Let X be a finite set, let A1, A2,..., A be subsets of X, and let I be a subset of [n]. Let Y be the set of x = X such that x = A₁ for all i Є I but x A, for all iЄ [n] \ I. Show that Y = (-1)||AJ, ICJC|n] where the sum goes over all subsets J of [n] containing I, and AJ = njεJ Aj if JØ and AJ = X if J = 0. + Drag and drop your files or click to browse...