Four-dimensional Algebras Research Articles

Sl(2,C)×D symmetry and conformal primary basis for massless fields

Alternative to the embedding formalism, we provide a group theoretic approach to the conformal primary basis for the massless field with arbitrary helicity. To this end, we first point out that sl(2,C) isometry gets enhanced to sl(2,C)×D symmetry for the solution space of the massless field with D the bulk dilatation. Then, associated with sl(2,C)×D symmetry, we introduce the novel quadratic Casimirs and relevant tensor/spinor fields to derive two explicit constraints on the bulk dilatation and sl(2,C) Casimirs. With this, we further argue that the candidate conformal primary basis can be constructed out of the infinite tower of the descendants of the left and right highest (lowest) conformal primary wave function of sl(2,C) Lie algebra, and the corresponding celestial conformal weights are determined by the bulk scaling dimension through solving out the exact on-shell conformal primary wave functions, where on top of the two kinds of familiar-looking on-shell conformal primary wave functions, we also obtain another set of independent on-shell conformal primary wave functions for the massless field with helicity |s|≥1. In passing, we also develop the relationship between the four-dimensional Lorentz Lie algebra and two-dimensional conformal Lie algebra from scratch, and present an explicit derivation for the two important properties associated with the conformal primary wave functions. Published by the American Physical Society 2024

Exact solutions, wave dynamics and conservation laws of a generalized geophysical Korteweg de Vries equation in ocean physics using Lie symmetry analysis

An evolution equation is a partial diferential equation that describes the time evolution of a physical system starting from given initial data. Evolution equations arise from many areas of applied and engineering sciences. To this end, this article investigates the analytical studies of a generalized geophysical Korteweg-de Vries equation in ocean physics. The examination of this model is conducted via the Lie group theory of diferential equations. In the first place, point symmetries, which are constituent elements of a four-dimensional Lie algebra, are systematically computed. Thereafter, one-parameter transformation groups for the algebra are calculated. Besides, going forward, a one-dimensional optimal system of subalgebras is derived in a procedural manner. Sequel to this, the subalgebras and combination of the achieved symmetries are invoked in the reduction proces which enables the derivation of nonlinear ordinary diferential equations associated with the generalized geophysical Korteweg-de Vries equation under study. Most of the achieved nonlinear ordinary diferential equations are further solved either via direct integration or using a power series approach. Furthermore, travelling wave solutions are initially obtained. This is attained via direct integration and the use of Jacobi elliptic function approach. These techniques enable the attainment of various exact soliton solutions, including non-topological soliton solutions as well as general periodic function solutions of note, such as cosine amplitude, sine amplitude, and delta amplitude solutions of the model. Furthermore, numerical simulations of the solutions are invoked to gain a gross knowledge of the physical phenomena represented by the under-study generalized geophysical Korteweg-de Vries equation in ocean physics. In the end, the investigation further gives attention to the calculation of conserved vectors for the model using Ibragimov's theorem for conservation laws, as well as Noether's theorem.

Malcev-like binary Lie algebras of dimension 5

We study anti-commutative algebras, which are extensions of a one-dimensional algebra by a four-dimensional nilpotent Lie algebra and at the same time extensions of the two-dimensional non-Abelian Lie algebra by an abelian algebra. These algebras, just like the five-dimensional solvable Malcev algebras, have a flag of subalgebras and can therefore be considered their closest relatives. We characterize binary Lie algebras in this class, called Malcev-like algebras, playing interesting role in non-associative Lie theory. We find normal forms of their multiplications, and determine their isomorphism classes.

Group Classification of the Unsteady Axisymmetric Boundary Layer Equation

Unsteady equations of flat and axisymmetric boundary layers are considered. For the unsteady axisymmetric boundary layer equation, the problem of group classification is solved. It is shown that the kernel of symmetry operators can be extended by no more than four-dimensional Lie algebra. The kernel of symmetry operators of the unsteady flat boundary layer equation is found and it is shown that it can be extended by no more than a five-dimensional Lie algebra. The non-existence of the unsteady analogue of the Stepanov–Mangler transformation is proved.

