Doob exposure martingale (source code)

= Doob exposure martingale
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{title2=$M_i=\mathbb E[f\mid Z_1,\ldots,Z_i]$}

= Doob martingale of independent coordinates
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{synonym}

Expose independent coordinates successively and take the conditional mean of a function after each exposure. These conditional means form a <martingale> from $\mathbb Ef$ to $f$. A coordinate oscillation bound $c_i$ gives a conditional interval of length $c_i$ for the corresponding increment, by coupling the unexposed coordinates. Applying the <Hoeffding lemma> to these conditional ranges proves the <McDiarmid inequality>.