On the development and usage of the market economy parametrical regulation theory on the basis of one-class mathematical models Abdykappar A. Ashimov*, Nurlan A. Iskakov*, Yuriy V. Borovskiy**, Bahyt T. Sultanov*, Askar A. Ashimov* * Laboratory of Systems Analysis and Control, Institute of Problems of Informatics and Control 221 Bogenbay batyr str., Almaty, 050026, Republic of Kazakhstan ** Kazakh-British Technical University, 59 Tole be str., Almaty, 050000, Republic of Kazakhstan E-mail: * ashimov@ipic.kz, ** yuborovskiy@topmail.kz Abstract The paper offers further development and applications of the theory of a parametrical regulation of market economy evolution. This theory consists of the following sections: formation of a library of economic systems’ mathematical models; of rigidness (structural stability) of mathematical models; development of parametrical regulation laws etc. The work contains new results of the considered one class models’ rigidness research with and without parametrical regulation. 1. Introduction Many dynamic systems [8] including economic systems of nations [9, 10], after certain transformations can be presented by the systems of non-linear ordinary differential equations of the following type: dx f ( x, u , ), x(t0 ) x0 , dt (1) Here x ( x1 , x 2 ,..., x n ) X R n is a vector of a state of a system; u (u1 , u 2 ,...,u l ) W Rl - a vector of (regulating) parametrical influences; W, Х are compact sets with non-empty interiors - Int (W ) and Int ( X ) respectively; a vector of uncontrolled parameters ( , ,, ) R , is an opened connected set; maps f ( x, u, ) : X W R n 1 and f , x f , u f 2 m m are continuous in X W , [t 0 , t 0 T ] - a fixed interval (time). As is known [4], solution (evolution) of the considered system of the ordinary differential equations depends both on the initial values’ vector x0 Int ( X ) , and on the values of vectors of controlled (u) and uncontrolled ( ) parameters. This is why the result of evolution (development) of a nonlinear dynamic system under the given vector of initial values x0 is defined by the values of both controlled and uncontrolled parameters. Main components of market economy parametrical regulation theory have been developed and offered in [4, 5, 6] based on the fact of a possible description of a country’s economic system with the help of a mathematic model of type (1). Thus, in [3, 2] an approach is offered to finding the vector u values in the form of extremals of variation calculation task on the choice of parametrical regulation laws from the given set of parameters’ dependences on these or those significant endogenic indicators of economic system’s evolution. These laws are deduced from the conditions of economic processes optimal evolution, when certain parameters (e. g., price level) are preserved within the given scales. In [7] a dependence of the deduced optimal regulation laws on a non-regulated vector change has been investigated. An assumption has been proved on the existence of solutions to the above mentioned variation calculation tasks. A definition is provided and an assumption is proved on the sufficient terms of existence of extremals bifurcation points of the above-mentioned variation calculation tasks under the parametrical perturbations [4]. Development and usage of this theory in solving of certain tasks of parametrical regulation of market economy development depend on the choice of mathematic models meeting the requirements of economic system evolution. This requires additional study of roughness (structural stability) of the models chosen [1, 12]. The results of this research allow considering an adequate nature of mathematic models as well as a structural stability of the economic system described by this model. Development and application of a theory for the chosen models require that definite parametrical regulation laws should be chosen, and the dependence of the chosen laws on the values of the non-controlled parameter should be studied as well. The paper presents latest results of development and application of the parametrical regulation theory to a mathematical model of an economic system with the account of foreign commerce [3]. i s i i xi 1 1 i p i 1 i i Rid (11) 1 1 i 1 i f i 1 1 x i i ; (13) G i i pi M i f i ; (14) iL iI (1 n L i ) si Rid ; (15) 1 1 n pi 2.1. Model description n0 i (d iB d iP ) n p i O i dM i i M i ; dt pi bi (2) dQi M i fi i ; dt pi (3) dLGi dt rG i LGi (4) G i n p i i n L i s i RiL nO i (d iP dpi Q i i pi ; dt Mi R d R S dsi s i max 0, i S i , dt i Ri RiL LPi d iB ); (5) LGi ; k qi M i f i i (1 n pi ) G i (16) n L i (1 n L i )n p i s i RiL n pi ( ji i ij ) i L pi rG i LPi }; RiS P0Ai exp( p it ) i (1 CiL i iL pj pi 1 1 ii , j 3i ; ; ) P0 i ( pit ) (27) p2 O p2 С1 p1 p1 L 12 1 1O ;(18) L p2 O