The Lie point symmetry criteria and formation of exact analytical solutions for Kairat-II equation: Paul-Painlevé approach

The renowned non-linear Kairat-II equation, which expresses the surface curves, is examined meticulously in this work. There has never been a study before that discussed conserved quantities, sensitivity analysis, Hamiltonian function, Lie symmetry invariance criteria, and invariant solutions of Kairat-II equation The Lie invariance criteria are taken into consideration by the symmetry generators. The suggested technique leads to in a four-dimensional Lie algebra, where the translation point symmetries in space and time correlate with the conservation of mass and the energy, respectively, and remaining point symmetries are dilation and scaling. Firstly, we use symmetry reduction of Lie subalgebras to obtain closed-form invariant solutions. In specific reduction cases, we transform the Kairat-II equation into a spectrum of non-linear ordinary differential equations, which have the benefit of being able to offer an extensive selection of closed-form solitary wave solutions. For this equation, the Cauchy problem cannot be solved by the inverse scattering transform, therefore, traveling wave exact solutions are generated using the analytical Paul-Painlevé approach. In both two and three dimensions, the graphical behavior of specific solutions is presented for specific quantities of physical factors of examined equation. Utilizing conservation laws multipliers, the study culminates by determining an extensive set of local conservation laws for the non-linear Kairat-II equation that are applicable to arbitrary constant coefficients. Instead of focusing on the physical aspects of conservation laws, this study computed the conserved quantities using a mathematical perspective that can be used to identify potential symmetries of partial differential equations, guiding readers toward the solutions of partial differential equations. The existence of the Hamiltonian function is presented. The model’s sensitivity to various starting conditions is highlighted by the sensitivity analysis.

Reduced Biquaternion Windowed Linear Canonical Transform: Properties and Applications

The quaternion windowed linear canonical transform is a tool for processing multidimensional data and enhancing the quality and efficiency of signal and image processing; however, it has disadvantages due to the noncommutativity of quaternion multiplication. In contrast, reduced biquaternions, as a special case of four-dimensional algebra, possess unique advantages in computation because they satisfy the multiplicative exchange rule. This paper proposes the reduced biquaternion windowed linear canonical transform (RBWLCT) by combining the reduced biquaternion signal and the windowed linear canonical transform that has computational efficiency thanks to the commutative property. Firstly, we introduce the concept of a RBWLCT, which can extract the time local features of an image and has the advantages of both time-frequency analysis and feature extraction; moreover, we also provide some fundamental properties. Secondly, we propose convolution and correlation operations for RBWLCT along with their corresponding generalized convolution, correlation, and product theorems. Thirdly, we present a fast algorithm for RBWLCT and analyze its computational complexity based on two dimensional Fourier transform (2D FTs). Finally, simulations and examples are provided to demonstrate that the proposed transform effectively captures the local RBWLCT-frequency components with enhanced degrees of freedom and exhibits significant concentrations.

Para-Kahler and Para-Hermitian Structures on Six-Dimensional Unsolvable Lie Algebras

In this paper, we investigate into the matter of the existence of para-Kahlerian and para-Hermitian structures on six-dimensional unsolvable Lie algebras that are semidirect products. According to the classification results, there are four Lie algebras that are semidirect products of the Lie algebras so(3), sl(2, R) and three soluble Lie algebras A3.1=R3, A3.3 and A3.5. We show that only g=A3.5⋉sl(2, R) has a symplectic structure, and it admits a para-Kahlerian structure of zero Ricci curvature. The paper presents calculated curvature characteristics and the method to find other para-Kahler structures based on deformations of some initial para-Kahler structure. Other Lie algebras admit para-Hermitian structures, i.e. integrable paracomplex structures consistent with the natural non-degenerate 2-form. It follows from the results of the paper that the sixdimensional symplectic Lie algebra must be solvable except for one case when g=A3.5⋉sl(2, R). It complements the well-known result of Chu Bon-Yao that a four-dimensional symplectic Lie algebra must be solvable.

Lie group analysis for obtaining the abundant group invariant solutions and dynamics of solitons for the Lonngren-wave equation

The Lonngren-wave equation (LW Equation), one of the many nonlinear evolution equations (N-EEs) that arise in the field of mathematical physics, is the subject of this study, which uses an extremely strong analytical technique known as “Lie group analysis” to create novel solutions. We obtain a five-dimensional optimal system based on four-dimensional Lie algebra. We compute the group invariant solutions via subalgebras. Our obtained solutions are based on the trigonometric, hyperbolic, and polynomial functions. By varying the parameters, the solutions exhibit wavelike properties that include bright, dark, singular, dark-singular-combined solitons, periodic singular and dark-bright-combined. The physical dynamics of the obtained solutions are explored by the 3D and 2D Mathematica simulations which are explaining the new properties of the model considered in this paper.

On 10-dimensional Exceptional Drinfeld algebras

Abstract Based on Mubarakzyanov’s classification of four-dimensional real Lie algebras, we classify ten-dimensional Exceptional Drinfeld algebras (EDAs). The classification is restricted to EDAs whose maximal isotropic (geometric) subalgebras cannot be represented as a product of a 3D Lie algebra and a 1D abelian factor. We collect the obtained algebras into families depending on the dualities found between them. Despite algebras related by a generalized Yang–Baxter deformation we find two algebras related by a different Nambu–Lie U-duality transformation. We show that this duality relates two Type IIA backgrounds.

