= Marginal-equivalent equilibria in additive contests
If contest rewards and costs add, a fixed deviation's expected payoff depends on each rival's per-contest <marginal distributions>, rather than on dependence between that rival's efforts across contests. Replacing the conditional independent sampling of two active efforts by another <copula> with the same conditional marginals therefore preserves every deviation payoff. Consequently it preserves the <Nash equilibrium>, even when the new joint strategy distribution is different. This explains why unique participation probabilities and bid marginals need not imply a unique full <mixed strategy>.
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