In this paper, Hirota's bilinear method is extended to a new KdV hierarchy with variable coefficients. As a result, one-soliton solution, two-soliton solution and three-soliton solutions are obtained, from which the uniform formula of N -soliton solution is derived. Thanks to the arbitrariness of the included functions, these obtained solutions possess rich local structural features like the ridge soliton and the concave column soliton. It is shown that the Hirota's bilinear method can be used for constructing multi-soliton solutions of some other hierarchies of nonlinear partial differential equations with variable coefficients.
Purpose
– The purpose of this paper is to analytically solve the (2+1)-dimensional nonlinear time fractional biological population model in the Caputo sense.
Design/methodology/approach
– The paper uses the variable separation method and the properties of Gamma function to construct exact solutions of the time fractional biological population model.
Findings
– New variable separation solutions are obtained, from which some known solutions are recovered as special cases.
Originality/value
– Solving fractional biological population model by the variable separation method and the properties of Gamma function is original. It is shown that the method presented in this paper can be also used for some other nonlinear fractional partial differential equations arising in sciences and engineering.
In this paper, the exp-function method is improved for constructing exact solutions of nonlinear differential-difference equations with variable coefficients. To illustrate the validity and advantages of the improved method, the mKdV lattice equation with an arbitrary function is considered. As a result, kink-type solutions are obtained which possess rich spatial structures. It is shown that the improved exp-function method can be applied to some other nonlinear differential-difference equations with variable coefficients.
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