Study on Poisson Algebra and Automorphism of a Special Class of Solvable Lie Algebras

We define a four-dimensional Lie algebra g in this paper and then prove that this Lie algebra is solvable but not nilpotent. Due to the fact that g is a Lie algebra, ∀x,y∈g,[x,y]=−[y,x], that is, the operation [,] has anti symmetry. Symmetry is a very important law, and antisymmetry is also a very important law. We studied the structure of Poisson algebras on g using the matrix method. We studied the necessary and sufficient conditions for the automorphism of this class of Lie algebras, and give the decomposition of its automorphism group by Aut(g)=G3G1G2G3G4G7G8G5, or Aut(g)=G3G1G2G3G4G7G8G5G6, or Aut(g)=G3G1G2G3G4G7G8G5G3, where Gi is a commutative subgroup of Aut(g). We give some subgroups of g’s automorphism group and systematically studied the properties of these subgroups.

Symmetry analysis and invariant solutions of Riabouchinsky Proudman Johnson equation using optimal system of Lie subalgebras

The Lie symmetry analysis of the Riabouchinsky Proudman Johnson (RPJ) equation is discussed in this research. In the onset, we derive the geometric vector fields using the classical Lie symmetry technique. Here, we have a four-dimensional Lie algebra. A five-dimensional optimal system is then obtained utilising this four-dimensional Lie algebra. After that, due to the similarity reduction, nonlinear ordinary differential equations (ODEs) are obtained. These nonlinear ODEs are very significant to reveal the dynamical profile of the solution regions of the RPJ equation. The obtained solutions have applications in fluid dynamics and are helpful for recent research because they are associated to Reynolds numbers. For the purpose of understanding the physical significance of the identified solutions, Mathematica simulations of those solutions are also provided.

Similarity transformations for modified shallow water equations with density dependence on the average temperature

Abstract The Lie symmetry analysis is applied for the study of a modified one-dimensional Saint–Venant system in which the density depends on the average temperature of the fluid. The geometry of the bottom we assume that is a plane, while the viscosity term is considered to be nonzero, as the gravitational force is included. The modified shallow water system is consisted by three hyperbolic first-order partial differential equations. The admitted Lie symmetries form a four-dimensional Lie algebra, the A 3,3 ⊕ A 1. However, for the viscosity free model, the admitted Lie symmetries are six and form the A 5,19 ⊕ A 1 Lie algebra. For each Lie algebra we determine the one-dimensional optimal system and we present all the possible independent reductions provided by the similarity transformations. New exact and analytic solutions are calculated for the modified Saint–Venant system.

А)нормальные экстремали левоинвариантных субфинслеровых квазиметрик на группе 𝐺2,1 × 𝐺2,1

In this paper, we find abnormal extremals of leftinvariant subFinsler quasimetrics on the direct Cartesian square of the connected twodimensional noncommutative Lie group, where the quasimetric is defined by a seminorm on the twodimensional or threedimensional generating subspace of the Lie algebra of this fourdimensional Lie group. A criterion for the nonstrict abnormality of these extremals is established. The solution to these problems is based on the previous general author's results on generating subspaces of fourdimensional Lie algebras and abnormal extremals of leftinvariant subFinsler quasimetrics on connected Lie groups with these Lie algebras. In conclusion, we consider the search problem for geodesics of a leftinvariant subRiemannian metric on the given Lie group, defined by the scalar product on the twodimensional generating subspace of its Lie algebra.

Lie Symmetry Analysis of the Aw–Rascle–Zhang Model for Traffic State Estimation

We extend our analysis on the Lie symmetries in fluid dynamics to the case of macroscopic traffic estimation models. In particular we study the Aw–Rascle–Zhang model for traffic estimation, which consists of two hyperbolic first-order partial differential equations. The Lie symmetries, the one-dimensional optimal system and the corresponding Lie invariants are determined. Specifically, we find that the admitted Lie symmetries form the four-dimensional Lie algebra A4,12. The resulting one-dimensional optimal system is consisted by seven one-dimensional Lie algebras. Finally, we apply the Lie symmetries in order to define similarity transformations and derive new analytic solutions for the traffic model. The qualitative behaviour of the solutions is discussed.

Classification of a family of 4-dimensional anti-commutative algebras and their automorphisms

We determine normal forms of the multiplication of four-dimensional anti-commutative algebras over a field K of characteristic zero having an analogous family of flags of subalgebras as the four-dimensional non-Lie binary Lie algebras, and hence can be considered as the closest relatives of binary Lie algebras. These algebras are extensions of K by the 3-dimensional nilpotent Lie algebra and at the same time extensions of a two-dimensional Lie algebra by a two-dimensional abelian algebra. We describe their groups of automorphisms as extensions of a subgroup of the group of automorphisms of the three-dimensional nilpotent Lie algebra by K.

