“…, is called a solution to problem ( 9)-( 18) if the functions 𝑤𝑤𝑤𝑤 𝑟𝑟𝑟𝑟 * (𝑡𝑡𝑡𝑡), 𝑟𝑟𝑟𝑟 = 1,4 ���� , are continuously differentiable on [𝑡𝑡𝑡𝑡 𝑟𝑟𝑟𝑟−1 , 𝑡𝑡𝑡𝑡 𝑟𝑟𝑟𝑟 ) and satisfy equations ( 9), ( 11), ( 13), (15) with respective initial conditions and additional conditions ( 17), (18) with 𝜇𝜇𝜇𝜇 𝑗𝑗𝑗𝑗 = 𝜇𝜇𝜇𝜇 𝑗𝑗𝑗𝑗 * , 𝑗𝑗𝑗𝑗 = 1,4 ���� .…”