www.biomathforum.org/biomath/index.php/biomath ORIGINAL ARTICLE Inverse problem of the Holling-Tanner model and its solution Adejimi Adesola Adeniji, Igor Fedotov, Michael Y. Shatalov Department of Mathematics and Statistics, Tshwane University of Technology adejimi.adeniji@gmail.com, fedoptovi@tut.ac.za, shatalovm@tut.ac.za Received: 8 August 2018, accepted: 5 December 2018, published: 19 December 2018 Abstract—In this paper we undertake to consider the inverse problem of parameter identification of nonlinear system of ordinary differential equations for a specific case of complete information about solution of the Holling-Tanner model for finite number of points for the finite time interval. In this model the equations are nonlinearly dependent on the unknown parameters. By means of the proposed transformation the obtained equations become lin- early dependent on new parameters functionally dependent on the original ones. This simplification is achieved by the fact that the new set of pa- rameters becomes dependent and the corresponding constraint between the parameters is nonlinear. If the conventional approach based on introduction of the Lagrange multiplier is used this circumstance will result in a nonlinear system of equations. A novel algorithm of the problem solution is proposed in which only one nonlinear equation instead of the system of six nonlinear equations has to be solved. Differentiation and integration methods of the problem solution are implemented and it is shown that the integration method produces more accurate results and uses less number of points on the given time interval. Keywords-Parameter estimation, Goal function, Absolute error curves, Inverse method, Holling- Tanner model, Least square method, Differentiation method, Integration method I. INTRODUCTION The numerical evaluation of known coefficient of a dynamical system i.e. the problem of dy- namical system identification, is one of the most important problem of the mathematical biology [1], ecology [2], [3], [4], etc. Usually, to identify a dynamics of a system, it is necessary to have certain statistical information for time values about the unknown functions of this system. In the present paper we consider the inverse problem of parameter identification of the Holling-Tanner predator-prey model [5], [6]. This model is widely used in mathematical biology, for example, in the study of transmissible disease [7]. Several investi- gations have been done by various researchers on the mite-spider-mite, lynx-hare and sparrow-hawk- sparrow competition [8], [9], [10]. In [11], the authors proposed a method consisting in the direct integration of a given dynamical system with the subsequent application of quadrature rules and the least square method [12], [13] provided that there Copyright: c© 2018 Adeniji et al. This article is distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Citation: Adejimi Adesola Adeniji, Igor Fedotov, Michael Y. Shatalov, Inverse problem of the Holling-Tanner model and its solution, Biomath 7 (2018), 1812057, http://dx.doi.org/10.11145/j.biomath.2018.12.057 Page 1 of 9 http://www.biomathforum.org/biomath/index.php/biomath https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.11145/j.biomath.2018.12.057 A.A. Adeniji, I. Fedotov, M.Y. Shatalov, Inverse problem of the Holling-Tanner model and its solution is complete