Probability · Venn diagrams & set notation
Chapter 1 · 4
The idea
Set notation
The formal language of sets — the universal set ξ, n(A) for a count, union A∪B ("in either, or both"), intersection A∩B, the complement A′, and combined expressions such as A∩B′ and (A∪B)′ — read as names for regions of a Venn diagram.
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Probability · Venn diagrams & set notation
Set notation
The formal language of sets — the universal set ξ, n(A) for a count, union A∪B ("in either, or both"), intersection A∩B, the complement A′, and combined expressions such as A∩B′ and (A∪B)′ — read as names for regions of a Venn diagram.
Why it works
Every symbol names a region
Set notation looks like a pile of unfamiliar symbols, but every symbol is a name for a region of a picture. Draw two overlapping circles inside a rectangle and you have already made four regions: in only, in both, in only, and in neither. The notation exists so you can say "that region" in writing, without pointing at it.The box: the universal set
Everything the question is about lives in the rectangle — the students in the class, the whole numbers from to , the people who answered the survey. The Greek letter ("xi") names that whole collection. It matters more than it looks, because below means "everything else", and "everything else" is meaningless until you have said what everything is.Keep reading — free
The rest of the explanation, plus 3 worked examples you step through move by move.
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