p2 1 C1 1 C1 p1 p1 p p С 2L 1 С 2O 1 p2 p 2 21 2L O2 ;(19) L 1 p1 O 1 p1 1 С2 1 C2 p2 p2 С1L 1 1I 1L 1O 1G 21 12 ; (20) (6) 1 2 2I 2L O2 G2 12 21 . (21) min{ Rid , RiS }; 1 i (12) O i 0 i pi M i f i ; { iI (10) M i xi ; 2. Research of rigidness (structural stability) of a mathematic model without parametrical regulation The considered task is solved on the basis of the parametrical regulation theory and on the sample of the following mathematical model [10], which presents the phase restrictions and restrictions in the permitted form of the researched variational calculus task at the choice of parametric regulations laws by the following relationships: ; i 1 i d iP i r2 i LGi ; i (7) d iB i r2 i LG i ; (9) (8) Here: i = 1, 2 is for a number of the state; t is for time; M i – total production capacity, Qi – the general stock of the goods in the market relatively some balance; LGi – total amount of a public debt; pi – price levels; si – average real wages; LPi -volume of manufacture debts; d iP and d iB - enterprise and bank dividends respectively; Rid and RiS – a supply and demand of a labor respectively; i , i - parameters of function f i( xi ) fi ; si pi xi – a solution to the equation ; iL and O i -consumer spending of workers and proprietors; iI - investment flows; G i consumption government spending; ij – consumer spending of the i-th country on an imported product from the j-th country; θ - exchange rate of the first country in relation to the exchange rate of the second country ( 1 , 2 1/ ); CiL (CiO ) - volume of imported product units consumed by the workers (proprietors) of the i-th country on the domestic product unit; i – norm of reservation; i - ratio of the average profit rate from commercial activities to the rate of return of the investor; r2i - deposits rate ; r1i - credit rate; rGi – government bonds rate; Oi factor of proprietors’ propensity to consume; i -share of consumption government spending from the gross domestic product; nPi , nOi , nLi - rates of the tax to flow payments, dividends tax and surtax accordingly; bi norm of a capital intensity of a production capacity unit; i -factor of power unit leaving which is caused by degradation; i - norm of amortization; ai - time constant; i - time constant setting the characteristic time-scale of wages process relaxation; P0i , P0Ai - initial values of amount of workers and total amount ablebodied population respectively; i - per capita consumption in group of employees; Pi 0 appointed tempo of demographic growth; k qi - share of the gross domestic products reserved in gold. This system reduces to a system of the eight ordinary differential equations for the variables, si are constant. The model parameters and initial conditions for the differential equations (2)-(6) were accepted on the basis of economic data of the Republic of Kazakhstan and the Russian Federation at 1996-2000 or (bi , r1i , r2i , rGi , nPi , nLi , i , si , Oi , i , i* , i ) are assessed through the solution of the parametric identification task ( i , i , i , i , bi , i , Qi (0)) . 2.2. Research of rigidness (structural stability) of a mathematic model Let us conduct statement of rigidness (structural stability) of a model under consideration in a closed field , basing on the definition of rigidness and the theorem on sufficient conditions of rigidness [12]. The conditions are as follows. Let N be some set and N be such a compact subset N that the closure of interior of N would be N. Let some vector field be given in the area of set N in N , then this field would determine the C 1 flow f in this area. The chain recurrent set of the flow f on the N is marked as R( f , N ) . Let the R( f , N ) be contained inside the N and have a hyperbolical structure; besides this, the f on the R( f , N ) would satisfy the transversality conditions on stable and unstable manifolds. Then the flow f on the N is weakly structurally stable. Particularly, if the R( f , N ) is an empty subset, then the flow f weakly structurally stable on the N. We will assume further that Rid > RiS . In this case differential equations (6) are replaced with the conditions of stability of variables si . Statement 1. Let N be a compact set in area (M 1 0, Q1 0, p1 0) or (M 1 0, Q1 0, p1 0) , of the phase area of differential equations system obtained from the (2-21), i.