statistical information about the un- known function. In this paper, we assume that the complete information about the competing species is available and the two methods of solution, dif- ferentiation and integration methods, are proposed. The problem of the Holling-Tanner model iden- tification has its specifics, because it nonlinearly depends on the unknown parameters. It is possible to transform this model to a new form where the equations of the system linearly depends on the set of new parameters. These new parameters are not independent and we need to consider the constraint between the parameters, which are nonlinear. The Holling-Tanner model has only one constraint and hence, can be simply treated by a novel method developed by the authors. The theoretical consid- erations are accompanied by numerical examples where the developed algorithm is tested for both differentiation and integration methods of solution. It is shown that the integration methods is more accurate than the differentiation one and needs less amount of experimental information. II. MAIN RESULTS In our paper we consider the Holling-Tanner model [9], [14] described by the following system of equations:   ẋ = b1x− b2x2 − b3 x·yb4+x, ẏ = b5y − b6 y 2 x , t = 0, x(0) = x0, y(0) = y0 (1) where x = x(t), y = y(t), ẋ = dx(t) dt , ẏ = dy(t) dt , t is time and b1, · · ·b6 are positive constant pa- rameters [15]. Initial conditions for this system are formulated so that at t = 0 : x(t = 0) = x0 > 0 and y(t = 0) = y0 > 0. The main results relating to solution of this initial value problem were obtained in [10], [16], [17], [18] as • Solution of the initial value problem (1) {x(t),y(t)} with positive initial conditions is positive, i.e. x(t) > 0 and y(t) > 0 for t ≥ 0. • Initial value problem (1) has the positive steady-state solution [15] (x̃, ỹ) which cor- responds to either stable focus or stable node critical point depending on b1, · · ·b6 so that: x̃= b1b6−b3b5−b2b4b6 + √ ∆ 2b2b6 > 0, (2) ỹ = b5(b1b6−b3b5−b2b4b6 + √ ∆) 2b2b 2 6 > 0. where ∆ = (b1b6−b3b5− b2b4b6)2 +4b1b2b4b26. • Initial value problem (1) has unstable steady- state solution (˜̃x, ˜̃y) = ( b1 b2 , 0), which corresponds to the saddle critical point. III. ON SOLVABILITY OF IDENTIFICATION PROBLEM Assume that solution of initial problem (1), x(t) and y(t) is given on the finite time interval t ∈ [0,T] with initial t = 0 and terminal t = T time instants in N + 1 equispaced time instants ti = T N i ∈ [0,T]: xi = x(ti), yi = y(ti) (i = 0, · · · ,N) (3) Lets us formulate the identification problem for parameters b1, · · ·b6 from the known solution (3) This problem can be solved if the conditions of the following theorem are satisfied: Theorem 1. Parameters b1,b2,b3,b4 of model (1) can be identified by the least squares method if (N + 1) × 1-vector columns [xi] , [ x2i ] , [ x3i ] , [ẋi] , [xi,yi] are linearly independent. Parameters b5 and b6 of the above mentioned model can be identified by the mentioned method if (N + 1) × 1-vector columns [yi] and [ y2i x1 ] are linearly independent. Proof: By multiplying the first equation of system (1) by (b4 + x) and grouping the resulting terms we obtain C1(−x3(t)) + C2(−x(t)y(t)) + C3(−ẋ(t)) +C4(x(t)) + C5(x 2(t)) + (−x(t)ẋ(t)) = 0, (4) Biomath 7 (2018), 1812057, http://dx.doi.org/10.11145/j.biomath.2018.12.057 Page 2 of 9 http://dx.doi.org/10.11145/j.biomath.2018.12.057 