Abstract
Two integrable random vectors $\xi$ and $\xi^{*}$ in $\mathbb{R} ^{d}$ are said to be zonoid equivalent if, for each $u\in\mathbb{R} ^{d}$, the scalar products $\langle\xi,u\rangle$ and $\langle\xi^{*},u\rangle$ have the same first absolute moments. The paper analyses stochastic processes whose finite-dimensional distributions are zonoid equivalent with respect to time shift (zonoid stationarity) and permutation of its components (swap invariance). While the first concept is weaker than the stationarity, the second one is a weakening of the exchangeability property. It is shown that nonetheless the ergodic theorem holds for swap-invariant sequences and the limits are characterised.
Citation
Ilya Molchanov. Michael Schmutz. Kaspar Stucki. "Invariance properties of random vectors and stochastic processes based on the zonoid concept." Bernoulli 20 (3) 1210 - 1233, August 2014. https://doi.org/10.3150/13-BEJ519
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