е. eight-dimension area of variables ( M i , Qi , pi , LG i ) , i 1, 2 ; closure of interior of N coincides with the N. Then the flow f determined by the (2-21) is weakly structurally stable on the N. F.i., a parallelepiped could be chosen as the N, with boundaries M i M i min , M i M i max , Qi Qi min , Qi Qi max , pi pi min , pi pi max , LG i LG i min , LG i LG i max Here 0 M i min M i max , 0 Qi min Qi max , Qi min Qi max 0 . or 0 pi min pi max , LG i min LG i max . The proof. To start with, let us make sure that the half-trajectory of the flow f beginning in any point of the set N under a certain value of t (t>0) comes out from the N. Let us consider any half-trajectory starting in the N. There are two cases possible for it if t 0 : all the half-trajectory points are left in the N, or for a certain t a point of the trajectory does not belong to the N. It follows in the first case from equation (5) of the system dp1 Q1 p1, that the variable p1(t) for all the dt M1 t 0 has got a derivative that is either more than some positive constant under the N (M 1 0, Q1 0, p1 0) or less some negative constant under the N (M 1 0, Q1 0, p1 0) , that is, the p(t) unlimitedly rises or tends to zero under the unlimited increase of the t. This is why, the first case is impossible, the orbit of any point from the N comes out from the N. As far as any chain recurrent set R( f , N ) is an invariant set of this flow, in case of its non-emptiness it should consist of whole orbits. Consequently, in our case the R( f , N ) is empty. The assumption has been proved. 3. Research of rigidness (structural stability) of the mathematic model with parametrical regulation Handling the law U i , under the fixed ki , in the system (2-21) means the substitution function U i , from (22) in equations of the system (2-21) instead of a parameter i , i or . The task of selection of an optimal parametrical regulation law for the economic system of the icountry at the level of one of the economic parameters ( i , i , ) was set in the following form: to find on the basis of mathematical model (2–21) an optimal parametrical regulation law in an environment of the set of algorithms (22), i.е. to find an optimal law (and its factor ki , ) out of the set { U i , }, which would have provided a maximum for the criteria Ki 3.1 The task of choice of effective parametrical regulation law The possibility of the choice of an optimal set of laws of type (3) of parametrical regulations was researched: at the level of one of the 3 parameters i ( 1) , i ( 2) , ( 3) ; at the time interval [t 0 , t 0 T ] and in an environment of the following algorithms. 1) U1i, k1i, 2) U 2i , M i (t ) consti ; M i (t0 ) k2i , 3) U 3i , k3i , M i (t ) consti ; M i (t0 ) pi (t ) consti ; pi (t0 ) 4) U 4i , k4i , 1 t0 T Yi (t )dt , T t0 (23) where Yi M i f i is a gross domestic product of the istate. The calculation experiments studied the impact of parametrical regulation of the first country (i=1). The closed set in the space of continuous vectorfunctions of discharge variables of the system (2-21) and regulating parametrical influences is defined with the following relationships: 1 p (t ) p1* (t ) 0.09 p1* (t ), ( M i (t ), Qi (t ), LGi (t ), p i (t ), s i (t )) X , (22) pi (t ) consti pi (t0 ) Here: U i , - is a α-law of regulation of βof the i-state, 1 4, 1 3 , Mi (t ) M , ,i (t ) Mi (t0 ), pi (t ) p , ,i (t ) pi (t0 ), t 0 – is parameter the time of the start of regulation, t t0 , t0 T , M , ,i (t ) , p , ,i (t ) are values of the production capacity and price levels of the i–state respectively under the U i , -regulation law. ki , is a tuned factor of the relevant law ( ki , 0 i ); consti is a constant that is equal to the assessment of the values of βparameter by the results of parametric identification. (24) 0 u a , 1, 4, 1, 3, t [t 0 , t 0 T ] Here a is the biggest possible value of a i (t ) are values of price levels under the parameter, p i U (t ) law of regulation; pi* (t ) are model (accounting) values of price levels in i-state without the parametrical regulation, X is a compact set of possible values of the given parameters. The formulated task for the first country is solved in two stages: - at the first stage optimal values of factors k1 , for each law U 1 , are defined by way of their values sorting in relevant intervals (quantized with small step), which provide maximum K 1 under the restrictions (24); - at the second stage an optimal parametrical regulation law of a parameter based on the first stage results for the maximum value of criterion K 1 will be chosen. is optimal for the other, both laws are optimal for the projection line itself. 3.2. Research of dependence of the optimum law of parametrical regulation on the values of uncontrolled parameters 3.3. Results of research of rigidness (structural stability) of a mathematical model with parametrical regulation. The given task of variational calculation considered its dependence on a two-dimensional factor (r2,1, ) of the mathematical model, whose Application of the found above optimal laws of parametrical regulation U 21, 2 and U 41, 2 means possible values belong to some area (rectangle) on the plane. As a result of calculation experiment dependence graphs of the optimal value of criterion K 1 on the values of parameters (r2,1 , ) were obtained for each of the 12 possible laws U 1 , , 1,4, 1,3 . Figure 1 demonstrates the given graphs for two laws, U 21, 2 and U 41, 2 , which give the biggest value of the criterion in area , an intersection line of corresponding surfaces and a projection of this intersection line upon the plane of values , which contains the bifurcation points of this two-dimensional parameter. This projection divides the rectangle into two parts; the regulating law Figure. 