A.A. Adeniji, I. Fedotov, M.Y. Shatalov, Inverse problem of the Holling-Tanner model and its solution where C1 = b2, C2 = b3, C3 = b4, C4 = b1b4, C5 = b1−b2b4 are new unknown parameters. It is easy to check that the parameters C1,C3,C4,C5 satisfy the following constrains: C1C23 + C3C5 − C4. Considering x(t) and y(t) in time instants t = ti we obtain the following overdetermined system of N + 1 linear algebraic equations: C1 ~f1 +C2 ~f2 +C3 ~f3 +C4 ~f4 +C5 ~f5−~f6 = 0, (5) where ~f1 = [f1i] = [ −x3i ] , ~f2 = [f2i] = [−xiyi] , ~f3 = [f3i] = [−ẋi] , ~f4 = [f4i] = [xi] , ~f5 = [f5i] = [ x2i ] , and ~f6 = [f6i] = [xiẋi] are (N + 1) × 1-vector columns. Hence, the un- known parameters C1, C2, C3, C4 and C5 can be found by, for example, the least squares method [19] by means of the constrained minimization of function G1: G1 = G1(C1,C2,C3,C4,C5,λ) = = 1 2 (C1 ~f1+C2 ~f2+C3 ~f3+C4 ~f4+C5 ~f5−~f6)T (C1 ~f1+C2 ~f2+C3 ~f3+C4 ~f4+C5 ~f5−~f6) + λ(C1C 2 3 + C3C5 −C4) −→ min (6) This problem can be solved providing that vectors ~f1, · · · , ~f5 are linearly independent in (6). The last term contains the Lagrange multiplier λ and the constraint between coefficients C1, · · · ,C5. Moreover, the second equation of system (1) can be rewritten in time instants t = ti as the following overdetermined system of N + 1 linear algebraic equations: C6 ~f7 + C7 ~f8 − ~f9 = 0, (7) where ~f7 = [f7i] = [yi] , ~f8 = [f8i] = [ −y2i xi ] , ~f9 = [f9i] = [ẏi] ,C6 = b5,C7 = b6. That is why coefficients C6,C7 can be found by application of the least square method by means of minimization of function G2 G2 =G2(C6,C7) = 1 2 ( C6 ~f7 + C7 ~f8 + ~f9 )T (C6 ~f7 + C7 ~f8 + ~f9) −→ min (8) This problem can be solved providing that vectors ~f7 and ~f8 are linearly independent of (8). Remark 2. In vectors ~f3, ~f6 the component ẋi, and in vector ~f9 the components ẏi are calculated by means of numerical differentiation of xi,yi with respect to time t and that is why the proposed method is called the differential method of identi- fication. Corollary 3. Parameters b1,b2,b3,b4 of the model (1) can be identified by the least square method [19] if (N + 1) × 1-vector columns[∫ ti 0 x(τ)dτ ] , [∫ ti 0 x2(τ)dτ ] , [∫ ti 0 x3(τ)dτ ] , [xi −x0] , [∫ ti 0 x(τ)y(τ)dτ ] are linearly dependent. Parameters b5 and b6 of the abovementioned model can be identified by the abovementioned method if (N + 1)×1-vector columns [∫ ti 0 y(τ)dτ ] and [∫ ti 0 y2(τ) x(τ) dτ ] are linearly dependent. Proof: Integrating expression (4) with respect to time t ∈ [0,T] we obtain C1 ( − ∫ t 0 x3(τ)dτ ) + C2 ( − ∫ t 0 x(τ)y(τ)dτ ) + C3 (x0 −x(t)) + C4 (∫ t 0 x(τ)dτ ) + C5 (∫ t 0 x2(τ)dτ ) − ( 1 2 (x2(t) −x20) ) = 0. (9) Integrating second equation of system 5 with re- spect to time t ∈ [0,T] we have C6 (∫ t 0 y(τ)dτ ) + C7 ( − ∫ t 0 y2(τ) x(τ) dτ ) −C3 (y(t) −y0) = 0. (10) Biomath 7 (2018), 1812057, http://dx.doi.org/10.11145/j.biomath.2018.12.057 Page 3 of 9 http://dx.doi.org/10.11145/j.biomath.2018.12.057 A.A. Adeniji, I. Fedotov, M.Y. Shatalov, Inverse problem of the Holling-Tanner model and its solution Performing all integrations in (9) and (10) from 0 to tj ∈ [0,T] we obtain the following overdeter- mined systems of N + 1 linear algebraic equations C1 ~g1 + C2 ~g2 + C3 ~g3 + C4 ~g4 + C5 ~g5 − ~g6 = 0, C6 ~g7 + C7 ~g8 − ~g9 = 0, (11) where ~g1 = [ − ∫ ti 0 x3(τ)dτ ] , ~g2 = [ − ∫ ti 0 x(τ)y(τ)dτ ] , ~g3 = [x0 −xi] , ~g4 = [∫ ti 0 x(τ)dτ ] , ~g5 = [∫ ti 0 x2(τ)dτ ] , ~g6 = [ 1 2 (x2i −x 2 0) ] , ~g7 = [∫ ti 0 y(τ)dτ ] , ~g8 = [ − ∫ ti 0 y2(τ) x(τ) dτ ] , ~g9 = [yi −y0] are the (N + 1)×1-vector columns. Now applying the method used in Theorem 1 we prove the Corollary. Remark 4. In vector ~g1, ~g2, ~g4, ~g5, ~g7, ~g8 the inte- grals are calculated by means of numerical inte- gration of xi,yi and their combinations with re- spect to time t and that is why the proposed method is called the integration method of identification. Remark 5. Note that expressions (5), (7) and (11) are linear with respect to unknown constants C1, · · · ,C7. Direct use of the constraint minimiza- tion using the Lagrange multiplier with constraint: C1C 2 3 + C3C5 −C4 = 0 (12) produces nonlinear system of equations for de- termination of six unknowns C1,C2,C3,C4,C5,λ. Thus the search is performed in six-dimensional space of parameters and hence this method sub- stantially complexifies the solution procedure. De- termination of parameters and C6 and C7 needs solution of linear system of two algebraic equa- tions. In the next section we describe an original problem solution algorithm reducing the search space dimension to one and using only linear matrix manipulations in the process of solution, which substantially simplifies and accelerates the problem solution. IV. SOLUTION OF THE PARAMETER IDENTIFICATION PROBLEM There are four original independent parameters (b1,b2,b3,b4) in the first equation of (1). First four C- parameters (C1,C2,C3,C4) depend on b- parameters so that there is one-to-one correspon- dence between them. The parameter C5 depends on the first four C-parameter as follows: C5 = C4 C3 −C1C23. (13) Hence, it is possible to consider (C1,C2,C3,C4) as independent parameters and introduce new name for the dependent parameter C5 = −λ. The novel algorithm will be considered in detail for the differentiation method of solution, i.e. with ~f1,··· ,9 - vector columns(see expression (5) and (7). The integration method of solution uses the same algorithm in which ~f1,··· ,9 - vector columns are changed to ~g1,··· ,9 -ones (see (11)). Param- eter λ will be selected from the given interval λ ∈ [λmin,λmax] and substituted in goal function G3 which is composed as follows G3 = G3(C1,C2,C3,C4,λ) = 1 2 ( C1 ~f1+C2 ~f2+C3 ~f3+C4 ~f4−(λ~f5+ ~f6) )T ( C1 ~f1+C2 ~f2+C3 ~f3+C4 ~f4−(λ~f5+ ~f6) ) (14) and subjected to minimization. In expression (14), parameter λ is considered as constant at every minimization and minimization itself is performed with respect to parameters C1,C2,C3,C4. Solu- tion of this problem is given by the following formula C(λ) = [C1(λ), C2(λ), C3(λ), C4(λ)] T = ( (LT1 L1) −1LT1 ) R(λ), (15) where L1 = [ ~f1 ~f2 ~f3 ~f4 ]T , R(λ) = λ~f5 + ~f6. (16) In expression (15) it is possible to calculate 1 × (N +1)- vector row ( (LT1 L1) −1LT1 ) only once and Biomath 7 (2018), 1812057, http://dx.doi.org/10.11145/j.biomath.2018.12.057 Page 4 of 9 http://dx.doi.org/10.11145/j.biomath.2018.12.057 A.A. Adeniji, I. Fedotov, M.Y. Shatalov, Inverse problem of the Holling-Tanner model and its solution after that perform its multiplication by (N +1)×1- vector row R(λ), which is very fast operation. Components of vector C(λ) and C5 = −λ are substituted in the constraint (12) to obtain the following nonlinear scalar equation C1(λ)C 2 3 (λ) −λC3(λ) −C4(λ) = 0, (17) which