Abnormal Extremals of Left-Invariant Sub-Finsler Quasimetrics on Four-Dimensional Lie Groups with Three-Dimensional Generating Distributions

We find the three-dimensional subspaces of four-dimensional Lie algebras which generate the algebras, as well as abnormal extremals on the connected Lie groups determined by these algebras and endowed with the left-invariant sub-Finsler quasimetrics defined by seminorms on the subspaces. Using the structure constants of Lie algebras and dual seminorms, we establish a criterion for the strict abnormality of the extremals.

Conjugacy classes of left ideals of Sweedler's four-dimensional algebra $ H_{4} $

<abstract><p>Let $ A $ be a finite-dimensional algebra with identity over the field $ \mathbb{F} $, $ U(A) $ be the group of units of $ A $ and $ L(A) $ be the set of left ideals of $ A $. It is well known that there is an equivalence relation $ \sim $ on $ L(A) $ by defining $ L_1\sim L_2\in L(A) $ if and only if there exists some $ u\in U(A) $ such that $ L_{1} = L_{2}u $. $ C(A) = \{[L]|L\in L(A)\} $ is the set of equivalence classes determined by the relation $ \sim $, which is a semigroup with respect to the natural operation $ [L_1][L_2] = [L_1L_2] $ for any $ L_1, L_2 \in L(A) $. The purpose of this paper is to describe the structures of semigroup of conjugacy classes of left ideals for the Sweedler's four-dimensional Hopf algebra $ H_{4} $.</p></abstract>

Групповой анализ уравнений равновесия нематохолестерика

We obtain a Lie algebra admitted by the system of equilibrium equations for a nematocholesteric, which models equilibrium configurations of the elastic field in the one-constant approximation of the continuum theory. In the case of a pure nematic, the system is found to admit a ten-dimensional Lie algebra, while in the case of a cholesteric, the system admits a four-dimensional Lie algebra. In addition, we have received particular analytical solutions of the system of model equations.

НОВАЯ КОНЦЕПЦИЯ РАЗРАБОТКИ ПОСТКВАНТОВЫХ АЛГОРИТМОВ ЦИФРОВОЙ ПОДПИСИ НА НЕКОММУТАТИВНЫХ АЛГЕБРАХ

Purpose of work is the development of a new approach to designing post-quantum digital signature algorithms that are free from the shortcomings of known analogs – large sizes of the signature and public key. Research method is the use of power vector equations with multiple occurrences of the signature S as a signature verification equation. The computational difficulty of solving equations of the said type relatively the unknown value of S ensures the resistance of the signature scheme to attacks using S as a fitting parameter. The possibility of calculating the value of S by the secret key is provided by using the public key in the form of a set of secret elements of the hidden group, masked by performing left and right multiplications by matched invertible vectors. Results of the study include a new proposed concept for the development of post-quantum digital signature algorithms on non-commutative algebras, which use a hidden commutative group. One of its main differences is the use of a secret key in the form of a set of vectors, the knowledge of which makes it possible to calculate the correct signature value for the random powers present in the verification equation. The form of the latter defines a system of quadratic vector equations connecting the public key with the secret, which is reduced to a system of many quadratic equations with many unknowns, given over a finite field. The computational difficulty of finding a solution to the latter system determines the security of the algorithms developed within the framework of the proposed concept. A quantum computer is ineffective for solving this problem, therefore, the said algorithms are post-quantum. As analogs in construction, digital signature algorithms based on the computational difficulty of the hidden discrete logarithm problem are considered, however, the use of a hidden group and exponentiation operations represent only a general technique for ensuring the correctness of the signature schemes developed within the framework of the concept, and not for specifying a basic computationally difficult problem. To improve the performance of the signature generation and verifications procedures, the four-dimensional algebras defined by sparse basis vector multiplication tables are used as an algebraic support. The proposed concept is confirmed by the development of a specific post-quantum algorithm that provides a significant reduction in the size of the public key and signature in comparison with the finalists of the NIST global competition in the nomination of post-quantum digital signature algorithms. Practical relevance: The developed new concept for constructing post-quantum digital signature algorithms expands the areas of their application in conditions of limited computing resources

Linear Bundle of Lie Algebras Applied to the Classification of Real Lie Algebras

We present a new look at the classification of real low-dimensional Lie algebras based on the notion of a linear bundle of Lie algebras. Belonging to a suitable family of Lie bundles entails the compatibility of the Lie–Poisson structures with the dual spaces of those algebras. This gives compatibility of bi-Hamiltonian structure on the space of upper triangular matrices and with a bundle at the algebra level. We will show that all three-dimensional Lie algebras belong to two of these families and four-dimensional Lie algebras can be divided in three of these families.