1. Graphs of dependences of the criterion’s K 1 optimal values on the parameters of interest rates on deposits r2,1 and currency exchange rate θ M 1 (t ) const12 M 1 (t 0 ) is optimal in one of these parts, and the law p (t ) U 41, 2 k 41,2 1 const12 p1 (t 0 ) U 21, 2 k 21, 2 (25) (26) replacement of parameter 1 by the relevant functions in the equation (14), the rest equations of the model remain unchanged. The proof of the weak structural stability of the mathematical model given in i. 2.2. and basing on equation (5), allows to find the following. Statement 2. Let N be a compact set in area (M 1 0, Q1 0, p1 0) or (M 1 0, Q1 0, p1 0) , of the phase area of the differential equations system obtained from the (2-21), i.e. eight-dimension area of variables ( M i , Qi , pi , LG i ) , i 1, 2 ; closure of interior of N coincides with the N. Then the flow f determined by the (2-21) and (25, 26) is weakly structurally stable on the N. 4. Conclusions This paper gives the following latest results of the development and usage of the parametrical regulation theory for a mathematical model of an economic system with the account of foreign commerce [10]: - the model’s weak structural stability for compact areas of its phase space has been proved; - the task of choice of optimal parametrical regulation laws has been solved for maximizing an average VAT of a country under some limitations upon price level increase; - a dependence of the found optimal laws on the values of non-controlled parameters has been defined and a set of optimal laws bifurcation points has been found; - a weak structural stability of a model preserved under the usage of the chosen parametrical regulation laws influenced by the non-controlled parameters of the model has been proved. 5. References [1] D.V. Anosov, “Rough systems”, Proceedings of the USSR Academy of Sciences’ Institute of Mathematics, 1985, Vol. 169, pp. 59-96 (in Russian). [2] A. Ashimov, Yu. Borovskiy, and As. Ashimov, “Parametrical Regulation Methods of the Market Economy Mechanisms”, Systems Science, 2005 Vol. 35, No. 1, pp. 89103. [3] А. Ashimov, Yu. Borovskiy, As. Ashimov, and O. Volobueva, “On the choice of the effective laws of parametrical regulation of market economy mechanisms”, Automatics and Telemechanics, 2005, No 3, pp. 105-112 (in Russian). [4] А. Ashimov, К. Sagadiyev, Yu. Borovskiy, N. Iskakov, and As. Ashimov, ’’Parametrical regulation of nonlinear dynamic systems development”, Proceedings of the 26th IASTED International Conference on Modelling, Identification and Control, Innsbruck, Austria, 2007, pp. 212-217. [5] А. Ashimov, К. Sagadiyev, Yu. Borovskiy, N. Iskakov, and As. Ashimov, (2007): “Elements of the market economy development parametrical regulation theory”, Proceedings of the Ninth IASTED International Conference on Control and Applications, Montreal, Quebec, Canada, 2007, pp. 296-301. [6] А. Ashimov, К. Sagadiyev, Yu. Borovskiy, N. Iskakov, and As. Ashimov, “On the market economy development parametrical regulation theory”, Proceedings of the 16th International Conference on Systems Science, Wroclaw, Poland, 2007, pp. 493-502. [7] А. Ashimov, К. Sagadiyev, Yu. Borovskiy, and As. Ashimov, “On Bifurcation of Extremals of one Class of Variational Calculus Tasks at the Choice of the Optimum Law of Parametrical Regulation of Dynamic Systems”, Proceedings of Eighteenth International Conf. On Systems Engineering, Coventry University, 2006, pp. 15-19. [8] Gukenheimer, J., P. Cholmes, Nonlinear fluctuations, dynamic systems and bifurcations of vector fields, Institute of Computer Researches, Moscow – Izhevsk, 2002 (in Russian). [9] V.М. Matrosov, М.М. Chrustalyov, О.V. Arnautov, and Krotov V.F., “On the highly aggregate model of development of Russia”, The Proceedings of the 2nd International conference “Analysis of instability development based on mathematical modeling”, Moscow, 1992, pp. 182-243 (in Russian). [10] Petrov, A., I. Pospelov, and A. Shananin, Experience of mathematical modeling of economy, Energoatomizdat, Moscow, 1996 (in Russian). [11] Pontryagin, A., The ordinary differential equations, Nauka, Moscow, 1970 (in Russian). [12] C. Robinson, “Structural Stability on Manifolds with Boundary”, Journal of differential equations, No. 37, 1980, pp. 1-11.