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The principle of differential monotonicity for cooperative games states that the differential of two players' payoffs weakly increases whenever the differential of these players' marginal contributions to coalitions containing neither of them weakly increases. Together with the standard efficiency property and a relaxation of the null player property, differential monotonicity characterizes the egalitarian Shapley values, i.e., the coex mixtures of the Shapley value and the equal division value for games with more than two players. For games that contain more than three players, we show that, cum grano salis, this characterization can be improved by using a substantially weaker property than differential monotonicity. Weak differential monotonicity refers to two players in situations where one player's change of marginal contributions to coalitions containing neither of them is weakly greater than the other player's change of these marginal contributions. If, in such situations, the latter player's payoff weakly/strictly increases, then the former player's payoff also weakly/strictly increases.

The principle of differential marginality for cooperative games states that the differential of two players' payoffs does not change when the differential of these players' marginal contributions to coalitions containing neither of them does not change. Together with two standard properties, efficiency and the null player property, differential marginality characterizes the Shapley value. For games that contain more than two players, we show that this characterization can be improved by using a substantially weaker property than differential marginality. Weak differential marginality requires two players' payoffs to change in the same direction when these players' marginal contributions to coalitions containing neither of them change by the same amount.

We suggest a weak version of differential monotonicity for redistribution rules: whenever the differential of two persons' income weakly increases, then their post-redistribution rewards essentially change in the same direction. Together with efficiency, non-negativity, and the average property, weak differential monotonicity characterizes redistribution via taxation at a fixed rate and equal distribution of the total tax revenue, i.e., a flat tax and a basic income.

The principle of differential marginality for cooperative games states that the differential of two players‘ payoffs does not change when the differential of these players‘ productivities does not change. Together with two standard properties, efficiency and the null player property, differential marginality characterizes the Shapley value. For games that contain more than two players, we show that this characterization can be improved by using a substantially weaker property than differential marginality. Weak differential marginality requires two players‘ payoffs to change in the same direction when these players‘ productivities change by the same amount.

We suggest a weak version of differential monotonicity for redistribution rules: whenever the differential of two persons’ income weakly increases, then their post-redistribution rewards essentially change in the same direction. Together with efficiency, non-negativity, and the null society property, weak differential monotonicity essentially characterizes redistribution via taxation at a
fixed rate and equal distribution of the total tax revenue, i.e., a flat tax and a basic income.