularity confinement and algebraic entropy a geometric approach to the equation found by hietarinta and viallet which satisfies the singularity confinement criterion but exhibits chaotic behaviour is presented it is shown that this equation can be lifted to an automorphism of a certain rational surface and can therefore be considered to be the action of an extended weyl group of indefinite type a method to calculate its algebraic entropy by using the theory of intersection numbers is presented

rational surfaces associated with affine root systems and geometry of the painleve equations we present a geometric approach to the theory of painleve equations based on rational surfaces our starting point is a compact smooth rational surface x which has a unique anti canonical divisor d of canonical type we classify all such surfaces x to each x there corresponds a root subsystem of e 1 8 inside the picard lattice of x we realize the action of the corresponding affine weyl group as the cremona action on a family of these surfaces we show that the translation part of the affine weyl group gives rise to discrete painleve equations and that the above action constitutes their group of symmetries by backlund transformations the six painleve differential equations appear as degenerate cases of this construction in the latter context x is okamoto s space of initial conditions and d is the pole divisor of the symplectic form defining the hamiltonian structure