is solved with respect to λ. All roots of Equation (17) are found (sometimes to find all the roots it is necessary to expand the interval λ ∈ [λmin,λmax] to the left or to the right or to both sides). After finding a particular root λ the corresponding b-parameters are calculated as follows: b1(λ) = C4(λ) C3(λ) , b2(λ) = C1(λ), b3(λ) = C2(λ), b4(λ) = C3(λ). (18) (See (4)). The estimations of b-parameters are obtained from the proper selection of root λ = λ̄: b̄1 = b1(λ̄), b̄2 = b2(λ̄), b̄3 = b3(λ̄), b̄4 = b4(λ̄) (19) (one of the criteria of the correct choice of λ̄ must be positiveness of all estimated b̄ parameters, see Numerical Examples). Parameters b5 and b6 are estimated by means of minimization of the goal function of Equation 8. Solution of this problem is given by the formulas:[ b̄5 b̄6 ] = (LT2 L2) −1LT2 ~f9 (20) where L2 = [ ~f7 ~f8 ] is (N + 1)×2- matrix, (See (7)). Expression (15)-(20) give solution to the identi- fication problem by means of the differentiation method. To find solution of the problem by the integral method it is necessary to consider vectors ~g1,··· ,9 (See expression 11) instead of ~f1,··· ,9. In the next section you will find more information about application of the differentiation and integration methods. V. NUMERICAL EXAMPLES Let us solve the initial problem of Equation 1 with the following parameters: b1 = 0.2 b2 = 0.01 b3 = 0.05 b4 = 1 b5 = 0.062 b6 = 0.0223 (21) and initial conditions: [x0 y0] T = [10 5] T . The stable critical point has coordinates (x̃, ỹ) ≈ (7.77064, 21.4066) (see Equation 2) and it is the stable focus (eigenvalues of the linearized system in the vicinity of the critical point are ν1,2 ≈ −0.0138 ± 0.0735i, where i2=−1). The unstable saddle has coordinates (˜̃x, ˜̃y)=(20,0). Numerical solution x = x(t) on the time interval t ∈ [0,T = 150] in N + 1 = 25 points is shown in Figure 1 and solution y = y(t) is shown in Figure 2. Performing solution by means of the differential Fig. 1. Graph of solution x = x(t) Fig. 2. Graph of solution y = y(t) method in accordance with the described algorithm we obtain nonlinear Equation (12) from which the parameters are calculated: λ1 ≈ −0.3282, λ2 ≈ −0.1091 and λ3 ≈ 0.2087. As we see, only λ3 parameter can be selected from three Biomath 7 (2018), 1812057, http://dx.doi.org/10.11145/j.biomath.2018.12.057 Page 5 of 9 http://dx.doi.org/10.11145/j.biomath.2018.12.057 A.A. Adeniji, I. Fedotov, M.Y. Shatalov, Inverse problem of the Holling-Tanner model and its solution TABLE I VALUES OF b-PARAMETERS, CORRESPONDING TO DIFFERENT ROOTS OF EQUATION (12) FOR N + 1 = 25 (DIFFERENTIATION METHOD) Original Values λ1 ≈ −0.3282 λ2 ≈ −0.1091 λ3 ≈ 0.2087 b1 = 0.2000 −0.0580 −0.0621 0.2129 b2 = 0.0100 −0.0150 −0.0045 0.0108 b3 = 0.0500 −0.0295 −0.0026 0.0491 b4 = 1.0000 −18.0380 −10.5185 0.3906 roots, because λ1 and λ2 generate the negative values of b-parameters. The relative error of the b-parameters corresponding to λ3-parameter are as follows: ERROR%(b1) ≈ 6.437% ERROR%(b2) ≈ 7.725% ERROR%(b3) ≈ 1.832% ERROR%(b4) ≈ 60.943% (22) Estimation of parameters b5 and b6 gives coinci- dence with the original values of the parameters in four decimals with the following relative errors: ERROR%(b5) ≈ 0.029% ERROR%(b6) ≈ 0.028% (23) Comparison of original graphs with graphs ob- tained by numberical solution of initial problem (1) with the same initial conditions but with