By: Neil E. Cotter	Probability
		Basic probability
		Partition
		creating a partition

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Tool: If we start with several mutually exclusive events, say A, B, and C, we may create a partition of sample space S by adding one more event, D, which we may describe as "other", meaning it contains all outcomes not in A, B, or C. For example, if we are talking about the parties people voted for in an election, we might say A = Democrat, B = Libertarian, C = Republican, and D = other. On a Venn diagram, D is the area around the outside of A, B, and C.