If '''A''', '''B''' are 2 disjoint, closed subsets of a [[normal space]] '''X''', then there exist a [[continuous function]] '''f:X -> [0,1]''' such that '''f(A)''' = 0 and '''f(B)''' = 1.
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If '''A''', '''B''' are 2 disjoint, closed subsets of a [[normal space]] '''X''', then there exist a [[continuous function]] ''f'' : ''X'' → [0, 1], such that '''f(A)''' = 0 and '''f(B)''' = 1.