esti- mated parameters is shown in Figure 3 and Figure 4. As we see the estimated parameters gives quite good estimation of the process dynamics. The estimated values of the steady states are as follows (˜̃x, ˜̃y) ≈ (7.7143, 21.4282) with relative errors: ERROR%(x̃) ≈ 0.102% ERROR%(ỹ) ≈ 0.101% (24) Estimation of the parameters with N + 1 = 49 points gives λ1 ≈ −0.2585, λ2 ≈ −0.0878, λ3 ≈ 0.1914 and the following values of parameters (see Table 2) Fig. 3. Graph of original solution x = x(t) (dots) and solution with estimated parameters (solid line) Fig. 4. Graph of original solution y = y(t) (dots) and solution with estimated parameters (solid line) As we see, only λ3 parameter can be selected from the three roots, because λ1 and λ2 generate the negative values of b-parameters. One can see the substantial improvement of the parameters estimations. The relative errors of the b-parameters Biomath 7 (2018), 1812057, http://dx.doi.org/10.11145/j.biomath.2018.12.057 Page 6 of 9 http://dx.doi.org/10.11145/j.biomath.2018.12.057 A.A. Adeniji, I. Fedotov, M.Y. Shatalov, Inverse problem of the Holling-Tanner model and its solution TABLE II VALUES OF b-PARAMETERS, CORRESPONDING TO DIFFERENT ROOTS OF EQUATION (12) FOR N + 1 = 49 (DIFFERENTIATION METHOD) Original Values λ1 ≈ −0.2585 λ2 ≈ −0.0878 λ3 ≈ 0.1914 b1 = 0.2000 −0.0405 −0.0485 0.2010 b2 = 0.0100 −0.0119 −0.0036 0.0101 b3 = 0.0500 −0.0271 −0.0022 0.0500 b4 = 1.0000 −18.3099 −10.9975 0.9553 corresponding to λ3- parameter are as follows: ERROR%(b1) ≈ 0.496% ERROR%(b2) ≈ 0.583% ERROR%(b3) ≈ 0.087% ERROR%(b4) ≈ 4.469% (25) Estimation of parameters b5 and b6 gives coinci- dence with the original ones in four decimals with the following relative errors: ERROR%(b5) ≈ 0.002% ERROR%(b6) ≈ 0.002% (26) Comparison of original graphs with graphs ob- tained by numerical solution of initial problem (1) with the same initial conditions but with estimated parameters is shown in Figure 5 and Figure 6. Fig. 5. Graph of original solution x = x(t) (dots) and solution with estimated parameters (solid line) As we see the estimated parameters give very good estimation of the process dynamics. The Fig. 6. Graph of original solution y = y(t) (dots) and solution with estimated parameters (solid line) estimated values of the steady states are as follows (˜̃x, ˜̃y) ≈ (7.7077, 21.4102) with relative errors: ERROR%(x̃) ≈ 0.017% ERROR%(ỹ) ≈ 0.017% (27) Absolute errors in calculation of x = x(t) and y = y(t) in the differentiation method for N + 1 = 25 and N + 1 = 49 points are shown in Figure 7 and Figure 8. Performing solution by means of the integration method in accordance with the described algorithm we obtain three roots of nonlinear equation (12): λ1 ≈ −0.2391, λ2 ≈ −0.0725, λ3 ≈ 0.1899. As we see, only λ3 parameter can be selected from the three roots, because λ1 and λ2 generate the negative values of b-parameters. The relative errors of the b-parameters corresponding to λ3- Biomath 7 (2018), 1812057, http://dx.doi.org/10.11145/j.biomath.2018.12.057 Page 7 of 9 http://dx.doi.org/10.11145/j.biomath.2018.12.057 A.A. Adeniji, I. Fedotov, M.Y. Shatalov, Inverse problem of the Holling-Tanner model and its solution TABLE III VALUES OF b-PARAMETERS, CORRESPONDING DIFFERENT ROOTS OF EQUATION (12) FOR N + 1 = 25 (INTEGRATION METHOD) Original Values λ1 ≈ −0.2391 λ2 ≈ −0.0725 λ3 ≈ 0.1899 b1 = 0.2000 −0.0302 −0.0386 0.1999 