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A combinatorial $t$-$(v,k,\lambda)$ design $D$ is a set of $k$-element subsets of $\{1,\ldots,v\}$ such that each $t$-element subset of $\{1,\ldots,v\}$ is contained in exactly $\lambda$ elements of $D$. Of particular interest are Steiner systems, which are designs with $\lambda = 1$.