own creation [3].

Yx, Yy is the simultaneous income of one and the other player;

Yx1, Yy1, the specific amount of investment funds (current income) available to the players;

Yx´= x, Yy´= y is the future income of one and the other player (which are also the returns on the investment opportunities available to the players);

MYx´ = MYx´(Y), MYy´ = MYy´(Y) are the marginal return functions of the investment opportunities available to the players, and simultaneously the supply and demand curves of investment funds and investment opportunities