b2 = 0.0100 −0.0115 −0.0032 0.0100 b3 = 0.0500 −0.0282 −0.0022 0.0500 b4 = 1.0000 −18.1074 −10.6869 0.9997 Fig. 7. Absolute Errors of Calculation for N +1 = 25 points (Differentiation method) Fig. 8. Absolute Errors of Calculation for N +1 = 49 points (Differentiation method) parameter are as follows: ERROR%(b1) ≈ 0.052% ERROR%(b2) ≈ 0.044% ERROR%(b3) ≈ 0.059% ERROR%(b4) ≈ 0.033% (28) Fig. 9. Absolute errors of calculation for N +1 = 25 points (Integration method) . Estimation of parameters b5 and b6 gives coinci- dence with the original values of b-parameter in four decimals with the following relative errors: ERROR%(b5) ≈ 0.008% ERROR%(b6) ≈ 0.007% (29) Comparison of original graphs with graphs ob- tained by numerical solution of initial problem (1) with the same initial conditions but with estimated parameters are visually indistinguishable from Fig- ure 5 and Figure 6. Absolute errors in calculation of x = x(t) and y = y(t) in the integration method for N + 1 = 25 points are shown in Figure 9. The parameters are estimated with very high accuracy at N + 1 = 25 points. The estimated values of the steady states are as follows (˜̃x, ˜̃y) ≈ (7.7062, 21.4061) with relative errors: ERROR%(x̃) ≈ 0.002% ERROR%(ỹ) ≈ 0.002% (30) Biomath 7 (2018), 1812057, http://dx.doi.org/10.11145/j.biomath.2018.12.057 Page 8 of 9 http://dx.doi.org/10.11145/j.biomath.2018.12.057 A.A. Adeniji, I. Fedotov, M.Y. Shatalov, Inverse problem of the Holling-Tanner model and its solution VI. CONCLUSION Two methods of solution of the inverse problem on parameter identification of the Holling-Tanner model with complete information are discussed. These are the differentiation and integration meth- ods of solution. The conditions are indicated at which all parameters of the model can be iden- tified. The main disadvantage of the conventional method of constraint minimization by means of the Lagrange multipliers is that the method gen- erates a system of six nonlinear equations with unknown initial guess values. Proposed is the novel method of the problem solution in which the six dimensional space of search is reduced to one dimensional space and the procedure of the initial guess value is performed by fast vector multiplication. Numerical examples of the pro- posed algorithm implementation are demonstrated for the differentiation and integration methods. It is shown that the integration method generates more accurate results than the differentiation one. The integration method also needs less number of points on the fixed time interval to produce accurate results than the differentiation method. VII. ACKNOWLEDGMENT The authors acknowledge the department of Mathematics and Statistics of the Tshwane Uni- versity of Technology towards the research. REFERENCES [1] M Yu Shatalov, AS Demidov, and IA Fedotov. Estimat- ing the parameters of chemical kinetics equations from the partial information about their solution. Theoretical Foundations of Chemical Engineering, 50(2):148–157, 2016. [2] Dmitrii Logofet. Matrices and Graphs Stability Prob- lems in Mathematical Ecology: 0. CRC press, 2018. [3] John Pastor. Mathematical ecology of populations and ecosystems. John Wiley & Sons, 2011. [4] Richard McGehee and Robert A Armstrong. Some mathematical problems concerning the ecological prin- ciple of competitive exclusion. 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